# MES 40 - Troubleshoot cause of temp reading on display higher than actual temps



## hkeiner

I purchased a MES 40 (model 20070710) in October 2010 and am very happy with it. However, I have found that the temperature reading on the MES display consistently shows 20-30 degrees higher than the temperature shown on my Taylor 1470N digital thermometer. (I checked the accuracy of the Taylor using the boiling water method and found that it was within a few degrees of 212). To compensate for the MES display error, I set the temperature on the MES control unit 20-30 degrees higher than my desired temperature. This works OK for things I want to smoke at 225-250 (ribs, butts, etc) but it does limit me from smoking at higher actual temperatures (e.g., 275 degrees for chicken, etc.). I moved the Taylor probe around a bit inside the MES box and still found the disparity.

I am thinking that either one of the sensors inside the MES is at fault or the control unit on the top of the MES is at fault.   There are two sensers on the back panel of my MES 40. One is at the top left (sensor #1) and the other is in the middle right (sensor #2). I have read that the #1 sensor is called a "limit sensor" and the #2 is called a "temperature sensor". While I get the general idea as to what these sensor may do, I don't know how to test them or if they can be a likely culprit.

In short, these are  my questions:

- If one of these sensors can cause a display error, which one is it most likely to be?

- Can the sensors be bench tested using a multimeter, and if so, are there any specs (e.g., ohms/voltage at a specific termperature) for testing them?

- Is it more likely that the control unit is at fault, and if so can it be tested using a multimeter or any other way?

For cars, appliances and such I don't generally like to throw parts at a problem without first diagnosing a failed part. Perhaps it is not feasable to do this on the MES and that guessing is more practical. If so, I would appreciate your "guesses" before I order any sensors from Masterbuilt and remove the back panel to replace them (which would be a pain).

Thanks in advance for any responses.


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## southensmoker

Would also like to know....  Mine is off too


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## SmokinAl

Mine is off as well, but the other way. I set it at 215 if I want to cook at 225-230.


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## markk

I have the same Model # smoker as you. I have also noticed that the temperature displayed on the controller is lower than my Maverick thermometer when smoking a load of meat. I compared the two temperatures one day with the smoker empty and they seemed to match. Not sure what that means though


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## porked

Try placing your Maverick probe in different spots inside the MES, my guess is you'll get different readings, I know I did.


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## Bearcarver

My Maverick is nearly always higher than the MES digital, but they get closer after the smoker comes to the set temp, and simmers down awhile. The Maverick is quicker to go up & quicker to come down. It's just the nature of the beast.

I don't really worry about what the MES reads. I only use it to get me into the ball park. I put the Maverick next to the meat, and go by that. Then I make adjustments going by the Maverick.

It doesn't matter what the temp is where that #2 Temp Sensor is. It matters what the temp is where you have your meat.

Sometime try sticking the tip of your remote probe about an inch from that #2 temp sensor, and see what they read then, for a few cycles.

BTW: I see your problem, if you can't set it higher than 275˚, and your MES is 20˚ lower than actual, you really are only able to set it at 255˚, but try that "Sticking that tip of your tested remote probe within an inch (not touching) of that sensor" and see what happens through a few cycles.

Bear


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## tjohnson

My 1 year old 40" MES is off 15° on the hot side, compared to a brand new maverick ET-732 and my "Brand New" 40" 40" MES is off 20° and warmer temps, but at freezing temps, it's off 32°.  i use it only for reference and use a Maverick ET-732 for real temps.

Todd


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## doctord1955

what is your high and what is your low temp as smoke cycles?


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## Bearcarver

doctord1955 said:


> what is your high and what is your low temp as smoke cycles?




Normally, mine starts at 2˚ below the temp setting, and shuts off on the temp setting, but if it's real cold & windy out, it may drop a few more degrees lower, after the element kicks on, and then coast up a few degrees above the setting, after the element shuts off.

I hope that makes sense.

If it doesn't, let me know & I'll try again.

Maybe this is easier to understand:

Set heat at 200˚

On at 198˚

Off at 200˚

Cold & Windy out---Set at 200˚

On at 198˚

Off at 200˚, but coast up to 203˚, after element shuts off.

On again at 198˚, but keep dropping to maybe 194˚ before temp starts rising again.

Bear


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## hkeiner

I placed the Taylor probe close to the #2 probe and saw that the MES controler still showed 20-30 degree higher than the (calibrated) Taylor probe.  This disparity is pretty constant during the entire smoke period. I can not heat the MES up to 275 (when desired) because the controller wont heat the MES up past 245-255 or so (thinking that it is at 275). If the difference went the other way (i.e., the Taylor temp was higher than the MES temp) then I would not bother with this problem since I could easily heat the MES up to 275 when desired.

Back to my original question, can anyone guess if replacing the #2 probe or replacing the controller is more likely to fix this problem? I welcome any guesses based upon prior experience in troubleshooting this type of problem or any technical knowlege on how this whole probe/controller thing works.


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## Bearcarver

Mine is the other way around:

When my MES says 250˚, my other probes say from 270˚ to 290˚, depending on where they are. If I take the MES up to 275˚, the others are at 300˚ or higher.

The remote probes are the accurate ones---This includes the MES meat probe, so other than using the digital to make the settings, I ignore what it says, and go by what the remote probes say. 

   Since yours is the opposite, you can only heat your smoker up to 245˚/250˚ (Actual temp), when your MES is set & reading 275˚. I would contact MBTechguy (Darryl), and explain it to him. Since you checked your remote probe in boiling water, I would think it is your controller, but contact him and see what he says. He will probably send you another controller, but I'm just guessing, because I know how good a rep he is.

Bear


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## garyc

My MES 30 /SS is way off as well. What I thought was 220 deg turns out to be 240. It's OK now that I know about it. I wish there was a way to adjust it though.


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## fife

Yep mine is off also I put some thick foil folded over and place it over the smoke box it seems to even it out very well. I tryed the tile but it did not do well at all.


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## driwash

Fife said:


> Yep mine is off also I put some thick foil folded over and place it over the smoke box it seems to even it out very well. I tryed the tile but it did not do well at all.


Can you please show a picture of how you placed the foil over smoke box and what are the measurements of the foil?  Thanks for the tip.  can you sent that to my message bax also?

Tom


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## uhmgood

i have the MES30 , same problem but i did notice that the longer the cook went on the closer and closer my maverick and the probe in the unit came together in temp. i have almost stopped using the mav and just relie on the one in the unit , when it gets close to what i want i check with an instant read , seems to be working out so far


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## flanntastic

i set my mes 40 @275, i get maverick readings (and it reads boiling water at 212) and it will say from 220 to 245 around the MES


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## Bearcarver

uhmgood said:


> i have the MES30 , same problem but i did notice that the longer the cook went on the closer and closer my maverick and the probe in the unit came together in temp. i have almost stopped using the mav and just relie on the one in the unit , when it gets close to what i want i check with an instant read , seems to be working out so far


Uhmgood,

I have noticed this at times too!

I think it's because during the beginning of the smoke, the meat is cold, and the maverick probes are more sensitive than the MES sensor, so the maverick runs up and down more, and the MES readout tends to stay more steady. Then later in the smoke, the meat is no longer cold, so the Maverick settles down & tends to get closer to the MES temp reading. Hoping you can understand my translation from my brain to my typing finger.

Bear


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## uhmgood

bear , i think your absolutely right , makes sense to me


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## daricksta

I know this is an old thread, but just wanted to add my comments. I have a MES30 and I also use a Food Network thermos made by Taylor and equivalent to their 1471. I calibrated it and found it to be within 2 degrees or so of accuracy at 212 and 32. I stuck the probe through a potato as advised by Todd Johnson and stuck it inside my MES to calibrate its temp. During warm up, the MES digital temp displayed 20 degrees higher than the FN/Taylor. But when it reached my target temp the discrepancy fell to only 2 degrees higher than the Taylor and remained there. During that same session I cooked two racks of ribs, inserting the probe from the Taylor into the ribs on the top rack. The ribs turned out beautifully.

So now, when I use the smoker, I set the digital thermos 2 degrees higher than the actual target temp I want. Since I know the Taylor may be two degrees low, this should ensure I get the temp correct on the smoker. Hope that isn't too confusing.


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## sigmo

Porked said:


> Try placing your Maverick probe in different spots inside the MES, my guess is you'll get different readings, I know I did.


I agree with that!


hkeiner said:


> I placed the Taylor probe close to the #2 probe and saw that the MES controler still showed 20-30 degree higher than the (calibrated) Taylor probe.  This disparity is pretty constant during the entire smoke period. I can not heat the MES up to 275 (when desired) because the controller wont heat the MES up past 245-255 or so (thinking that it is at 275). If the difference went the other way (i.e., the Taylor temp was higher than the MES temp) then I would not bother with this problem since I could easily heat the MES up to 275 when desired.
> 
> Back to my original question, can anyone guess if replacing the #2 probe or replacing the controller is more likely to fix this problem? I welcome any guesses based upon prior experience in troubleshooting this type of problem or any technical knowlege on how this whole probe/controller thing works.


I would not replace a probe when we don't know if there is a problem, and if so, if it's the sensor or the controller that's out of whack.


Flanntastic said:


> i set my mes 40 @275, i get maverick readings (and it reads boiling water at 212) and it will say from 220 to 245 around the MES


Make sure to correct for your elevation above sea level.  Where I live, water boils at about 199 degrees F.

Also, it's quite difficult to compare readings on different thermometers or probes.  So unless you have an excellent way of thermally coupling the two probes under test, and you're accounting for thermal time-lags in the probes, etc., don't get too worried if you get different readings between different thermometers/probes.

I just posted a very long-winded diatribe on this subject here:

http://www.smokingmeatforums.com/t/115382/2012-masterbuilt-smokers-new-30-40-models/180#post_818860

Hopefully it'll be helpful.

That doesn't mean your controller/sensor ISN'T out of whack, but I'm just saying that I've seen this sort of complaint so frequently in our laboratories, that I know how easy it is to think you've got a defective thermometer/sensor/controller when actually, you're just seeing the typical variations from one place to another in an oven (even inches apart).

Unless you go to great lengths to make sure the various thermometer probes are thermally coupled to each other, it's difficult to do a valid comparison.

In my MB 40, the sensor that the controller uses to operate the heater appears to be a slender probe poking in an inch or inch and a half through the back wall about 2/3 of the way up.  Keep in mind that any sensor or thermometer can only report the temperature that it is "seeing" right at that one point.  And that may not be representative of the temperatures elsewhere in an oven, cooler, or whatever.  One would hope that the designers experimented with the position for the controller sensor and chose a place that gives good results.  But who knows?

Anyhow, before doing anything rash, make sure you're performing a valid test on the probe in question.


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## sigmo

After reading all of the posts about the accuracy of the controller's temperature indications in the MES40, I decided I should perform what I consider to be a good test of mine.

I just got this unit, it's a 2011 model, purchased just a few days ago at Sam's Club.  (They do not have the newer version at Sam's yet).

I did this testing last night, so pardon the pictures all taken with flash between midnight and about 03:00.

First, I was incorrect in my recollection of the location of the sensor in my smoker.  It's actually positioned quite low in the cabinet, and pretty much right above the heating elements.  The overtemperature cut-off "snap-disk" control, however, is located higher, and to the left as shown here:








I sometimes see the controller temperature sensors for lab ovens located very near the "outlet" of the heater.  I believe this is done to make it easier to "tune" the controllers for good stability (low or no "ringing and overshoot", but doing this comes at the expense of overall accuracy of the control system because the sensor sees the output of the heater, and thus, underestimates the temperature in the main body of the cabinet.  However, this may also be seen as a benefit because it assures that no part of the cabinet will ever be driven above the setpoint.

This may be the same strategy that MB has used here.  They may feel that it's more "conservative" or "safe" to set things up so that there will be no areas in the smoker that are ever much above the selected setpoint.  But this does mean that other areas may be quite a bit cooler than what the controller "thinks" they are.

As I've pointed out in other posts, you will be very surprised at the variations in temperature between different locations in a typical oven or incubator, even a laboratory incubator or oven.

Regardless of all of that, the question in my mind was:  Does the temperature controller in my smoker read accurately?

I had questioned the readings people were getting and posting in this thread and others because my experience with this sort of thing has taught me that to test any temperature sensor, you must be certain that the sensor under test is really at the temperature you think it is at.  To know this, you must have a way to thermally couple the sensor under test to the reference sensor.  Only if they're both known to be at the same temperature can you draw any valid conclusions.  And this is not as easily done as one might guess.  Just having a probe within a few inches of another probe, in air, can mean very little.  I often measure differences of 20 degrees C or more in "good" ovens with probes that are only a few inches apart.  It's particularly noticeable when you have no active stirring of the air (by a fan or blower).  But you will even find variations that are annoying in incubators or ovens that ARE stirred by fans.  It's a constant source of concern in a laboratory environment where tolerances are tight.

Anyhow, while variations in temperature within a smoker are, of course, a great concern, I'm not addressing that here, except to point out that just putting a probe into the smoker and comparing what it reads against what the smoker's controller reads will always be an exercise in frustration and won't tell us if the smoker's probe/controller is accurate.  We haven't controlled all of the variables, so it's not a valid scientific experiment.

OK, so I wanted to make my testing BE valid.

To that end, I did the following:

First, I found a temperature probe that was very tiny and had a cable on it that was small in diameter so I could just slam it in the door of the smoker.  Then I tested the calibration of this probe and its readout to make sure it was accurate.

