My Gutted MES40 Temperature Statistics

[rick123]

Awhile back I gutted the inside of my gen 2.5 MES40 removing everything and then flipping the heating element to center it in the smoker. (original post here: https://www.smokingmeatforums.com/t...s40-another-possible-mod.242544/#post-1728029)

I am now working on a a new project for this; an IoT PID. As part of my testing of my thermocouple probes and sending data to my webservices, I decided to run a full 1 hour temperature check across the smoker.

First, the setup:

1. Smoker in the garage so no wind. Ambient temperature of 70 in the garage today.
2. Three thermocouple probes in the smoker. Middle one is on an alligator clip connected to the center rack. Other two are meat probes so they are held by foil. All of these are highly accurate and calibrated within .75 degree accuracy.
3. Smoker vent on the 2.5 is located on the top left back corner. Vent is wide open.
4. Mailbox mod is attached with door closed. No smoke and nothing burning in the AMNPS. (Might run again with smoke but don't expect that to change anything.)
5. Smoker is empty except for racks and bottom drip pan.
6. Smoker temp is set for 250.

Observations:

1. As I already knew, the built in temp control is off. I used to think it was reading about 10 degrees too high but now I see it's about 20. Won't matter once I get my new controller finished :).
2. Like others have notice, when heating up you get an early temperature spike. It appears to level off fully about 30 minutes in but I'm sure ambient temperature and wind would effect this.
3. I know others have tested the temperatures across various parts of their smoker and this I think is clear now that gutting this thing and centering the element helps keep those temps closer across the entire unit. At the 46 minute mark you can see the bottom right was 227, middle was 224, and top was 221.

 

[dr k]

I did what you did but with my drio pan disposable 11x15 alum baking sheet on the bottom rack. With no food I could slide the baking sheet a full or half rung left or right to get left and right temps the same across my go to 2nd from top rack. Which was a couple degrees cooler than the 2nd from bottom rack and the hottest was the top rack below the top right rear vent on the gen 1 40. Then with a pork butt on 2nd from top rack absorbing heat and being an upper obstacle I'd hit 275 in an hour and after the auber PID started cycling and, holding within a couple degrees the whole smoker was pretty even, having heat to go around the drip pan up the walls and back to the center. I still have probes on the left and right of my food at rack level instead of higher or lower than food. If sensors are higher than food the bottom of the food is hotter than above from the food absorbing heat and I don't want to burn it on the bottom. Different PID have settings not comparable to others so sharing settings is only with Auber brand I'm familiar with. I do the P mode with P=1, I=0 and D=0. It's full output to get to one degree below set point then at 1/2 degree below set point it flashes for 50% output and off at set point. So I'm 100%, 50% or off with mailbox mod and top vent wide open. Tis will over shoot 10 degrees when preheating but not with a load at 275. It seems the vent side is hotter and heat coming around all side of the drip pan wrap to the center and toward the top and cascades down around food and ultimately to the top vent with watching the smoke turbulence with the drip pan and meat load.