temp control is worthless

[plj]

I've been having some trouble regulating the temp in my new (xmas) electric smoker. OK, a lot of trouble. So I decided to do some tests today - namely, I measured the internal temp (with 2 different thermometers) over the range of possible settings. My temp control goes from 60 to 250:



Results are terrible! The lowest temp I could achieve was 140 degrees! The temp never got clos to what the control dial said until I was up around 225. Even then, at 225-250, the internal temp varies by as much as 30 degrees. Yes, I "wrote down" all the numbers in excel because I have a terrible memory. So just to prove that I really did this, heres a q-view graph of the setting on the dial and the internal temp readings from the 2 thermometers:



So what should I do? Try to return the smoker? Based on everything I've read here and elsewhere, I probably wont do much better with a different unit. I dont know, maybe I'll just be mad and build a good temp controller for it. It ticks me off that they put such a piece of crap controller in these electric units - for crying out loud, the reason I bought an electric is so I can do lower temp smoking, and because I've proven I'm not good at controlling the temp with gas or charcoal! Then they go and put in cheap parts that dont control the temp!!!

 

[rivet]

Hmm.

Offset charcoal smoker?

Okay...'nuff fun. Serious now:

The differential from your in-place dial and your "Standard" thermometers is great until about 220F.

Did you calibrate your standard thermometers? If not then, then you should, and re-plot.

(assuming a stock-thermo is not calibrated nor works very well. If possible, calibrate that one too.Then re-plot as well)

After 220 F your Taylor reads about 8-10 degrees hotter than the stock dial, then dives after a given time which you do not show on your graph. No worries.

At this point we know that the Taylor matches your stocker dial from about 220 F to about 250 F.


Your probe is pretty much dead-nuts on to the Taylor all the way from 140 F to 260 F where it diverges hot for what looks like 20 degrees.

Important note- at this point we don't know which one is correct, none have been calibrated- that's why it is important.

After the probe takes off to and peaks at 280 F it comes back down to pretty much mirror the Taylor unit.

At this point, this indicates that the probe and the Taylor are most probably correct and certainly more reliable than the stock unit dial if both were used "out-of-the-box".

A concern would be the Stock Dial unit, pegging out and holding at 250F. Not good when you have 2 others showing variation.

If you look at your chart, the stock reference points show "steps" or are "clunky" as compared to a more realistic temperature fluctuation reading from the other two thermometers as the temps increase. Red flag there....your stock temp controller is unable to accurately maintain or reflect actual temperature differentials across time. In other words, it doesn't work.

But you already know that.

Since the other two - with one exception point- mirror eachother, the indicators are that they work and fairly well. (What are the odds of two separate thermometers NOT WORKING IN IDENTICAL FASHION?)

So what does this mean?

Your temperature controller is bad, as is it's internal thermometer. The rest of the unit should have no problem unless there is obvious damage to its integrity.

Good job on the excel plotting, it did you good. Points for that alone, my friend.

Hang in there, it's all part of the fun of smoking.

May the TBS follow you wherever you go.

 

[plj]

Thanks for the comments Rivet. I've found links to a PID control that I can build for $75-100, I'll probably do that. Ticks me off though, I shouldnt have to spend that $.

No, I didnt calibrate my thermometers. Agreed, need to do that, thanks for the push. Will do it on all of them today.

One thing I didnt mention though, I was moving things around so I didnt expect the 2 thermometers to be identical - I had one near the back, one near the front, move one to the center, one higher up than the other, one right next to the smoker's thermostat bulb... Me being me, I was trying to do 3 things at once.

I was also moving my drip pan up and down to see what effect that had, thats why I have multiple measurements at each temp setting.

 

[plj]

While testing temps I also observed significant variations based on where I put the thermometer - up high was hotter, in the back was hotter, right above the heating element was hotter (!) . Right in the center - exactly where the meat goes - is the coldest spot. Figures, doesnt it.
My drip pan is very large, its basically the full size of the inside of the smoker with just a 1" gap at the back of the smoker and a 1/2" gap at the front.

Question: Would I get a more even heat distribution if I used a rack with a smaller drip pan positioned right under the meat?
edit: Now that I've said it out loud, I think the answer is probably obvious. I'll just try it.

 

[bbq engineer]

PLJ,

I'm sure it isn't just me, but I have an internal drive to find the root cause of "why" things don't work properly. Then I can usually fix them...I would have that baby torn apart on my work bench in about 2 seconds flat, but first you will need to run additional tests to isolate the problem.