I used a dry-block calibrator that I built a few years ago for the purpose of calibrating thermometers and electronic sensors.  Basically, it consists of a large piece of machined aluminum that is surrounded by a "band heater'.  The heater is controlled by a little PID controller and solid state relay.  That controller reads a platinum RTD that is embedded into the aluminum block from the bottom, very near the bottoms of all of the various "wells" in the block.  That whole assembly is mounted to two sheets of teflon to provide thermal insulation along with mechanical stability.  Then all of that is surrounded by fiberglass insulation so the heater will not need to work hard once the block is up to temperature.  The block is big and massive, and well insulated, so it has a long thermal time constant.  The aluminum is a good thermal conductor so that, at least when the temperature of the system is not changing much, the temperature throughout the block should be quite uniform.  It won't be perfect, but it's darn good!

The idea is that I can place electronic probes into various "wells" in the block, and know that they're all going to be at pretty much the same temperature.  There is also a central well that I can fill with thermal oil for testing liquid-in-glass thermometers or odd-sized/shaped electronic probes.

I use a precise electronic calibration thermometer as the "transfer standard" to compare against the sensor(s) under test.  That reference calibration thermometer system is calibrated and certified annually and the certification is NIST traceable.  It's rated to be within + or - 0.015 degrees C from -50 to +200 °C.

I used this setup to test the thermocouple probe/readout system before using that thermocouple/readout system to test the smoker's probe/controller.













It was good enough.  I tested it at room temperature, too, and it was dead-on.  Great!

Then, at home, I attached the tiny thermocouple to the smoker's sensor:






	

		
			
		

		
	
   
	

		
			
		

		
	







I just held it up against the smoker's sensor and wrapped that all up with a strand of tinned copper wire to get the two in good contact.

Then I wrapped all of that up in aluminum foil.  The idea was to make sure that both sensors "see" the same temperature at the same time.







It looks crude and ugly, but it ought to do the job well enough.







I had enough wire on the thermocouple to reach up out of the smoker, but just barely.  :)

So I shut the smoker's door and started testing.  I first checked at the ambient temperature, and was pleased to see that both systems agreed well enough:







But then, as I increased the temperature, what I found was kind of strange.  The sensor/controller is quite non-linear.

I allowed the temperature to overshoot the setpoint and then settle slowly down so that I had the lowest possible rate of change of the temperature in the smoker when making the comparison readings.  The lower the rate of change, the less likely issues with the thermal time-constants of the two sensors will cause errors.  We know that the tiny thermocouple I attached to the outside of the smoker's probe will react more quickly than the sensor within the smoker's probe can because there must be some "insulation" between the smoker's probe's sensor and the outer body of the probe itself.  So if the temperature is rising or falling rapidly, there will be a time lag between what my tiny thermocouple sees and what the sensor inside the smoker's probe will see.

Anyhow, when things were reasonably stable at any given temperature, that's when I took a picture to record the temperature readings.

Here's what I got:

Reference Thermometer Reading ----- Smoker Controller Reading

66.8 ----- 66

100.9 ----- 97

131.5 ----- 145

150.3 ----- 166

191.6 ----- 203

245 ----- 262

262 ----- 280

At room temperature, the smoker and reference agreed.

At 100 degrees, the smoker read a bit low.

Then, at all temperatures above that, the smoker read considerably higher than the reference system.

This agrees with what I think most other people have reported here.

If the controller and its sensor were meant to accurately display what the sensor is actually seeing, then the design or implementation is fairly poor.  It's pretty easy to make an electronic thermometer that is quite accurate without spending much money, particularly if you already have a microcontroller at your disposal.  And we know they do because the system has a remote control.

But to give MB the benefit of the doubt, it's possible that they intentionally bias the readings at different temperatures to compensate for what they believe the actual average smoker temperature will be at those temperatures with typical meat loading, etc.  Who knows?

I have not taken things apart to see what kind of temperature sensor is used.  It could be a thermistor, RTD, or thermocouple.  Thermocouples are cheap, rugged, and stand up to a wide range of temperatures.  But they require either a rather baroque analog circuit to "read" them, or a microcontroller programmed to perform the calculations using the multi-order polynomial expression that relates their voltage output to their temperature.  Further, you need another temperature sensor to compensate for the thermoelectric voltage generated at the "cold junction".  This is actually easily done with modern sensor ICs and a microcontroller.  Analog Devices (and maybe others) make ICs specifically meant to "read" thermocouples, so using one of those can provide an easy solution.  But if all of this isn't done properly, you'll get bizarre readings from a thermocouple.  They're non-linear and there will be an unpredictable offset generated by the cold junction connection.

Thermistors sometimes require compensation for their non-linearities, but that can be done very successfully, too, with the right circuit or controller programming.

RTDs are excellent, and again can be read very accurately if things are done correctly.

Semiconductor temperature sensors can be great, but normally won't handle the high temperatures we'd require for a smoker controller probe.

So the real questions I have now are:

Do we really care about the inaccuracies we're seeing in the MB smoker's sensor/controller system?

Are those "errors" actually carefully programmed adjustments meant to compensate for the probe's position in the smoker, and they actually make the system more accurate?  Or are these errors really just errors that we should try to "fix"?

The thing I like about the MB system is the remote control/readout.  I really do like being able to check the temperatures without leaving my easy chair (or even bed) when doing a long smoking.

I could easily install a different probe and a good PID controller.  You can get PID controllers off of EBAY for amazingly cheap.  I haven't tried any of them, but even from Omega, I can get a very good PID controller for under $100.  A solid state relay and a heatsink, some wiring, a sensor, and you've got it all done.  Going the high-dollar route, you might have $150 into the mod.  Shopping on EBAY for a cheap PID controller, you could probably do the job for under $50 for everything.

But you'd lose the remote control feature (not the readout).  That might be perfectly acceptable.  You could wire things so that the remote control could switch the whole thing on and off and still read their sensors, but you'd have to set the temperature on the new controller.  That wouldn't be so bad!  And many PID controllers will do "ramp and soak" which would let you program a routine of different temperatures at different times with "ramping" of the temperature to your desires.

The problem with any proportional control is that you WOULD need a separate smoke generator because with the heater properly proportioned, the temperature of the heating element would often be too low to make the chips smolder.  The advantage of the factory system is that it does cycle the heater on and off, with quite a bit of hysteresis, so that when it comes on, it comes on for long enough to heat up the chip pan and make them smoke.

But I still wonder if there is a method to MB's madness with the apparently crazy non-linearity of their system.  Maybe it is meant to compensate for something.  I kind of doubt it, but who knows?  I wonder what MB has to say about this?

Maybe the point is simply that there are other variables that will render things to be so inaccurate anyhow, that the controller/sensor errors are small in comparison.

The pork butt that I smoked in mine came out fine.  And the internal temperature did what I expected it to do for the smoker temperatures I thought I was getting.

Next, I suppose I should check the probe sensor and its readings! 

If you've read this far, you're either really into this, or a glutton for punishment (as well as smoked meat).  Sorry for the long post.


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## rabbithutch

Howdy Sigmo!

You just KEEP ON adding good advice and content to this forum.  Thank you!

You seem to be very expert in measuring temperatures (and you're and MES owner); so I'm going to ask you about what to do when the sensor stops the heating element from getting power at 275* if you can't get your meat to the desired IT?  It's that upper limit cut-off that can be a killer if the sensor is bad or placed badly or whatever, and stops the heat.

Got any hints or work-arounds that would be safe but would also get the job done?


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## daveomak

rabbithutch said:


> Howdy Sigmo!
> 
> You just KEEP ON adding good advice and content to this forum. Thank you!
> 
> You seem to be very expert in measuring temperatures (and you're and MES owner); so I'm going to ask you about what to do when the sensor stops the heating element from getting power at 275* if you can't get your meat to the desired IT? It's that upper limit cut-off that can be a killer if the sensor is bad or placed badly or whatever, and stops the heat.
> 
> _Got any hints or work-arounds that would be safe but would also get the job done?_


 RH, evening.....  Exceeding the limit cut off temp, as it is pre set, could damage electronics that are hidden in other areas of the smoker....  Every smoker has a learning curve that takes time to adapt to...

Dave


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## sigmo

Hi there.

Last night, I tested my MES40.  Earlier today, I posted a long-winded description of what I did and what I found.  The post is very picture-heavy (I do like photography). 
	

	
	
		
		



		
		
	


	





   I think that because there were a lot of pictures in the post, and I'm new here, that post has been side-tracked for human scrutiny (moderation) before it will show up in the forum.

The short version is that I used a proven-accurate meter with a tiny thermocouple probe, and attached that little probe to the MES's controller probe so that I could be reasonably sure that the two probes would always be "seeing" the same temperature.    I then set the MES for 100, 150, 200, 250, and 275 degrees and noted the readings from the MES's controller and the reference thermometer.

As it turns out, my MES's controller is quite accurate at 68 degrees, reads a bit low at 100 degrees, then suddenly begins to read 15 to 20 degrees high when it gets up to about 135 degrees!  Quite strange.

I won't re-hash everything I said in the other post, because I'm hoping it will show up here before too long.

I also won't put any pictures in this post because it seems as though including photos triggers the mandatory moderation of the posts.

To your question:  If the inaccuracy of the controller/probe in our MESes prevents us from being able to actually achieve a temperature of 275 in the smoker, the best thing would be to somehow adjust or cheat the controller into making a more accurate measurement.  That would maintain all functionality and safety built into the smokers.

Hopefully, the little snap-disk overtemperature limit switches are not the problem in any of these MESes.  If they are, they could be replaced with more accurate ones, but I suspect those are OK.  The snap-disk limit switches are the safety limit in these cookers.  They're really not meant to control the temperature, but rather to shut off power to the heater if the unit gets over some temperature that MB has determined is a safe upper limit.  It looks like they use some type of foam insulation in the units, and that probably has a fairly low upper working temperature.  So we do need to be sure not to get things too hot in there. 

So assuming the problem is with the controller/probe, we then need to understand what's creating that error.  It's interesting that a lot of us seem to have systems where the controller reads too high, but at least one (and probably more) people have units where the controller reads too low.

But again, I caution everyone that its not trivial to make valid tests/comparisons.  So we do need to be sure the measurements are all made properly before we jump to any conclusions.

I need to take the unit apart, make some measurements, and take a close look at the controller's circuit board to try to figure out what kind of sensors the system uses and see if I can figure out parts of the circuit that does the measurement of the probes.  It may be that there is already an adjustment on the board.  It may be that we could add an adjustment.

It also may be, as I speculated in the other post, that there is a method to MB's madness, and they intentionally skew the readings from the sensor in order to achieve better real accuracy out in the main area of the smoker.  The shape of the "curve" of the error in my smoker is pretty strange.  And they've got a microcontroller at their disposal, so it would not be difficult (or expensive) for them to make it quite accurate - if that's what they want.
 

I'm going to check to see if my other post has made it through yet.  
	

	
	
		
		



		
		
	


	





Edit to add:  It did.  It's up above this, as post #21.


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## mattj2006

This is just a shot in the dark but after looking at you photos I have a half smoked theory.  Would different ammounts of contact between the sensor and the material the internal walls are made of cause the wild differences we see between everybodys MES's?  Essentially the probe is coupled to the internal wall if it is touching it correct?  Maybe insulating the probe from the wall ,ie. routing the hole out a few mils, would provide better accuracy.


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## sigmo

mattj2006 said:


> This is just a shot in the dark but after looking at you photos I have a half smoked theory.  Would different ammounts of contact between the sensor and the material the internal walls are made of cause the wild differences we see between everybodys MES's?  Essentially the probe is coupled to the internal wall if it is touching it correct?  Maybe insulating the probe from the wall ,ie. routing the hole out a few mils, would provide better accuracy.


That is a good observation, and something that does need to be considered when one designs a temperature measuring or control system.  There's a whole science of designing what they call "thermowells" for use getting measurements where the sensor needs to protrude into a pipe or chamber.

Ideally, the way a probe of this nature is built, the actual sensor is placed as near to the end of the probe housing as possible, or even touching it.  The sensing should be happening right out near the tip of the probe housing.

The sheaths are usually stainless steel tubes that have been spun closed and TIG welded at the end, then ground to form a nice, smooth tip.  Inside, it's just a closed-off tube and it might be a bit thicker right at the tip, but hopefully not too much thicker, so the actual sensing element can still be placed fairly close to the tip we see from the outside.

Stainless steel is only a fair conductor of heat.   So ideally, the thermal conduction down the length of the tube is fairly low compared to the conduction straight through the walls of the tube to the sensor element.  It's always hoped that the contact you're talking about will have a minimal effect.  But I agree that MB has kept the probe penetration into the smoker quite short, and the conductivity of air to the probe is a lot lower than the conductivity of steel to steel at the hole you're talking about.

Normally, when I set something like this up, I opt for a LOT more penetration.  Sometimes the probe manufacturers will recommend some number of probe diameters of protrusion into the area being measured, and this will be different for air than, say, water.  Air being the worst conductor of heat, and requiring the deepest penetration to avoid "wall-effect".  But I suspect that MB wanted to keep the probe stubby to avoid people ending up with it touching some meat or being knocked around and bent or broken off easily.  So it's a difficult tradeoff.  I'd have gone with a probe sticking in at least two inches.  But then I'd have to be very careful not to damage it whenever working inside the smoker.  I suspect MB doesn't want any more service calls than they have to have, so mechanical strength trumps ideal sensing in this case.

However, we also hope that the inside walls of the smoker are close to the smoker air temperature due to the insulation being pretty good, too.  And it may be felt that really, the wall area around the probe is just as legitimate of a "sensor position" as the probe itself.  So if it picks up some wall influence, that may be just fine, or even a design feature that's been calculated into the whole overall design.

But your concern is really the consistency of this coupling from the wall to the probe from one person's smoker to the next.  And that's a legitimate issue.  But:

If we open the hole a bit, the bracket that mounts the probe (probably part of the probe itself - welded to it right behind the wall) would still be in very good contact with the probe and the wall, so right behind the wall, we've got a bracket with excellent contact to the probe anyhow.  That would tend to make all of the units behave about the same by tying the probes thermally to the walls in a fairly consistent way.

