Temp problem

[jimr]

I've built an electric smoker that is 3'x3'x5.5' which totals out at 50 cubic feet of space to heat. It is 2x6 frame w/6" batt insulation. I have a PID controller w/25a SSR and 2 1000 watt "hot-plate" type Procter Silex heaters. I test ran it tonight and in 2 hours got it to 180 degrees. It plateaued there and would not budge. The burners are $9.00 specials from Menards. I thought the length of time it was operating the temp should have gotten a lot higher than that. Is it underpowered with the 2 1000 watt burners? Would two 1000 watt strip heaters be better or wouldn't it make a differance. I calculated the two 1000 watt heaters use 16.66 amps, so I could go to a pair of 1250 watt strips and still use my 25 amp SSR. Any other ideas out there?? Any help here would be greatly appreciated

 

[pit 4 brains]

What are the burnes plugged into? Are you running an extension cord or using non-solid wire to power the burners? Just a thought....

 

[jimr]

Burners are plugged into #12 strand with an 8-10 foot 12/3 cord.

 

[tjc]

The hotplates probably have a built in thermostat and are kicking off when they reach that temp. You should be able to open them up and bypass the thermostats.

 

[bbally]

2000 watts should make it an oven.....

What kind of insulation is on this unit?

Some of the cheaper hot plates have a thermal switch in them. This limits the heat they can create in a confined space. Might put a current meter on the extension cord and see that they are staying on. Sounds to me like they are shutting down with a thermal protection switch.

If they are drawing current the whole time, then place a fire proof blanket over the unit and see if it is heat loss causing the problem.

 

[tjohnson]

I just tore apart my hotplate to see how the low-med-hi switch worked. It a little bimetal switch and will shut off when the temp at the element gets hot enough to trip the switch.

Either bypass the switch or put in different heaters without a built-in temp controls.

2000 watts is HUGE Power for your box.



Todd

 

[jimr]

I eliminated the switch altogether and am trying it again......Hope I don't burn my garage down

 

[bbally]

You want to go to the plumbing heating supply and get an oven thermostat, you can wire the heating power into it and have hot plates respond to that thermostat.

 

[jimr]

I actually have a PID controller for the temp control.

 

[deltadude]

1000 watts is enough to heat your smoker to 300º at 40º outside ambient easily, especially if it is insulated. You only need about 1800 btus to achieve 300º in one hour for that space size. 1000 watts puts out 3400 BTUs.

If you have a meter that reads amps, I would check to see how many amps you are actually drawing, as bbally said there could be a limit switch, and you removed it so maybe now that will solve the problem.

There could be a problem with the element types, since yours is designed for hot plate which works based on conduction requiring direct contact to transfer heat, vs, convection which is designed to heat the air around it.
While many have used a hot plate for small applications and get ok results, you can buy the right kind of heat element for about $40.

 

[jimr]

I gave her another run last night with the switch eliminated altogether and it ran up to 205*............but it took 2 hours and it was in my garage which was 60* with no wind to effect it. Looks like I will be going with something different. What's the general consensus, finned strip, tube or any other ideas? If someone with these heaters would like to chime in that would be great.

 

[pops6927]

35,000 btu propane burner at Northern Tools


I can get my smokehouse up to 300°+ very quickly in our ultra frigid Texas outdoor temps in the 60's! That's 54 cubic foot too (3x3x6)!

 

[jimr]

Thanks, I've already got it set up for electric though. I've got an email into Tempco Electric Heater Corp for info on strip heaters.

 

[morkdach]

i just put a small perforated pan with about 6 brickets on the element and that should kick your temp up to where you want & still control with your PID

 

[deltadude]

I gave you a link to a standard convection type heat element. You will need a protective cover over the element to prevent grease from dripping on it.

There are several outlets for elements, you might call around and ask their opinion. There are more than one way to heat your application up with electric. The style of element I linked to above is pretty much the same as what is in the MES.

Personally I would try to achieve a temp of 350º so you can crisp up chicken skin. But you need to know if your smoker walls can handle that heat, and if the insulation won't cook at those temps too. (DO NOT FOLLOW THIS ADVISE! Self edited after research)

Also did you check the amp draw to determine the watt output?

 

[jimr]

Thanks Deltadude, I checked out the link you included in your prior post.

I am seriously considering 1 or 2 finned strip heaters from Grainger made by Tempco Electric Heater Corp. Do you think these heaters will work for my application?

My walls are made of 2x6 frame with 6" fiberglass batting covered with 1/4" plywood. Do you think this will stand up to 350*?

I don't have an amp meter to check the draw of the burners I now have, but will try and locate one.

 

[deltadude]

This is an error, I had a lapse and forgot you were doing this with plywood. Plywood is safe around 200º and maybe up to 250º. However without a specific MDS for your plywood it would be hard to put an exact safe max temp. The big consideration for me would be at what temp does the binding chemicals start releasing odors?

I will take a look at the Graingers elements and get back to you.

You could line your plywood smoker with Hardiboard, or maybe just the around the heat area as extra protection, similar to this plywood smoker.