I don't have a Cabelas Smokehouse, nor am I familiar with them, but I do have a couple of observations and suggestions...

I noticed that the control dial is just that, a dial. You will never get the accuracy out of that to set a specific temperature, and they will never be as accurate as a digital setting. It is more of a "ballpark" in terms of accuracy. If the difference of setpoint versus actual were plotted and it were say 50° off in a linear fashion throughout the range, you would need to adjust your dial.

The placement of your thermos are critical to your test...did you place them at the same location as the thermocouple for the Cabelas smokehouse? If not, they could read completely different. You need to standardize their placement to ensure valid results.

Test thermos need to be calibrated.

If you have drip shields or water pans with your unit, you should have them installed also. For instance, I have a home-made vertical insulated smoker that I fire with charcoal, with a water pan that isolates the smoking chamber from the firebox. The purpose of the water pan is two fold...act as a heat sink so the temp is stabilized and add moisture to the cooking environment (which is debatable as to if this does anything). Without the water pan, my temps will spike tremendously. If you have a heating element sepatated by a shield or a water pan, the thermocouple will read way different than if you have direct heat blasting the sensor.

I have considered making my own BBQ guru out of a PID sensor, thermocouple, and fan unit. It would be really easy to do, but I haven't gotten around to that project yet. If it comes down to redesigning the unit to make it work properly, I would probably take it back and see how good Cabelas customer service really is...Then go with Rivet's suggestion of a charcoal or wood smoker!

Good luck.

 

[erain]

before i would tear it apart, i would call cabelas and talk to one of there product spe******ts, first i would double ck the thermos you used in the test to be sure data is accurate. they have a great customer support team and i have never had them fail me on any issue.

that said i think most of us pretty much know the stock analog thermos and controls are something we really do not rely on. which is why a digital single or dual probe thermo is key to great smoking success and consistancy.

 

[plj]

Calibrated thermometers in boiling water today. (just a "light boil", not rolling).
My single probe maverick (the one I used in the tests) said 204.
The probes on my dual probe said 203 and 205.
Candy thermometer said 204.
I didnt put my dial (oven)thermometer in the water, didnt know if that would ruin it. :)
Webers boiling point calculator says it should boil at 210.

So I'd say my probes average a few degrees low, but are close and consistent. Heck, when we were kids we used to cook meat and eggs on hot rocks in the campfire, I'm guessing the internal temps were off by more than a couple degrees!

 

[plj]

Yes, I agree cabelas support is pretty helpful. The problem is that I dont expect them to be able to get me a good control, just like you said. I could go through 10 units and not get one thats any better. So at the moment I'm still conflicted, I figure its either dont have an electric smoker, or "if you want it done right, do it yourself."

 

[plj]

btw, I appreciate your thoughts & comments, thanks.

 

[smokeys my pet]

Pretty much NEVER believe the factory installed!!! Trust the ones that you did in the boiling H2O. That is the safest!!!!!!!!

 

[sixpack]

plj...have you looked at these plug and play pid units.
http://auberins.com/index.php?main_p...products_id=72

 

[plj]

Yes, I found the auberins site. Lots of good stuff there, I'll probably end up doing the "build it yourself" version, save some $. Thank you.

 

[scubadoo97]

ya beat me to it. Auber has a lot of great plug and play products. Although not cheap they are better priced than many PID products

 

[builder59]

plj,

I have the Auberin controller for the Bradley for a unit I made from scratch. That thing is incredible to say the least. I have a Maverick a Polder thermometer and they are all within two degrees. The thing about the PID is that it is extremely easy to use and it is so damn accurate it is not funny. If you want your smoker set to 154 it will get to that and stay within 1 degree. I need to post the final results of "the start of a fridge conversion" A standard build it yourself pid is a hassle to program, his made for the bradley is a breeze. I walked my teenage daughter through it once on the phone.

Good luck,

Ron

 

[geek with fire]

Temperature control has been a pet project of mine for a few years now. I use custom controllers on my chargriller and sometimes my drum. Some things to keep in mind: Any automated temperature control is only as good as your sealed intake. If you shut everything down and your temps don't drop, no temperature controller in the world is going regulate it for you.

Second, a PID controler is only as good as it can be tuned for your specific cooker. If I use the same proportional integral derivative ratios for my drum as I do for my horizontal, the temps will see-saw and ramp up to a flaming inferno. So, whatever controller you use, make sure it's tunable; auto tuning is even better.