When I did my experiment, the tiny thermocouple I used should have tracked the temperature of the smoker's probe, right about where the sensor should be inside of the probe.  Because of the tiny mass of my probe and how it was coupled to the sheath of the smoker's probe, what I ended up measuring with my little thermocouple should have been the temperature of the smoker's probe's sheath.  (I hope that makes sense).

So, what I set out to do was to see if the smoker's probe/controller system was reporting the actual temperature of the smoker's probe.  This completely ignores the issue you've brought up of whether or not the probe "sees" the air temperature in the smoker.  My experiment, hopefully, reduced the variables to only the one I was interested in testing.  In a sense, I didn't care, for the purposes of this one experiment, whether the probe was properly designed or mounted.  
	

	
	
		
		



		
		
	


	





That doesn't mean that we should ignore all of that, however!  It really is important.

BUT, the thing I was testing, and what I found with mine, was that the smoker's probe/controller doesn't even properly report the probe's temperature.  Nevermind that the probe may not be designed or mounted ideally, it doesn't even report its own actual temperature accurately.

For me, the starting point has to be that the probe/readout system has to be accurate in and of itself.  Then you have to worry about positioning it properly and, as you point out, making sure that the design of the probe and how it mounts assures that you're reading what you want to read (in this case, the smoker's internal air temperature).

BUT, again, you make a good point about just trying to explain the differences we see reported by different people for different smokers.

I haven't taken the back off of the smoker to see what the back end of the probe looks like, but based on the screw we see right next to the probe, I'm guessing that what we'd see is that the probe tube pokes through, and is welded to, a flat steel bracket.  That bracket has another hole in it for the screw to grab.  So even if the probe hole is not touching the probe the same way in everyone's smokers, the flat surface of the brackets are tightly clamped to the back wall of the smoker in every case, so we probably get about the same conduction of heat from the smoker's back wall to the probe tube in every smoker - if you see what I'm getting at.

I tend to suspect two possible other reasons for the discrepancies we see from person to person/smoker to smoker.

First, just us measuring things differently.  If everyone did the experiment exactly the same way, we would eliminate that very large potential error.  But we know we haven't, so we haven't eliminated all of the other variables, so we don't have a valid scientific experiment.  Instead, we've got a lot of anecdotal reports where everyone has done things their own, different way.

Second, I would not be surprised to find that there are some wacky inconsistencies in the controllers or the sensors MB has used.  There really may be the kind of varying errors that have been reported!

So I think you've got a good point about whether the probes are really measuring what we wish they were measuring (air temp only, with no "wall temp" influence).  But I think that they may all be doing about the same thing in that regard due to the bracket factor.  But again, I have not looked inside the back to know exactly how they are built, so you can take my thoughts on the matter with a big grain of smoked sea salt!


----------



## justint

> Originally Posted by *Sigmo*
> 
> Reference Thermometer Reading ----- Smoker Controller Reading
> 
> 66.8 ----- 66
> 
> 100.9 ----- 97
> 
> 131.5 ----- 145
> 
> 150.3 ----- 166
> 
> 191.6 ----- 203
> 
> 245 ----- 262
> 
> 262 ----- 280
> 
> At room temperature, the smoker and reference agreed.
> 
> At 100 degrees, the smoker read a bit low.
> 
> Then, at all temperatures above that, the smoker read considerably higher than the reference system.
> 
> ...
> 
> But to give MB the benefit of the doubt, it's possible that they intentionally bias the readings at different temperatures to compensate for what they believe the actual average smoker temperature will be at those temperatures with typical meat loading, etc.  Who knows?


Good. So this correlates fairly well with my initial findings. I doubt it if MB intentionally bias anything. Personally I don't believe we can expect better from smokers at this price point but they could have made it far more usable at no extra cost. If they read this, may be 2013 model.

The 2[sup]nd[/sup] time I cooked with the 2012 MES30 I recorded the following (from 4 probes)

ThermoWorks meat probe/ MES meat probe, ThermoWorks oven/MES set temperature

55, all 4 probes read  to within ½ degrees

76/82 (delta = 6 degrees), 228/265

109/120 (delta =  11 degrees),  235/270

133/154 (delta =  21 degrees)

I trusted the TW probes and cooked accordingly. MB could have chosen to calibrate at a higher point more relevant to cooking temperatures, like at 133. Who cares if it’s accurate at 55 degrees.

Below are the probes I used . The ceramic fiber probe is flexible so can be looped through rack and positioned near meat.

*For meat probe: *

*“Thermoworks* *Smoke House Penetration Probe - Stainless Armour* *Model: 113-178*

Penetration probe used by commercial smokehouses.

*Accuracy**:* ±0.9°F (±0.5°C) from 32 to 212°F (0 to 100°C) “

*For oven temperature – positioned about 2-3 inches from meat*

*“High Temp Flexible Ceramic Fiber-Insulated Probe*

*Model: WD-08467-64/WD-08467-64-10*

The High Temp Flexible Ceramic Fiber Insulated Probe is used in commercial ovens and furnaces.

*Accuracy**:* ±0.9°F (±0.5°C) from 32 to 212°F (0 to 100°C) “

Monitoring is via the *Two-Channel Thermocouple Thermometer with Alarm #TW8060. *Set to alarm at meat probe temperature of 133F (medium rare).

The 2012 model is also limited to 275F setting which means substantially lower max oven temps. Calibrating at 133 would have helped substantially. Of course mine is now calibrated at a couple of points, I just have to mentally add the difference.


----------



## sigmo

I agree that the errors we're seeing in the MB's temperature control probes is probably unintentional.  But it is amazing to find them so far off when it's so easy to make them be very close.

This all got me wondering about the accuracy of the meat probe in the unit, so I did some testing tonight on mine.

Reference Thermometer ----- MasterBuilt's Meat Probe

100.003 ----- 100

126.009 ----- 127

149.855 ----- 151

175.293 ----- 177

200.015 ----- 202

So the meat probe in the MB 40 is plenty close enough for my purposes.  And that adds to the question of why the smoker's temperature control probe would read so far off.  If they can get the meat probe to be fairly accurate, why not the temperature control sensor?  It sure seems like they'd use the same type of sensor so that their controller circuitry would only need to deal with one type of sensor input.

At least I can count on the smoker's meat probe to tell me when various meats are really at the correct internal temperatures.  That's important for food safety.

I also tested a few other cooking thermometers while I was at it.



















The reference thermometer's probe and the little Thermoworks meat thermometer were inserted into the dry-block's dry wells while the probes for the two wired-remote probe alarm type thermometers and the probe for the smoker were all inserted down into the center well which was filled with cooking oil.  I should have gotten a better picture showing how it looks down in there.  It's just a way to thermally couple everything reasonably well.


----------



## rabbithutch

Congratulations on another, most excellent post, Sigmo!

Thank you!

Referencing your results, you say that the calibrating sensor reading 262* produced a reading on the MES of 280*.  Is that correct?

You then point out that the "snap-disk" sensor is designed only to stop power to the heating element when its upper limit is reached (which makes a great deal of sense).  I have been guilty of broad jump logic by assuming that the heating element was turned off by that "snap-disk" sensor.  If I've followed you correctly so far, I must ask how you account for getting a reading on the built-in heat sensor of 280* if that is the part that is controlling the heating element.  Of course, this might be due to some incremental heating that occurred in the air after the sensor reached 275* and shut down power to the heater element.  We don't know.  I think your test results confirm my concerns, and perhaps those of others, about the temperature sensor and how it controls the heating element.  Suppose, for example, that any 2 MES units of the same model might have sensors that vary by as much as 10%, but that the electronics are constant in their treatment of the signals.  My hypothesis is based on an expectation that there is far less variance in the electronic circuits than between sensor units.  (This is a totally uninformed, uneducated guess).  Given those conditions, then it might be possible that my MES sensor reads 10% lower  than the one you tested at the same ambient smoker temp giving me a reading of 288*.  This means - assuming the electronics shut power to the heating element when the sensor crosses the 275* threshold - that additional heat would have been stopped at 249* while reading 288*.  

That is, admittedly, a rather convoluted argument and assumes far too may constants, but I was trying to reconcile observations I've made while using my MES40.  You point out that air is far from the best medium by which to compare readings of different probes.  I defer to your much greater expertise in this matter and have no doubt it is true, but it is hard for me to reconcile a difference between the chamber sensor reading of my ET-73 of 245* and a reading on the MES of 279* while observing that the element heating light is not lit.  Combine a few of those readings with unintended shut downs due to my hitting the remote on/off button and not being aware that an upper limit set too low will shut heat off, and you have meat probe temps that stall or drop.  This is vexing, to say the least.  Yes, much of the damage was self-inflicted.  I'm learning but CRS is a constant companion at my age.  I'm unaccustomed to having similar problems in kitchen oven because one doesn't set both lower and upper limits and one doesn't risk turning one off with the remote.  It is these conditions that cause me to be dissatisfied with the electronic controls and sensors on the MES.  They may or may not suffer from defects and or quality control issues, but I contend that the electronics should display information more readily understood by anyone standing within 1/2 SD of the apex of the IQ bell shaped curve.  The frustration comes from the knowledge that the technology exists and that incremental production costs would be nil.  It seems to be that only the R&D costs for connecting the IC's and other components are the problem.  Those costs, amortized on large numbers of units sold must also be relatively insignificant.

Sorry for being so long-winded, but this subject - and your ability and willingness to run the experiments for us - will help all of us become better smokers and might even help MB produce better products in future.  If you need a challenge for future experimentation, I suggest that you track sensor readings against a calibration standard sensor and record the points at which the heating element is powered.  I would really like to know to what temperature it will continue to heat with my upper temp setting at maximum.

Thanks again for such excellent contributions here!  Thumbs UpThumbs Up


----------



## hkeiner

Excellent information. I previously thought the primary reason for the disparity between my MES's temperature reading and my Maverick's temperature reading was due mostly to the different  locations of the probes. That is, the temp along the back wall just above the element (where the MES probe is located) was that much higher than the temperature on the middle rack (where the Maverick probe was located) due to the different thermal/radiant heat conditions between these two locations. This explains why my previous attempts to compensate for this (by placing heat shields such tiles, aluminum foil, deflectors, etc along the back right corner of the MES) had limited success in reducing this disparity. I am still very happy with my MES anyway, as all I need to do is set the MES about 20 degrees higher than the desired temperatue and then monitor temps using the Maverick.


----------



## sigmo

rabbithutch said:


> Congratulations on another, most excellent post, Sigmo!
> Thank you!
> Referencing your results, you say that the calibrating sensor reading 262* produced a reading on the MES of 280*. Is that correct?
> You then point out that the "snap-disk" sensor is designed only to stop power to the heating element when its upper limit is reached (which makes a great deal of sense). I have been guilty of broad jump logic by assuming that the heating element was turned off by that "snap-disk" sensor. If I've followed you correctly so far, I must ask how you account for getting a reading on the built-in heat sensor of 280* if that is the part that is controlling the heating element. Of course, this might be due to some incremental heating that occurred in the air after the sensor reached 275* and shut down power to the heater element. We don't know. I think your test results confirm my concerns, and perhaps those of others, about the temperature sensor and how it controls the heating element. Suppose, for example, that any 2 MES units of the same model might have sensors that vary by as much as 10%, but that the electronics are constant in their treatment of the signals. My hypothesis is based on an expectation that there is far less variance in the electronic circuits than between sensor units. (This is a totally uninformed, uneducated guess). Given those conditions, then it might be possible that my MES sensor reads 10% lower than the one you tested at the same ambient smoker temp giving me a reading of 288*. This means - assuming the electronics shut power to the heating element when the sensor crosses the 275* threshold - that additional heat would have been stopped at 249* while reading 288*.
> That is, admittedly, a rather convoluted argument and assumes far too may constants, but I was trying to reconcile observations I've made while using my MES40. You point out that air is far from the best medium by which to compare readings of different probes. I defer to your much greater expertise in this matter and have no doubt it is true, but it is hard for me to reconcile a difference between the chamber sensor reading of my ET-73 of 245* and a reading on the MES of 279* while observing that the element heating light is not lit. Combine a few of those readings with unintended shut downs due to my hitting the remote on/off button and not being aware that an upper limit set too low will shut heat off, and you have meat probe temps that stall or drop. This is vexing, to say the least. Yes, much of the damage was self-inflicted. I'm learning but CRS is a constant companion at my age. I'm unaccustomed to having similar problems in kitchen oven because one doesn't set both lower and upper limits and one doesn't risk turning one off with the remote. It is these conditions that cause me to be dissatisfied with the electronic controls and sensors on the MES. They may or may not suffer from defects and or quality control issues, but I contend that the electronics should display information more readily understood by anyone standing within 1/2 SD of the apex of the IQ bell shaped curve. The frustration comes from the knowledge that the technology exists and that incremental production costs would be nil. It seems to be that only the R&D costs for connecting the IC's and other components are the problem. Those costs, amortized on large numbers of units sold must also be relatively insignificant.
> Sorry for being so long-winded, but this subject - and your ability and willingness to run the experiments for us - will help all of us become better smokers and might even help MB produce better products in future. If you need a challenge for future experimentation, I suggest that you track sensor readings against a calibration standard sensor and record the points at which the heating element is powered. I would really like to know to what temperature it will continue to heat with my upper temp setting at maximum.
> Thanks again for such excellent contributions here! Thumbs UpThumbs Up


Here is the thing I probably have not explained well enough:

The snap-disk temperature switch is a "last ditch" or "emergency" shut down device. It is wired in series with the heating element AND the power relay that actually controls the heater.

Effectively, there are TWO devices that can control the power to the heating element.

This is commonly done to provide safety in heating appliances.  The snap-disk is not normally the part that will control the smoker's temperature (but it can in an emergency).  Instead, it's there just in case the sensor goes bad, the controller goes wild, or the power relay's contacts weld closed (or, if it's a solid state relay, it breaks down and shorts - triacs and SCRs tend to fail shorted).

In any of those scenarios, the heating element would be powered on "solid" and the temperature in the smoker would climb uncontrollably.  In such a situation, when the snap-disk reaches its cut-out temperature, it would open the circuit and kill power to the heater.  Snap disks can be bought with various "cut in" and "cut out" temperatures.  They often have a very wide temperature gap between their cut in and cut out temperatures.  But in this case, we don't care.  It's just meant to prevent a runaway and keep the smoker from burning itself up.  I think the insulation in these smokers may be one of the things that they worry about if things were to get too hot.

So under normal operation, we'll never see that snap disk do anything.  It's just a constantly closed switch in series with the heating element that's there in case of dire overheating.  Then it'll pop open and keep the smoker from damaging itself or burning up.  I have not had the cover off of the smoker, so I have not looked at the back side of that snap disk, and don't know for what temperature it is rated.  They're usually marked, and even if the number doesn't directly tell you, you can look up that model of switch and see what the specs are.  I'm guessing, maybe, (speculating, actually) that they're chosen to trip off at, perhaps, 350 degrees or something.  That way, they won't trip unnecessarily, but they will stop the smoker from catching on fire.  :)

So, under normal operating conditions, that snap disk doesn't enter into the control picture.

Instead, the smoker's electronic controller switches the power on and off to the heating element based on what it reads from that slender little probe sticking into the back of the unit down lower.

What I tested was the relationship between that little probe's actual temperature and the reading we see on the smoker's controller.  When that sensor was at a real temperature of 262, the display on the smoker's controller was showing 280.

From observing mine, the smoker puts full power onto the heater until the display on the smoker reaches the temperature I've set it for.  Then the power to the heater is switched off immediately.  The temperature will then "coast" upwards beyond that point because of the thermal energy stored in that red-hot heating element.  We call this "overshoot" in control systems.

I haven't studied exactly when the heater is turned on, as the temperature read by the controller drops down below the setpoint, but I think they just switch it on as soon as the display reads anything below the setting.  I'll check that out sometime.  Often, in a control system, you'll build in some "hysteresis".  A purposeful difference between the trip-on point and the trip-off point.  That hysteresis prevents the heater or cooler from cycling on and off too quickly.  Rapid cycling wears out control relays (in the case of a non-solid-state relay) and in a chiller situation, it'll wreck the chiller's compressor.  So sometimes we'll build in a fairly wide hysteresis  or "dead band" to limit how fast things can cycle.

This type of operation is usually called "bang-bang" control.  The heater is either fully on or fully off.  And you get temperature cycling as a result of the stored energy in the heating element carrying the smoker's temperature above the setpoint every time the heater is switched off by the controller even if they have NO hysteresis built into the controller.  There's nothing really wrong with this.  Almost all ovens do this.  Things don't need to be all that perfect to still work OK.

Better would be a proportional control for the heater, but if you had that, the heating element would almost never get hot enough to make the wood chips smoke.  This is one of the design tradeoffs that they must make for this design of smoker.  You want decent temperature control in the chamber, but you've also got to assure that you really put the heat to the smoking chips every so often to keep them smoking.  With a proportional control, you would throttle the power to the heater continuously so that it'd run at a low power all of the time.  That exact power level would be maintained "proportional" to the error between the actual chamber temperature and the setpoint.  The farther below the setpoint the temperature read by the sensor, the more power would be applied to the heater.  So when things reach a steady temperature just below the setpoint, the power to the heater would be fairly constant, and presumably fairly low.  So you wouldn't get any smoke except right at the first of the run when the heater runs at full power for a short time to get the smoker up to near the setpoint you've set.

So they actually rely on the hysteresis or temperature cycling of the chamber to get some smoke now and then as the controller switches the power on each time.  You almost need to have bad insulation in the cabinet to enhance the smoke generation.  This is why one of the aftermarket smoke generators seems like such a good idea to me, and I've got an Amazin unit on order myself!

OK, that's getting a bit off track from your questions, I guess, but it's important in analyzing why MB does things the way they do.

Your concern about the accuracy of the sensors and/or electronic controllers is a very valid one.  Sensors can be inaccurate and have wild variations from one example to the next of the same make and model.  But sometimes, they're actually very good so that they can be substituted for each other in some systems without any need for calibration of the system.

The electronics, likewise, can be made to be very accurate "right out of the box" OR they can be made with parts that have a very loose tolerance, and thus require some type of calibration to get things right.  In the past, electronics that needed to be very accurate were made with tight-tolerance parts and then had an adjustment of some sort to tweak things in.  Newer designs often use good tolerance parts, but leave out the manual potentiometer or other "hand" adjustment because hand-adjusting things requires (usually) human time and labor, and that's expensive.  So lots of modern electronic controls are adjusted automatically by changing stored data used by a microprocessor or microcontroller.  That allows for easier automation of the adjustment process.  Or the tolerances of the voltage references and other components are just so good that for normal use, no adjustment is required.

These MESs are kind of disappointing.  It seems that they're not very accurate for whatever reason.  I have not had the controller apart.  I just put my smoker together and started using it right away.  I will take it apart and see what I can find out from looking at things.  I would not make any guess as to whether the controllers or the probes are to blame for the strange deviations we're seeing in these units.

Further, the fact that the meat probe on mine is so accurate while the smoker temperature probe seems to be so far off (and non-linear) is mysterious, too.  If they can get it right for one of the probes, why not for both?  They're both important.

When you get a reading of 279° on the MES display while your ET-73 shows 245°, it's possible that you're seeing two things at once.

First, your smoker's sensor and electronics might be almost exactly like mine, reading about 18-20° higher than what the probe is actually experiencing.  Then second, you may also be seeing exactly what you've described where the temperature of the smoker's probe, being right above the heating element, IS seeing a falsely high temperature that is not representative of the temperature elsewhere in the smoker chamber.  Then again, your smoker's probe/controller might be off farther than mine is!

And, you'd see this worst-case discrepancy for the time right after the smoker's heater has just been shut off by the controller.  Say the controller switches the heater off right when it crosses the 275° threshold.  But there's still a lot of residual heat stored in the heating element.  The temperature seen by the smoker's probe will continue to "coast" upwards, (overshooting the setpoint).  And that's the time when you'll see this very high temperature reported by the MES controller, but your good thermometer, placed elsewhere, may be seeing the "real" temperature in the main area of the chamber so now you've got that wild difference.

If the smoker's controller actually displayed, and controlled based on, the REAL temperature of the little probe, I would not be all that concerned about reading lower temperatures elsewhere in the cabinet.  I'd chalk that up to the design of the system, and figure it was OK for that to be observed because the manufacturer was trying to be conservative and prevent the smoker from ever being a lot hotter than it ought to be, even in areas closer to the heating element.  There will always be some differences in temperature from place to place in the smoker.  And with a probe near some meat, it may read quite a bit lower because the meat itself is cooling the air next to it as it absorbs the heat energy from that air.  That's always going to be the case in any oven or smoker.

A convection oven (oddly named IMO because they do NOT rely on convection, but instead on forced air flow) would be a lot different.  The forced air would be closer in temperature from place to place in the oven.  Still not perfect, but closer.  It'll also cook a lot faster for any given temperature because of this.  The air temperature right at the meat will be close to the actual oven setting, so the meat is really "seeing" a much higher temperature in a convection oven than it would in a "regular" oven set to that same temperature.  This is all normal and expected, and it's why you shouldn't get too upset when you measure temperatures, with a separate probe, near some wet, cooking meat, that is lower than the oven's set temperature.

But again, what I measured in my MES was a discrepancy between the oven probe's temperature and the temperature displayed on the controller.  I don't like that at all.

Maybe I can find a way to make an adjustment in the electronics or in the probe's wiring to dial things in better.  But the non-linearity is concerning.

Also, if people's MESs behave the way ours do, then we cannot actually get the ovens up to 275°.  The highest I figure I can achieve will be about 257°, and that's not counting the effect of the probe being right above the heater.  Still, it would make me happy if the controller simply reported the actual temperature of the probe - to within a few degrees, anyhow.

I'll certainly report back here if I take things apart and learn any about what kind of sensor they're using and what, if anything, we can do to adjust things better.


hkeiner said:


> Excellent information. I previously thought the primary reason for the disparity between my MES's temperature reading and my Maverick's temperature reading was due mostly to the different  locations of the probes. That is, the temp along the back wall just above the element (where the MES probe is located) was that much higher than the temperature on the middle rack (where the Maverick probe was located) due to the different thermal/radiant heat conditions between these two locations. This explains why my previous attempts to compensate for this (by placing heat shields such tiles, aluminum foil, deflectors, etc along the back right corner of the MES) had limited success in reducing this disparity. I am still very happy with my MES anyway, as all I need to do is set the MES about 20 degrees higher than the desired temperatue and then monitor temps using the Maverick.


I do think the probe positions will greatly affect what we read.  So your thinking has been right.  But it also appears that (mine at least) also just reads too high for what the probe is actually seeing.

The problem with setting things about 20° above what you really want would be if you do want to cook at a temperature of 275.  We really can't ever get that if all of our units are reading 20° too high.

I wonder if they're all about the same amount off, or if it varies a lot.  I'd love to have more data, collected by thermally coupling our "reference thermometers" directly to the MES's probes.

If they're all off the same way, and given how good my MES's meat probe seems to be, then it makes me wonder even more if the "errors" we're seeing aren't being done on purpose.  It doesn't seem right.  I would like to know what a bunch of other people see when they couple their MES control probe to a known-good thermometer.

Maybe I'll swipe the controller back off of the top of my MES and take a look inside of it tonight.


----------



## stovebolt

I get similar results to what you get when I place a known accurate thermometer probe near the cabinet probe in my MES40. The cabinet probe reads about 20 degrees warmer then the other thermometer when I'm cooking at about 225. I have to set my controller at 245 to get the temperature I'm after.

  I anxiously await any further information you come up with.

  Chuck


----------



## sigmo

That's good info, stovebolt!

I looked at the back of my MES, and it's pop riveted in place.  So to get to what I wanted to look at, I'd have to drill out the rivets. I'll look closer when I've got some time.  Maybe there's an easier way to get into it.  I don't relish totally voiding my warranty just yet.  I've only had the unit for a week or so!  Then again, curiosity will eventually get to me, I'm sure!

I'm pretty sure I can figure out what is what going to the connectors for the controller board.  I'm curious as to what kind of sensors are in the meat probe and the compartment probe.

Meanwhile, I've got some pork chops that need to be smoked, and I just got my order from A-Maze-N today.  So I'm going to put this gadget to some good use even if it is out of calibration!


----------



## rabbithutch

Sigmo!

You outdo yourself with every post!

Thank you very much!  Your experience and expertise are very helpful to everyone . . .  especially those like me who know so little about the subject.  

Your information will help me be a better smoker!

Thank you for spending the time to answer our questions.

. . .    and don't void your warranty on my account, please.  :biggrin:


----------



## russg

Nice work.   Have you tried the test without the tinfoil?

Have tried sharing this with MB?

thanks for all your research.  MB needs you.

Q to you!


----------



## smoker21

Thank you for taking the time to experiment and share with us your findings.

Your numbers are similar to mine, but I just set mine about 15 degrees lower and eat!

Thanks again.

JD

<<Reference Thermometer Reading ----- Smoker Controller Reading

66.8 ----- 66

100.9 ----- 97

131.5 ----- 145

150.3 ----- 166

191.6 ----- 203

245 ----- 262

262 ----- 280>>


----------



## smoker21

Oh yeah,

 I always use a thermometer before I pull anything out of the smoker!

JD


----------



## stovebolt

Sigmo said:


> That's good info, stovebolt!
> 
> I looked at the back of my MES, and it's pop riveted in place.  So to get to what I wanted to look at, I'd have to drill out the rivets. I'll look closer when I've got some time.  Maybe there's an easier way to get into it.  I don't relish totally voiding my warranty just yet.  I've only had the unit for a week or so!  Then again, curiosity will eventually get to me, I'm sure!
> 
> I'm pretty sure I can figure out what is what going to the connectors for the controller board.  I'm curious as to what kind of sensors are in the meat probe and the compartment probe.
> 
> Meanwhile, I've got some pork chops that need to be smoked, and I just got my order from A-Maze-N today.  So I'm going to put this gadget to some good use even if it is out of calibration!


  I think you will find the main board under the small cover on the underneath of the smoker. Just the element and thermal sensors under the back.

  Chuck


----------



## catpowered

Sir, please take the MES 40 back to where you bought it. I had two in two weeks.  Took both back.  They were horrible quality and Masterbuiltbwanted me, yes me to work on it for them.  Change door, change wood tray, change element then change out cabinet which meant change door again, element again, tray holders, trays, controller, wheels, handle.  Forget it.  A trip an hour to but it, another to exchange that one and another to return it.  I'm done with them and will use a wsm.


----------



## russg

Cat,  what was the model number on the 40.

11, or 12?

Thanks


----------



## hkeiner

> Change door, change wood tray, change element then change out cabinet...I'm done with them and will use a wsm.


Lots of happy MES owners around. Too bad you has such bad luck to have so many things go bad on your MES.


----------



## caldersm

Sigmo,

First....great write up with some very interesting analysis..!!

As to the temperature variance....could it be due to the fact that they might not be linearizing the thermocouple millivolts?  When we bring in a TC as a direct millivolt reading, we have to use a 2 or 3rd order equation.....if you dont, then you get non-linearity in your input readding.  Temperature controllers all do this normally, but maybe they arent compensating for the non-linearity.

Has anyone looked at the control board to see what they are using for the input probe measurement...?  Would be interesting to see what reading they are expecting, and if it is a millivolt signal....then to redirect the probe into a arduino or other chip to compensate for the variances.....Just a thought.

I have an analog MES 30 that I got for $115 at Sports Academy, and I used a Omega Temperature Controller with a K-type TC stuck in the rear air slot.  I used a SSR with a female plug attached to the controller, and I just set the rotary dial to 100% and let the controller do the action.  I found, as you stated earlier in one of your comments, that PID control was too tight, and wouldnt allow smoke, but setting it to On-Off with about 3 degrees of Hysteresis gives great temperature control with LOTS of smoke.

Regards,

Steve


----------



## sigmo

I apologize to everyone for not getting back to this thread in a timely manner.

I haven't actually done too much smoking for a while, either, unfortunately.  But tonight, I've got a big pork picnic butt in the smoker in hopes of using some for pulled pork and the rest for some green chile tomorrow. 

Anyhow, I don't know what kind of sensor MB is using for either the meat probe or the cabinet temperature sensing.  It still seems kind of odd that the meat probe would be so accurate and linear on mine, yet the cabinet temp probe is so far off and so non-linear.  It just seems like they'd use the same sensing technology for both.

Like caldersm points out, if they use a thermocouple for the cabinet probe and don't do the proper calculations to convert its millivolt output to temperature, then it'll certainly be wacky.  There's a lot to making good readings from a thermocouple.  You have to read the temperature at the point where the TC leads connect to the copper wiring of the controller (the cold junction) and then perform the correct CJC (cold junction compensation) and then you also have to deal with the non-linear voltage response of the thermocouple.

But the thing is:  With a microcontroller and program, and with modern IC temperature sensors, implementing a very excellent thermocouple reading system is inexpensive when mass produced.  Yes, the technology is non-trivial.  But once you've designed it and written the code for the controller, the recurring costs to actually manufacture the excellent system are not going to be much.

And again, the fact that the meat probe is so good (within 2 degrees over the whole range I tested) and the cabinet probe is so bad (off by 20 degrees at the high end) is kind of baffling.  Maybe they use a thermistor for the meat probe and their designers did well with that, and then they use a thermocouple for the cabinet probe, and their designers didn't appreciate what was necessary to make that work well.

I still have not taken the controller back off of the top of my smoker to see what's inside of it.  I've been lazy and just using the smoker occasionally and not worrying too much about it.  I just turn it up 20 degrees higher than what I want the cabinet temperature to be, and that makes it pretty close.  That limits my high temperature to about 255, but that's actually hotter than I've needed to go anyway.


----------



## daveomak

Sigmo, morning....  Folks have disagreed with me about the MES temps... When all has been evaluated, the incoming air flow mixing with the heat is not homogenized, and the probed portion of the smoker reads colder  because of this....  Since I have installed the rheostat on the heating element of my MES 30, and adjust it so it maintains a constant temp in the smoker, the temp on the display and the temp at the exhaust are usually within 5 degrees.....  A heat source that is constantly on, will provide a uniform temp throughout the smoker...  My observations anyway...    Kind of like a side firebox smoker... even temps....  Turning an element on and off will never produce even temps.... especially if there is a constant supply of fresh air intake...  

That being said, the average temp, at the grate level where the meat is cooking, is the only temp that is important....   Dave


----------



## sigmo

Hi, Dave.

Good points.

I don't know if you've read all of my long-winded posts earlier in this thread or not.  I admit they're boring.  
	

	
	
		
		



		
			






You're probably right that the position of the sensor in the MES might see some of the air coming into the system and read too cool.  On the other hand, because it's right above the heating element, depending on how the incoming air moves over the heater and out of that area, it might read too high when the element is on.  There's probably no perfect location for the cabinet sensor probe in such a system, especially if the heater is cycling on and off.

My main curiosity at this point stems from what I measured testing my MES.   In mine, carefully controlling things, the temperature reported by the controller is reasonably far away from the temperature that the *probe is actually experiencing*.  So I'm not addressing the variations in temperature throughout the cabinet because I know that won't likely be very even.  I was just testing the responses of the probes themselves.  And what seems odd to me is that the meat probe is quite accurate (within 2 degrees F at every point I tested). But the cabinet probe in mine appears to be about ten times less accurate.

Some of my posts further up in this thread describe what I've tested on mine, how the tests were performed, and some of my observations and questions.

When you say you installed a rheostat to control the temperature, I'm guessing that you mean you've installed a dimmer circuit or maybe a variac (not as likely).  If my assumption there is correct, then what you'll get is constant power to the heater.

That has the advantage that the heater will not cycle on and off.  So you'll get no temperature cycling.  But as we were talking about above, we can only get away with that if we use an auxiliary smoke generator of some kind.  Many of us do, though, so we're free to control the heater any way we want.

The disadvantage of a constant power setup is that you'll have to "ride herd" on the temperature more than if you have a true temperature controller.  But that may be of little or no consequence depending on your weather and how much you're planning on babysitting the system during the cooking.  I'm lazy, and often like to cook overnight while I sleep.  The remote control/readout really makes that fun!  But you can still use that even if you're using a separate temperature (or power) control.  You just can't make adjustments while laying in bed.  
	

	
	
		
		



		
		
	


	





As you point out, what's important is the actual temperature of the cabinet in the area where your meat is.  If we can't trust the cabinet probe that comes with the MES, then using a separate probe that you do trust makes a lot of sense.

I'm actually not all that worried about my MES's sensor/display/controller being off as long as I know how far and in what direction it's off.  So characterizing mine has proven helpful to me because I know what temperature to set to achieve the actual temperature I want. And knowing that the meat probe is quite accurate gives me the confidence to make good use of it.  However, I did run into something today that I wasn't aware of.

I need to test to see if what I think I observed was correct or not.  I was finishing my picnic butt this afternoon, and it was reading 199 degrees IT.  My reading on here told me that I ought to run it up to 205 IT.  So I went out for dinner, and when I got back, it was still reading exactly 199.  Hmmm.  Could it be that the max temp the meat probe can read is 199?  I'm sure the instructions would answer that, but you know how that goes.  Does anyone really read them?  
	

	
	
		
		



		
		
	


	





   I'm also pretty certain that I ran into that when I was testing the calibration of the meat probe, but you know how it is getting old.  It's been more than a week, and I've slept since then, so who knows? 

If it maxes out at 199 and keeps reading 199 instead of reading "OL" or something to tell us that the reading is off scale, then I need to be aware of that!  The butt might have been up to 250 IT, and I'd have never known it!  I might lower myself to read the instructions.  If I have to.  I guess.


----------



## texacajun

Sigmo said:


> These MESs are kind of disappointing.  It seems that they're not very accurate for whatever reason.  I have not had the controller apart.  I just put my smoker together and started using it right away.  I will take it apart and see what I can find out from looking at things.  I would not make any guess as to whether the controllers or the probes are to blame for the strange deviations we're seeing in these units.


This is a picture of the controller board wich is located on the bottom of the MES. I had to scrap off all the protective sealant so that i could read the board better. Mabe this will help.













2.jpg



__ texacajun
__ Jul 31, 2012


----------



## centex99

That is the power board but appears to get the turn on or off signal from the board on top, likely where the temperature display/buttons are...

Sent from my HTC One XL using Tapatalk 2


----------



## rabbithutch

caldersm said:


> Sigmo,
> 
> First....great write up with some very interesting analysis..!!
> 
> As to the temperature variance....could it be due to the fact that they might not be linearizing the thermocouple millivolts?  When we bring in a TC as a direct millivolt reading, we have to use a 2 or 3rd order equation.....if you dont, then you get non-linearity in your input readding.  Temperature controllers all do this normally, but maybe they arent compensating for the non-linearity.
> 
> Has anyone looked at the control board to see what they are using for the input probe measurement...?  Would be interesting to see what reading they are expecting, and if it is a millivolt signal....then to redirect the probe into a arduino or other chip to compensate for the variances.....Just a thought.
> 
> I have an analog MES 30 that I got for $115 at Sports Academy, and I used a Omega Temperature Controller with a K-type TC stuck in the rear air slot.  I used a SSR with a female plug attached to the controller, and I just set the rotary dial to 100% and let the controller do the action.  I found, as you stated earlier in one of your comments, that PID control was too tight, and wouldnt allow smoke, but setting it to On-Off with about 3 degrees of Hysteresis gives great temperature control with LOTS of smoke.
> 
> Regards,
> Steve



Hey, Steve!

What language is that you're writing in?  Is there a translator somewhere?  :biggrin:


----------



## smoker21

In a couple of months go to Sam's and try it again.  I've had mine for a couple of years and the only thing I did to mine was to change the wood tray and that was a FREE upgrade from Masterbuilt!

JD.


----------



## caldersm

LOL.....it is ENG-lish.....tee hee....!!

It is Electrical ENGineering ENGlish.....I will send you the cliff notes next time....hehehehehe

Yeah that board above is the power board....so the thermocouples must be connected to the control board in the upper area.


----------



## catpowered

I do not recall other than it was a a MES40 from SAMs Club.    They still sell them.  I bought a wsm and it has turned everything out absolutley perfect.  Should have bought it from the start.


----------



## sigmo

Hi, everyone.

Again, I've been away for too long and not attended to the replies that have been posted here.

I do need to take the top controller off and look inside to see if there are any clues as to how they're implementing the reading of the temperature sensors, etc.

For now, though, I have to say that I've been getting good results with the MES40, but I do set the temperature higher than what I actually want, based on the measurements I made so that I'll actually get the desired smoker temperature.  That's not that hard to do, and since I haven't needed to go above about 225, I can achieve that.

I am going to do another batch of ribs tomorrow.


----------



## cman55

SmokinAl said:


> Mine is off as well, but the other way. I set it at 215 if I want to cook at 225-230.


This is the problem I have as well with my MES40 Gen2.


----------



## tjohnson

You need to measure the temps on each rack, as they will be different temps

Todd


----------



## tjohnson

I want to bump this thread for more info.....

My 2011 MES cuts out at or around 275°

My new 2012 MES runs all the way up to 309°, before the controller realizes it's hit 275° and turns off

The 1st 2012 MES 40 ran all the way up to 329°, before I shut it down.  I could smell melted plastic

So, here's my fear....

The New 2012 has a faulty controller and/or the "High Limit Switch" is not working properly

I would assume the High Limit Switch should shut down the unit at or around 275°

I posted this a while back

This table shows the max temp of polyurethane foam to be 250°

Is this really a good choice for a smoker that reaches a temp of 300°+??

Does Masterbuilt post a MATERIAL SAFETY DATA SHEET(MSDS) for their products?

I found a MSDS for another Polyurethane Foam Mfg. that states the melting point at 350° - 375°f

Insulation MaterialTemperature Range LowHigh _([sup]o[/sup]C)__([sup]o[/sup]F)__([sup]o[/sup]C)__([sup]o[/sup]F)_ Calcium Silicate-1806501200Cellular Glass-260-450480900Elastomeric foam-55-70120250Fiberglass-30-205401000Mineral Wool03210001800Phenolic foam  150300Polyisocyanurate or polyiso-180-290150300Polystyrene-50-6075165Polyurethane-210-350120250


----------



## smokingrk

The only thing I can add to this info is that I realized yesterday while testing, the temps the top half section of the smoker (2[sup]nd[/sup] GEN 40” MES) ran about 20+ degrees hotter than bottom half, when the element was on. 

I’m now leaning towards a convection / air flow issue correction.

Ordered additional MAV to get a probe on each shelf and will re-run when I replace controller from MB, understanding that we’ll see a few degrees delta between probes as Sigmo noted, but hoping controller will correct the temp control issue, then work on the top half heat issue. 

Smoker Set at 250, controller temp reading 232, bottom racks around 278, 275, top rack already at 302, and element was still on...did not want to let this go more,  although during seasoning I may have over done it and not noticed since my external thermometer was hanging on second shelf from bottom, reading 310, so top half  must have been at 330+, top plastic on door shows two cracks.


----------



## tjohnson

My door cracked too, but it was on the bottom

It's crazy, that your 2012 MES acts exactly like mine

Makes me wonder if the rest of them are acting correctly???

Yesterday, I ran another test

Set the controller to 275°

Placed Maverick probes on top shelf

They read 295° & 300° for most of the day

Not the 329° that my 1st 2012 MES 40 got up to


----------



## smokingrk

I can retry the test to see if the temp goes above the 310 mark on top racks and will have to keep a close watch. 

If I get to it today I'll post a quick note.  Otherwise I'll wait to replace controller and test all at once.


----------



## tjohnson

I don't know if it's the controller or a temp sensor inside

When I called customer service at Masterbuilt for the same issue, they wanted to send me a new cabinet

I had to cut off the cord and the name plate, and send them in

In-turn, they would send me a new cabinet.

The process would take 2 weeks

I declined, and decided to return it to SAMS for a new one instead


----------



## sigmo

That's what I'd have done.  Let MB fix it themselves.  Let us know how the replacement unit is.

I hope MB gets the new ones straightened out. 

Phoned in.


----------



## cman55

Learned a hard lesson with the MES's temp anomalys. I just invested in a Maverick 732 and plan to use it in the future for accuracy and use the MES's readings just as a ballpark. Masterbuilt might want to look into this issue at some point down the road.


----------



## hoity toit

Same problem with mine.,,,,still under warrantee. Only 2 month old. Masterbuilt says if i cut the cord off, pop the nameplate and send proof of purchase they will begin the process of replacing the cabinet and controller...bummer. 2 month old unit have to take it apart and pay shipping to them. i think not.

I use the Mavs 2 of them. I wont be buying from Masterbilt again. Its great they are willing to replace the parts...but I dont understand why I have to disassemble the unit and go thru that hassel. They should issue a prepaid FEDEX call ticket and ship out a new unit. Just my opinion..

For now I'll live with it like all you other folks. :(


----------



## njfoses

Hoity Toit said:


> Same problem with mine.,,,,still under warrantee. Only 2 month old. Masterbuilt says if i cut the cord off, pop the nameplate and send proof of purchase they will begin the process of replacing the cabinet and controller...bummer. 2 month old unit have to take it apart and pay shipping to them. i think not.
> 
> I use the Mavs 2 of them. I wont be buying from Masterbilt again. Its great they are willing to replace the parts...but I dont understand why I have to disassemble the unit and go thru that hassel. They should issue a prepaid FEDEX call ticket and ship out a new unit. Just my opinion..
> 
> For now I'll live with it like all you other folks. :(


Probably not worth the hassle.  The replacement is likely to have the same exact issue.


----------



## hoity toit

njfoses said:


> Probably not worth the hassle.  The replacement is likely to have the same exact issue.


My thoughts exactly . . . . .!


----------



## ratboy5000

Ialso have the same mes40 i was also having heat trouble. I called masterbuilt and they are sending me new components to see if that will help. if not they Said they will replace the unit. i hope it doesn't so i get a new smoker and i'll have a cold smoker for free...


----------



## bigtexun

Sounds like the controller needs to be replaced with a PID, thermocouple and SSR.

Then you can set any temperature, and have a quality controller.  I know that is not what anyone wants to hear, but after reading through this thread, it seems like there is a basic quality problem with the system.

Those of you that have been asked to cut the cord and send in the nameplate for a replacement, should use the remains of the "bad" unit as an excuse for a project to replace the crappy controller with a nice PID based controller.

Of course it's not free...  The PID is around $25 to $35, the termocouple is $6 to $15, and the solid state relay is about $12.  I know you already paid Masterbuilt to do this for you in the first place...  But think of the pride you will have knowing that you did it right...

I'm getting ready to add a temperature controller to my charcoal grill, so I can get better control over the temperature.  My problem is I get the temp just right, then the wind kicks up and causes the temp to shoot up by 50 degrees while I'm sleeping.  I need something that can automatically adjust to changing ambient conditions... but it is nice to also know you have something that is accurate.

But yeah, you need good temperature control, and the full temp range you are supposed to have.

Just keep in mind that the PID will let you set any temperature, so there is a basic safety problem...  So you may want to add a limit switch, like perhaps a snap-disk switch calibrated for 275 degrees, or some other over-temperature control.  Some PID's may have a limit you can set, but a overtemp device would be a good safety measure.


----------



## reinhard

i have a Masterbuilt and i had what i thought was a faulty controler "brain box". up here in Minnesota it gets cold and i grill and smoke all year.  i did the break in for three hours and the next day fixed up about a 10 pound batch of venison summer sausage. to smoke the next day. well i was all excited the next day, stuffed the summer, and went out to get the smoker going.

plugged in the unit and no power on the control panel. no lights nothing. followed the troubleshooting guidelines and everything was fine with power going to the unit. well i unpluged the brain box and called Masterbuilt. told them what happened and they sent a new brain box on it's way. in the meantime i go to a butcher buddy of mine [i'm a former butcher and worked for 35 years].  he and another guy have the same Masterbuilt and had no problems with them for 3 years or so that they had them.

he asked me if i left the brain box outside [control pannel]. i said yes, didn't say anywhere in the book to take it off. he told me to take the brain box in the house because the gel in the digital area froze. thaw it out and put it back on and turn the unit on. i did that and sure enough it worked fine. so now i have two of them.

i'm only saying this incase there are some of you that do have cold climates at some time of the year. if you do have cold winters, make sure you take that brain box in the house with you when not in use. the cold doesn't bother the unit once it's on.  so far i have had no issues with my smoker and am happy with it. it does say in the manuel that temps may fluctuate 10 to 15 deg at times. i found this thread interesting and helpfull in case i run into problems of this sort. Reinhard


----------



## jarhead

Well, I'm glad y'all had better luck with their SUPPOSED Customer Service than I have.

Mine is 3 weeks new and it was the last one that Sam's had.

Brought it home, seasoned it per directions, smoke coming out of the top of the glass. WTF?

Next day, I went to smoke a couple pork butts. Set the temp at 275 and checked the grate temps with the ET-732 after about an hour. 230 max on the hottest shelf.
	

	
	
		
		



		
		
	


	





Since then, I have sent their CS 2 emails and called twice. Nothing!!! It's been 3 weeks.

Sam's has a return policy, this is going back and I will never get another MB product again.

Maybe that's the reason Sam's discontinued carrying them. Too many returns for junk equipment.

JM2C and YMMV

Oh yeah, it shocked the he!! out of me too. Don't touch anything metal unless you like getting zapped.


----------



## linguica

Jarhead said:


> Well, I'm glad y'all had better luck with their SUPPOSED Customer Service than I have.
> 
> Mine is 3 weeks new and it was the last one that Sam's had.
> 
> Brought it home, seasoned it per directions, smoke coming out of the top of the glass. WTF?
> 
> Next day, I went to smoke a couple pork butts. Set the temp at 275 and checked the grate temps with the ET-732 after about an hour. 230 max on the hottest shelf.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Since then, I have sent their CS 2 emails and called twice. Nothing!!! It's been 3 weeks.
> 
> Sam's has a return policy, this is going back and I will never get another MB product again.
> 
> Maybe that's the reason Sam's discontinued carrying them. Too many returns for junk equipment.
> 
> JM2C and YMMV
> 
> Oh yeah, it shocked the he!! out of me too. Don't touch anything metal unless you like getting zapped.


It's hard to believe that CS would ignore a three week old unit that has become a shock hazard. That's solid grounds for a law suit.


----------



## indian george

I am a Custom Knife maker . I built  propane forges. That I use Pids to  control them I use K Type  thermo-couplings and wire. I  can use them on my smoker, toaster oven and etc.I run a solenoid with it too,it  controls the propane flow.Just be sure you use the correct wire , that is compatible with the coupling..


----------



## bigtexun

Yeah, turning things on and off based on temperature is pretty easy to do, from an engineering perspective.  From what I have seen, Masterbuilt has a assembly quality issue, as well as a technical problem with the accuracy of the probes.

Correcting probe inaccuracies should be easy, but not if your probe is reading high, and you want to cook at those high temps.

And regarding the correct wire...  Yeah, all a thermocouple is is a dissimilar metal junction, so a poor wire selection will cause inaccuracies.  The best thing is to get the thermocouple with a long enough lead that you don't feel compelled to add wire to make it longer.  You also want to select one designed for high temperatures so that the insulation can handle the heat.


----------



## bigtexun

Jarhead said:


> Oh yeah, it shocked the he!! out of me too. Don't touch anything metal unless you like getting zapped.


Th3e shock hazard could be a wiring fault in the unit...  But it can also be a wiring fault at the outlet.  Don't these have a grounded 3-wire plug?  If it has a grounded plug, and the ground wire is connected to the chassis, then there is a problem with the outlet it is plugged into.  Check the ground wire resistance to the chassis, or check the connections inside the chassis.

As for poor customer service, you should talk to a couple of the people that got good service...  It may be that they have different contact info than you have.  Sometimes a Manufacturer will change contact info over time, or to certain retailers.  The worst is when they outsource...  But they will typically still maintain the old contact numbers, so if you can get an old number you may get better service.

Another problem with email, is that if their spam filter threw your email away for some reason, you will never hear back from them.


----------



## cman55

Well, my MES40 Gen2's Controller finally gave up the ghost last night. Started to cold smoke some bacon today at around 0730. Outside temp was roughly 25F and dry but my controller read 310F. Ok, so I knew that was way off but I figured the unit must have gotten frozen over night or some moisture got inside the controller housing by some means so, I heated up the unit to 275F just to get the ice out and see if the internal temp sensor would come back online. Unfortunately, it is still waay off. I called Masterbuilt CS and talked with Becky. She very politely told me that the controllers are on back order and to check back in a week or two and they would be very happy to send out a replacement. She also assured me that the replacement work would be simple although I do have my doubts considering the controller is now part of the chassis and not sitting outside of the cabinet in the GEN2.  I must admit that I am disappointed with the quality of this unit as I purchased it for Christmas and babied this thing during several easy smoke sessions. I am hoping that the replacement Controller is indeed a fix and not simply a replacement. 

Keeping my fingers crossed..


----------



## briar

This is just an in general statement, but the more thermal mass the probe has (or is mounted to, its all a heat sink)... the more its going to read avg temps instead of highs and lows.

The built in probe should (under normal conditions) lag the maverick (in both directions) until temp is reached then the two should become closer.

To really check accuracy I would compare the avg temps of the two from readings taken over time.... deadband is another issue, close loop temp control circuits will have some deadband built into the circuit. The maverick doesn't need deadband.

I use to be a sears service man back in the day, and we would have complaints form little old ladies who would hang thermometers in their new oven and see a similar issue.

Once I showed them the math, they were usually happy and understood.

(not saying MES doesn't have an issue, just tossing my prior similar experience out there for what its worth)

B


----------



## sigmo

That's a good point.  Most folks don't understand that the time constants of their temperature probes will have a great impact on what they see at any given moment, and they often expect one thermometer or sensor to read the same as another at all times.  Of course, that's impossible if the temperature is cycling up and down and the probes don't have the same thermal time constant.

One thing to remember, that was not obvious to me at first (but probably should have been) is that the thermal time constant of a probe is not entirely a matter of the thermal mass of the probe.  Instead, it's actually the ratio of thermal mass to surface area that's important.

I proved that to myself and some other very smart laboratory personnel where I used to work one time a number of years back.  We had a room that needed to be kept within some fairly tight temperature limits while an extraction (TCLP) was being performed.  I had initially installed a fairly small temperature probe to monitor that room, and we were annoyed to see the rather wide swings of temperature even though the average was holding what we wanted.

We all reasoned that the small probe was "seeing" much greater temperature extremes than the samples actually saw because the samples were fairly large (1 liter?) bottles full of (mostly) water.  Surely, a large bottle of water will experience a much slower change in temperature than a small temperature sensor probe, right?

I had this probe connected to a data acquisition system that monitored things constantly and allowed us to see things plotted on graphs.

So I got a 500mL (1/2 liter) glass bottle, filled it with water, and made a gland top for the bottle that allowed the same 3/8" stainless probe to be inserted so it was always held with the sensor at about the middle of that bottle of water.  I, and everyone else just assumed that the temperature graph would settle down and show a much smoother temperature curve, with far lower differences between the peaks and valleys of the temperature.

To everyone's astonishment, the chart looked virtually identical to what we were seeing with the probe "bare".  How could that possibly be?

But there it was, right in my face, and I'd made the changes myself.  So the experimental evidence showed that my "postulate" was incorrect.  Faced with that, I thought about it and realized that the thing that allows a probe to "see" a temperature change faster or slower is not the thermal mass.  It's actually the ratio of thermal mass to surface area.  The large glass bottle full of water, indeed, had a much much greater thermal mass.  Water has a high specific heat, and there was a half a liter of it there, that needed to be raised and lowered in temperature!  But the _*bottle's shape*_ was not that dissimilar to the shape of the original probe!

So the *surface area to "thermal mass" ratio* was almost identical, as it turned out!

This also meant that the bottles used for the extractions were, indeed, (and unfortunately) also "seeing" these same extremes in temperature cycling.

I ended up building a temperature controller system for those systems that used a small air conditioner to cool as needed, and an electric heating device to heat when needed.  That keeps those extraction chambers well within the required limits now, but it turned out to be non-trivial, and I learned a valuable lesson about thermal time constants of sensors, bottles, and things in general!

Basically, big and massive doesn't equate to slow.  Again, it's the thermal mass to surface area ratio that's important in determining the thermal time constant of a sensor or a container.  So that gallon jug of milk DOES experience temperature changes pretty much at the same speed as a tiny bottle of jalapenos in my fridge.  And if I have two temperature probes, and they're made of the same stuff, and they're the *same shape*, it doesn't matter if one is a lot larger than the other.  The transfer of heat to and from the sensors to/from the surrounding air will be proportional to their sizes, so the thermal time constants will be the same for both probes.

I'm not sure why that wasn't obvious to me or the other (smart) folks where I used to work.  But it caught all of us off guard until we were forced to think about it by seeing the results of that "experiment" for ourselves.


----------



## Bearcarver

For years, I've been keeping a GatorAde bottle, half full of water in my basement meat fridge. Then I have my Maverick Meat probe in that bottle, I also have the Smoker probe just hanging in the fridge. Then I have the Maverick receiver upstairs in my Dining Room. From there I am able to monitor the temp of the air in the fridge, and the water in the bottle. Once I get the fridge adjusted just right, the air in the fridge cycles from about 32* to 43*, and the temp of the water in the bottle never goes below 37*, and never higher than 38* (perfect curing temps). I do this to monitor the internal temperature of the meat I cure in that fridge, without having to put a probe in the meat. The water in the bottle is the same temp as the inside of the meat.

Bear


----------



## stovebolt

That's a fantastic idea. I will keep that in mind for future use. Thanks, Bearcarver.

Chuck


----------



## Bearcarver

stovebolt said:


> That's a fantastic idea. I will keep that in mind for future use. Thanks, Bearcarver.
> 
> Chuck


It works great !!!

And the batteries last for months, even leaving it on 24/7/365 !!

Bear


----------



## whitvt

Well, I am experiencing the same issue. I have some cheap Hamilton Beach probes that seem to work using the boiling temp and freezer checks. But when comparing them to the meat probe and temperature sensor on the mes I don't know what ones are accurate as they all read different. The last 2 times I have smoked it seems like it has taken forerver to get the meat where I would like the temp to be at. So, now I guess I have to get some good temp probes  and do some checks/comparisons to the mes meat probe and smoker temps. What  pain in the ass. Can't someone just make a good quality product the you can rely on. I bet my smoker is at least 30 to 40 degrees colder than what the controller reads. Time will tell. I got my smoker last year in August.....


----------



## Bearcarver

whitvt said:


> Well, I am experiencing the same issue. I have some cheap Hamilton Beach probes that seem to work using the boiling temp and freezer checks. But when comparing them to the meat probe and temperature sensor on the mes I don't know what ones are accurate as they all read different. The last 2 times I have smoked it seems like it has taken forerver to get the meat where I would like the temp to be at. So, now I guess I have to get some good temp probes  and do some checks/comparisons to the mes meat probe and smoker temps. What  pain in the ass. Can't someone just make a good quality product the you can rely on. I bet my smoker is at least 30 to 40 degrees colder than what the controller reads. Time will tell. I got my smoker last year in August.....


I think you'll find that on just about any smoker with a built in Temp Sensor.

I only trust my Mavericks, because it's easy to do a boil test for accuracy.

It's a shame my Mavericks don't have the distance that my MES Remote control has. My MES remote is usually the only one that works beside my Recliner.

Bear


----------



## dvuong

Most home ovens allow you to calibrate the temperature by pushing a series of buttons.  I wonder why Masterbuilt won't allow you to do the same.


----------



## rimrocksmoker

I have had my 40" that I got at Sams Club for a couple of years.   If I wanted cook at 250, I would set around 220. During the HOT weather we had early this month I was smoking chicken & started out as usual but after keeping the temp I wanted for most of the time, I noticed the temp on my other thermometers was dropping a lot. I would turn the smoker controls as high as I could & internal thermometer would reach that temp while I reality the smoker temp was much lower, which was just the opposite as the way it normally works. The only thing I can think of was that the sun & outside temp was so hot that it affected the MES thermometer.


----------



## Bearcarver

RimrockSmoker said:


> I have had my 40" that I got at Sams Club for a couple of years.   If I wanted cook at 250, I would set around 220. During the HOT weather we had early this month I was smoking chicken & started out as usual but after keeping the temp I wanted for most of the time, I noticed the temp on my other thermometers was dropping a lot. I would turn the smoker controls as high as I could & internal thermometer would reach that temp while I reality the smoker temp was much lower, which was just the opposite as the way it normally works. The only thing I can think of was that the sun & outside temp was so hot that it affected the MES thermometer.


The outside temp being hot can help how long it takes to recover, but it shouldn't have anything to do with running hotter.

In other words if your Smoker shuts off at a setting of 220° or 250°, the ambient temp won't make it go any higher, even if the ambient temp is at 120°.

Bear


----------



## greywolf1

I had a temp. issue as well so the first thing I checked was the temp. probe at the back center of unit ( MES 30 ) . I noticed there was a film on the probe , Mama is now missing one of her scotch brite

pads from her dish sink ( fine pad ) , I cleaned the  temp. probe and the high limit sensor and it was within a couple of degrees from my meat probe. I've gotten into the habit of cleaning both after every smoke.


----------



## Bearcarver

greywolf1 said:


> I had a temp. issue as well so the first thing I checked was the temp. probe at the back center of unit ( MES 30 ) . I noticed there was a film on the probe , Mama is now missing one of her scotch brite
> 
> pads from her dish sink ( fine pad ) , I cleaned the  temp. probe and the high limit sensor and it was within a couple of degrees from my meat probe. I've gotten into the habit of cleaning both after every smoke.


Keeping those sensors clean can be very important.

DaRicksta has been telling people that for a long time.

I keep  mine clean, but I often forget to mention it in my posts.

Bear


----------



## irishpride114

If you buy the Maverick replacement probes on Amazon, they are 6' long each.


----------



## daricksta

Sigmo said:


> After reading all of the posts about the accuracy of the controller's temperature indications in the MES40, I decided I should perform what I consider to be a good test of mine.
> 
> I just got this unit, it's a 2011 model, purchased just a few days ago at Sam's Club.  (They do not have the newer version at Sam's yet).
> 
> I did this testing last night, so pardon the pictures all taken with flash between midnight and about 03:00.
> 
> First, I was incorrect in my recollection of the location of the sensor in my smoker.  It's actually positioned quite low in the cabinet, and pretty much right above the heating elements.  The overtemperature cut-off "snap-disk" control, however, is located higher, and to the left as shown here:
> 
> 
> 
> 
> 
> 
> I sometimes see the controller temperature sensors for lab ovens located very near the "outlet" of the heater.  I believe this is done to make it easier to "tune" the controllers for good stability (low or no "ringing and overshoot", but doing this comes at the expense of overall accuracy of the control system because the sensor sees the output of the heater, and thus, underestimates the temperature in the main body of the cabinet.  However, this may also be seen as a benefit because it assures that no part of the cabinet will ever be driven above the setpoint.
> 
> This may be the same strategy that MB has used here.  They may feel that it's more "conservative" or "safe" to set things up so that there will be no areas in the smoker that are ever much above the selected setpoint.  But this does mean that other areas may be quite a bit cooler than what the controller "thinks" they are.
> 
> As I've pointed out in other posts, you will be very surprised at the variations in temperature between different locations in a typical oven or incubator, even a laboratory incubator or oven.
> 
> Regardless of all of that, the question in my mind was:  Does the temperature controller in my smoker read accurately?
> 
> I had questioned the readings people were getting and posting in this thread and others because my experience with this sort of thing has taught me that to test any temperature sensor, you must be certain that the sensor under test is really at the temperature you think it is at.  To know this, you must have a way to thermally couple the sensor under test to the reference sensor.  Only if they're both known to be at the same temperature can you draw any valid conclusions.  And this is not as easily done as one might guess.  Just having a probe within a few inches of another probe, in air, can mean very little.  I often measure differences of 20 degrees C or more in "good" ovens with probes that are only a few inches apart.  It's particularly noticeable when you have no active stirring of the air (by a fan or blower).  But you will even find variations that are annoying in incubators or ovens that ARE stirred by fans.  It's a constant source of concern in a laboratory environment where tolerances are tight.
> 
> Anyhow, while variations in temperature within a smoker are, of course, a great concern, I'm not addressing that here, except to point out that just putting a probe into the smoker and comparing what it reads against what the smoker's controller reads will always be an exercise in frustration and won't tell us if the smoker's probe/controller is accurate.  We haven't controlled all of the variables, so it's not a valid scientific experiment.
> 
> OK, so I wanted to make my testing BE valid.
> 
> To that end, I did the following:
> 
> First, I found a temperature probe that was very tiny and had a cable on it that was small in diameter so I could just slam it in the door of the smoker.  Then I tested the calibration of this probe and its readout to make sure it was accurate.
> 
> I used a dry-block calibrator that I built a few years ago for the purpose of calibrating thermometers and electronic sensors.  Basically, it consists of a large piece of machined aluminum that is surrounded by a "band heater'.  The heater is controlled by a little PID controller and solid state relay.  That controller reads a platinum RTD that is embedded into the aluminum block from the bottom, very near the bottoms of all of the various "wells" in the block.  That whole assembly is mounted to two sheets of teflon to provide thermal insulation along with mechanical stability.  Then all of that is surrounded by fiberglass insulation so the heater will not need to work hard once the block is up to temperature.  The block is big and massive, and well insulated, so it has a long thermal time constant.  The aluminum is a good thermal conductor so that, at least when the temperature of the system is not changing much, the temperature throughout the block should be quite uniform.  It won't be perfect, but it's darn good!
> 
> The idea is that I can place electronic probes into various "wells" in the block, and know that they're all going to be at pretty much the same temperature.  There is also a central well that I can fill with thermal oil for testing liquid-in-glass thermometers or odd-sized/shaped electronic probes.
> 
> I use a precise electronic calibration thermometer as the "transfer standard" to compare against the sensor(s) under test.  That reference calibration thermometer system is calibrated and certified annually and the certification is NIST traceable.  It's rated to be within + or - 0.015 degrees C from -50 to +200 °C.
> 
> I used this setup to test the thermocouple probe/readout system before using that thermocouple/readout system to test the smoker's probe/controller.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> It was good enough.  I tested it at room temperature, too, and it was dead-on.  Great!
> 
> Then, at home, I attached the tiny thermocouple to the smoker's sensor:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> I just held it up against the smoker's sensor and wrapped that all up with a strand of tinned copper wire to get the two in good contact.
> 
> Then I wrapped all of that up in aluminum foil.  The idea was to make sure that both sensors "see" the same temperature at the same time.
> 
> 
> 
> 
> 
> 
> It looks crude and ugly, but it ought to do the job well enough.
> 
> 
> 
> 
> 
> 
> I had enough wire on the thermocouple to reach up out of the smoker, but just barely.  :)
> 
> So I shut the smoker's door and started testing.  I first checked at the ambient temperature, and was pleased to see that both systems agreed well enough:
> 
> 
> 
> 
> 
> 
> But then, as I increased the temperature, what I found was kind of strange.  The sensor/controller is quite non-linear.
> 
> I allowed the temperature to overshoot the setpoint and then settle slowly down so that I had the lowest possible rate of change of the temperature in the smoker when making the comparison readings.  The lower the rate of change, the less likely issues with the thermal time-constants of the two sensors will cause errors.  We know that the tiny thermocouple I attached to the outside of the smoker's probe will react more quickly than the sensor within the smoker's probe can because there must be some "insulation" between the smoker's probe's sensor and the outer body of the probe itself.  So if the temperature is rising or falling rapidly, there will be a time lag between what my tiny thermocouple sees and what the sensor inside the smoker's probe will see.
> 
> Anyhow, when things were reasonably stable at any given temperature, that's when I took a picture to record the temperature readings.
> 
> Here's what I got:
> 
> Reference Thermometer Reading ----- Smoker Controller Reading
> 
> 66.8 ----- 66
> 
> 100.9 ----- 97
> 
> 131.5 ----- 145
> 
> 150.3 ----- 166
> 
> 191.6 ----- 203
> 
> 245 ----- 262
> 
> 262 ----- 280
> 
> At room temperature, the smoker and reference agreed.
> 
> At 100 degrees, the smoker read a bit low.
> 
> Then, at all temperatures above that, the smoker read considerably higher than the reference system.
> 
> This agrees with what I think most other people have reported here.
> 
> If the controller and its sensor were meant to accurately display what the sensor is actually seeing, then the design or implementation is fairly poor.  It's pretty easy to make an electronic thermometer that is quite accurate without spending much money, particularly if you already have a microcontroller at your disposal.  And we know they do because the system has a remote control.
> 
> But to give MB the benefit of the doubt, it's possible that they intentionally bias the readings at different temperatures to compensate for what they believe the actual average smoker temperature will be at those temperatures with typical meat loading, etc.  Who knows?
> 
> I have not taken things apart to see what kind of temperature sensor is used.  It could be a thermistor, RTD, or thermocouple.  Thermocouples are cheap, rugged, and stand up to a wide range of temperatures.  But they require either a rather baroque analog circuit to "read" them, or a microcontroller programmed to perform the calculations using the multi-order polynomial expression that relates their voltage output to their temperature.  Further, you need another temperature sensor to compensate for the thermoelectric voltage generated at the "cold junction".  This is actually easily done with modern sensor ICs and a microcontroller.  Analog Devices (and maybe others) make ICs specifically meant to "read" thermocouples, so using one of those can provide an easy solution.  But if all of this isn't done properly, you'll get bizarre readings from a thermocouple.  They're non-linear and there will be an unpredictable offset generated by the cold junction connection.
> 
> Thermistors sometimes require compensation for their non-linearities, but that can be done very successfully, too, with the right circuit or controller programming.
> 
> RTDs are excellent, and again can be read very accurately if things are done correctly.
> 
> Semiconductor temperature sensors can be great, but normally won't handle the high temperatures we'd require for a smoker controller probe.
> 
> So the real questions I have now are:
> 
> Do we really care about the inaccuracies we're seeing in the MB smoker's sensor/controller system?
> 
> Are those "errors" actually carefully programmed adjustments meant to compensate for the probe's position in the smoker, and they actually make the system more accurate?  Or are these errors really just errors that we should try to "fix"?
> 
> The thing I like about the MB system is the remote control/readout.  I really do like being able to check the temperatures without leaving my easy chair (or even bed) when doing a long smoking.
> 
> I could easily install a different probe and a good PID controller.  You can get PID controllers off of EBAY for amazingly cheap.  I haven't tried any of them, but even from Omega, I can get a very good PID controller for under $100.  A solid state relay and a heatsink, some wiring, a sensor, and you've got it all done.  Going the high-dollar route, you might have $150 into the mod.  Shopping on EBAY for a cheap PID controller, you could probably do the job for under $50 for everything.
> 
> But you'd lose the remote control feature (not the readout).  That might be perfectly acceptable.  You could wire things so that the remote control could switch the whole thing on and off and still read their sensors, but you'd have to set the temperature on the new controller.  That wouldn't be so bad!  And many PID controllers will do "ramp and soak" which would let you program a routine of different temperatures at different times with "ramping" of the temperature to your desires.
> 
> The problem with any proportional control is that you WOULD need a separate smoke generator because with the heater properly proportioned, the temperature of the heating element would often be too low to make the chips smolder.  The advantage of the factory system is that it does cycle the heater on and off, with quite a bit of hysteresis, so that when it comes on, it comes on for long enough to heat up the chip pan and make them smoke.
> 
> But I still wonder if there is a method to MB's madness with the apparently crazy non-linearity of their system.  Maybe it is meant to compensate for something.  I kind of doubt it, but who knows?  I wonder what MB has to say about this?
> 
> Maybe the point is simply that there are other variables that will render things to be so inaccurate anyhow, that the controller/sensor errors are small in comparison.
> 
> The pork butt that I smoked in mine came out fine.  And the internal temperature did what I expected it to do for the smoker temperatures I thought I was getting.
> 
> Next, I suppose I should check the probe sensor and its readings!
> 
> If you've read this far, you're either really into this, or a glutton for punishment (as well as smoked meat).  Sorry for the long post.


Great investigative and scientific analytical work on your part. But the inaccuracy of the MES controller temp display is why I only go by the temp shown on my Maverick ET-733 receiver which I've previously calibrated. I used the MES controller screen only as a reference point, mainly for enabling me to boost or decrease the set point temp. While I'm at the smoker I'll check the controller temp display against the ET-733 transmitter's display. There are times when if they're not identical they're within 1-2 degrees of each other.


----------



## rimrocksmoker

Bearcarver said:


> The outside temp being hot can help how long it takes to recover, but it shouldn't have anything to do with running hotter.
> 
> In other words if your Smoker shuts off at a setting of 220° or 250°, the ambient temp won't make it go any higher, even if the ambient temp is at 120°.
> 
> Bear


Most times it ran hotter then the temp on the smokers showed. The smoker probe was close to my other probes I used. Later in the day it was just the opposite the smoker was running colder then the smoker controls showed. I was not able to get it up to temp. The smoker controls showed max temp & would turn the burner off. Again the smoker probe was close to my other probes I had to check internal temp. My thought was that maybe there was not enough insulation in the wall behind the sensor. This might cause the sun shining directly on the back of the smoker to cause a hotter reading on the smoker thermostat then the internal temp was. The temp here that day was over 100.


----------



## Bearcarver

RimrockSmoker said:


> Most times it ran hotter then the temp on the smokers showed. The smoker probe was close to my other probes I used. Later in the day it was just the opposite the smoker was running colder then the smoker controls showed. I was not able to get it up to temp. The smoker controls showed max temp & would turn the burner off. Again the smoker probe was close to my other probes I had to check internal temp. My thought was that maybe there was not enough insulation in the wall behind the sensor. This might cause the sun shining directly on the back of the smoker to cause a hotter reading on the smoker thermostat then the internal temp was. The temp here that day was over 100.


The ambient temp of 100° will not make the heat in a smoker go above a 220° or 250° setting.

The only thing the Sun can do is if you have a window in the door, and during the Fall, Winter, or Spring the Sun hits the sensor on the back wall, telling the control that the smoker is hotter than it really is, causing the heating element to shut off, but that kind of thing won't even happen at a 220° or more setting.

The different comparisons you got were from other things, like Air flow, or possibly the wind sucking heat out at times.

*Here's what the Sun can do, but only at lower temps:*

http://www.smokingmeatforums.com/t/101749/mes-with-window-heads-up

Bear


----------



## pepperidge

New to the MES 40" units

tried to do my  first brisket last night and this a.m.  the temp was set at 215 and numerous times I looked @ my bluetooth smarthphone app and the temp was 310*

had to rush outside and open the door until the temp came down enough to resume cooking...

thought it had stopped glitching so i let it cook overnight...bad idea...woke to 322* temps and the brisket was ruined?

Any advice on what could be going on with this unit?

model# 20070115

Thanks

Pepp


----------



## four20

The probes are easily tested, but you have to know the probes OHM's at a certain temperature. Good luck getting that data. The most common reason for probe failure is moisture or inadequate power to the controller. With all electric units I suggest you use a dedicated power outlet. Dirty power is common. Voltage drops will affect the controller, just because you are not tripping a breaker does not mean you have an adequate power supply.


----------



## johnnyb54

Sigmo, I have a quick question. What is that slanted box you have over your side vent?


----------



## Bearcarver

pepperidge said:


> New to the MES 40" units
> 
> tried to do my  first brisket last night and this a.m.  the temp was set at 215 and numerous times I looked @ my bluetooth smarthphone app and the temp was 310*
> 
> had to rush outside and open the door until the temp came down enough to resume cooking...
> 
> thought it had stopped glitching so i let it cook overnight...bad idea...woke to 322* temps and the brisket was ruined?
> 
> Any advice on what could be going on with this unit?
> 
> model# 20070115
> 
> Thanks
> 
> Pepp


#1  If it was set at 215°, and it was up over 310°, I would call Masterbuilt, and explain that to them----They might send you a new controller.

#2  If you're having trouble keeping the heat where you want it, I would not go to sleep with it on.  I've been smoking with 3 different MES units for 7 years and never had a problem, yet I have never gone to sleep while smoking. My house is made of ALL Wood.

Bear


----------



## sigmo

johnnyb54 said:


> Sigmo, I have a quick question. What is that slanted box you have over your side vent?



Sorry to take so long to reply.

In that model of smoker, that is the light in the unit.  The vent on that model is in the top of the box, toward the right rear of the top.  Some newer models have the vent coming out of the upper side.


----------



## johnnyb54

Thanks I always wondered what that was.


----------



## cayotica

The temperature in the MES changes depending how close you are to the exhaust and heat source for best results try to keep your meats in the center of the smoker. Amazing how the temperature sensor just happens to be there. I have the same results as you, I've put four different types of thermometers in my MES AT THE SAME TIME and they all read differently, just trust what the heart sensor says and you'll be okay


----------



## sigmo

And, since there have been a number of changes to the design of these MB smokers over the last few years, observations from one model won't necessarily be correct for another model.  It seems like MB has been constantly making changes, so the positions of the sensors, heating elements, vents, etc., are not the same depending on when and where you bought your smoker.

That makes it harder to offer advice or to compare our observations.  There seem to be pros and cons to the different models that have come out over the years.  So always make sure you're aware of these differences when evaluating advice or observations.   Mine is a relatively old model now.


----------



## cayotica

My MES keeps turning itself off. Will an outlet exposed to the outdoor elements for years cause problems such as temperature fluctuations up to and including turning off on its own with the MES? My major confusion is it's unpredictability it's good for at least 20minutes the it becomes a guessing game when or if it's going to self shutdown.


----------



## Bearcarver

Sigmo said:


> And, since there have been a number of changes to the design of these MB smokers over the last few years, observations from one model won't necessarily be correct for another model. It seems like MB has been constantly making changes, so the positions of the sensors, heating elements, vents, etc., are not the same depending on when and where you bought your smoker.
> 
> That makes it harder to offer advice or to compare our observations. There seem to be pros and cons to the different models that have come out over the years. So always make sure you're aware of these differences when evaluating advice or observations. Mine is a relatively old model now.


Yes---Exactly---We have to find out which MES model people have before we can help with some of the questions.

These links below can help with some of that problem. I keep these links in my Step by Step Index, which is below in my Signature:

*About Masterbuilt Electric Smokehouse (Digital)*

*Masterbuilt Smokers (Bear's Thoughts & Findings)*

*MES Generation Number Recognition Pictures & Pics (Digital Units)*

Bear


----------



## jgruberman

I didn't read the 10 pages of this thread so if this was said, my apologies. 

I had the same issue when I bought mine and Masterbuilt sent me a new control module and heating element to fix the issue. 

Sent from my SAMSUNG-SM-G935A using Tapatalk


----------



## Bearcarver

jgruberman said:


> I didn't read the 10 pages of this thread so if this was said, my apologies.
> 
> I had the same issue when I bought mine and Masterbuilt sent me a new control module and heating element to fix the issue.
> 
> Sent from my SAMSUNG-SM-G935A using Tapatalk


Yes if the heat control problems are beyond their expected ranges they will replace the control unit.

However I believe their book says normal swing temps are  + or -  15°, so that's a 30° swing being expected.

I usually just set mine so that the average temp throughout the cycle falls near the Temp I want to Smoke at.

Bear

Bear


----------



## browneyesvictim

What would you do?

First let me explain... I had been using an older Weber Style 32908 Digital Remote Thermometer for a long time but recently upgraded to a dual probe Maverick 733. The Weber remote was limited on what it can do, and not designed for monitoring pit temps so I never watched pit temps accurately and regularly until now. I knew my Masterbuilt temps were off 15+ degrees- running on the hotter side, so I just set the MB to desired temp to pre-heat while the AMNPS got going good, then lowered it 15 degrees and put the meat and the Amazen in.

Now... Im watching much more closely at what it is actually doing. This time I was smoking a Pastrami and had a desired temperature of 300' so 290+ should be close enough for what I want to do, right? So I cranked the MB up to the max 275' and lit the AMNPS as it warmed up. 275' came and I put in the meat and Amazen. I drop both the temp probes of the Mav down the vent- 1 near the top and 2 near the bottom just to watch temp variations of the smoker.

About an hour later:













Temp.jpg



__ browneyesvictim
__ Nov 28, 2016






...And it stayed around those temps within 10 degrees top-bottom throughout the whole smoke!

While I would like to be close to accurate for the convenience, I also wish the MES was meant to actually smoke at this high of a temperature for certain smokes like this. So... before I go complaining to Masterbuilt... I am debating whether I would prefer the achievement of the higher temps over the accuracy of the unit.

What would you do?


----------



## dr k

Browneyesvictim said:


> What would you do?
> 
> First let me explain... I had been using an older Weber Style 32908 Digital Remote Thermometer for a long time but recently upgraded to a dual probe Maverick 733. The Weber remote was limited on what it can do, and not designed for monitoring pit temps so I never watched pit temps accurately and regularly until now. I knew my Masterbuilt temps were off 15+ degrees- running on the hotter side, so I just set the MB to desired temp to pre-heat while the AMNPS got going good, then lowered it 15 degrees and put the meat and the Amazen in.
> 
> Now... Im watching much more closely at what it is actually doing. This time I was smoking a Pastrami and had a desired temperature of 300' so 290+ should be close enough for what I want to do, right? So I cranked the MB up to the max 275' and lit the AMNPS as it warmed up. 275' came and I put in the meat and Amazen. I drop both the temp probes of the Mav down the vent- 1 near the top and 2 near the bottom just to watch temp variations of the smoker.
> 
> About an hour later:
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> Temp.jpg
> 
> 
> 
> __ browneyesvictim
> __ Nov 28, 2016
> 
> 
> 
> 
> 
> 
> ...And it stayed around those temps within 10 degrees top-bottom throughout the whole smoke!
> 
> While I would like to be close to accurate for the convenience, I also wish the MES was meant to actually smoke at this high of a temperature for certain smokes like this. So... before I go complaining to Masterbuilt... I am debating whether I would prefer the achievement of the higher temps over the accuracy of the unit.
> 
> What would you do?


The dime sized emergency button sensor on the back wall of the Mes is suppose to shut down the smoker a little over 300*F.  It's good you can get up and over the max 275*F.  Some are the opposite and can't get to 275*F. I would stick with the achievement of the higher temps.  I'm not sure if the emergency temp switch trips if it will reset itself after cooling or if it needs to be replaced.

-Kurt


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## Bearcarver

I don't think the Emergency sensor is supposed to kill it at a little over 300°, but I could be wrong.

I had one that went to 332°, and it didn't shut off. I think it might be some higher than 300°.

If it was me, I'd keep that one Browneyes has & just never set it high enough to go over 300° to be safe.

Bear


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## dr k

Bearcarver said:


> I don't think the Emergency sensor is supposed to kill it at a little over 300°, but I could be wrong.
> 
> I had one that went to 332°, and it didn't shut off. I think it might be some higher than 300°.
> 
> If it was me, I'd keep that one Browneyes has & just never set it high enough to go over 300° to be safe.
> 
> Bear


Your right about that sensor needing to be a bit higher from reports when the sensor was activated.  The surface of the sensor has 150*C on it so that's where I got 302*F.  It must be forgiving.  Do you know if these reset after cooling down or need to be replaced once activated?

-Kurt


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## Bearcarver

Dr K said:


> Your right about that sensor needing to be a bit higher from reports when the sensor was activated.  The surface of the sensor has 150*C on it so that's where I got 302*F.  It must be forgiving.  Do you know if these reset after cooling down or need to be replaced once activated?
> 
> -Kurt


I would only be guessing on that, Kurt.

I know that even a good working MES can easily coast more than 25° or even up to 40°, after shutting off at 275°, after a straight run from 70° to 275°.

That's why I wrote that thread about avoiding big over-runs, by setting the control 20° or so lower, and then bumping it up after it stops rising.

Bear


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## brickguy221

Bearcarver said:


> I would only be guessing on that, Kurt.
> 
> I know that even a good working MES can easily coast more than 25° or even up to 40°, after shutting off at 275°, after a straight run from 70° to 275°.
> 
> That's why I wrote that thread about avoiding big over-runs, by setting the control 20° or so lower, and then bumping it up after it stops rising.
> 
> Bear


I set mine 10* lower then bump it up. Works perfect on my 2.5 MES.


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## w2hr

I just like your forum picture they are real boys smokers!!


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## sundown farms

Sigmo - I bow to your hard work and knowledge. For me the built in sensor and read out is only relied on as a relative indication of where the individual grates might be. I use a Thermoworks Chefalarm's air probe on the grate with the most important piece of meat (if there is more than one being smoked) and set the MES to get the temp at the meat to where I want to cook.I usually cook on the third grate from the top (MES 40 Gen 2.5) and on the back side of the meat it can be 10-15 degrees less than the sensor and between the meat and the glass door 20-25 degrees.

Your experimentation and analysis is what I once wished I could have done.  But, now I like worrying only about the temp at the meat and set the MES to whatever it needs to be to get the meat location like I want it. Thanks again for the testing effort and especially the extreme effort to write it up.


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