Temp Control Variance

DoubleEgger

This one is a new one for me. The last two cooks where I used the Stoker, I had some wild variances in the temp between the dome and the Stoker probe. I’m talking about 75+ degrees for the entire duration of brisket cooks. This is nothing like the typical variances between grid and dome temp. Most of the time it’s 25 degrees or less. Well I know what you’re thinking and I was thinking the same thing. Calibration. I calibrated 4 stoker probes and two thermometers. The probes were within a degree or two and the thermometers needed about 15 degrees adjustment. Nothing near a 75 degree swing. Put the Stoker on tonight for an overnight cook at I’m seeing about 85-90 degree variance tonight. I’ve got the stoker set at 200F. The probe is 216F and the thermometer 305F. 

This one has me stumped. 

alaskanassasin

Smobot is set at 225 pit 230 dome 230 

DoubleEgger

We’ll see what it looks like in the morning. Might be having pork for breakfast. 

caliking

Have you checked if you get the same temp variance with each probe?

Also, clip a probe to the thermo stem and see what temps you get. 

Either the probes are bad, unit is bad, or something shields the probe when clipped to the grid.

mahenryak

I wonder how the temps would compare if you were to clip the pit probe to the dome temp for a few minutes with the blower off?  

Edit: Looks like caliking had the same idea...

GoooDawgs

Is there a lot of meat in there?  I've had 75 degree variance between grid and dome when it's loaded on 2 levels.    Usually after 5 or so hours it all evens out - but it's definitely a stressful time! 

bgebrent

Curious problem.  Calibration and all accounted for.  It’s the equipment.

DoubleEgger

Was running 200F on the controller and 275F dome this morning. 10lb butt is 160F after 9.5 hours. 275F has got to be closer to the actual temp. @caliking I have two sets of probes. I used the other set this go around. Clipping the probe to the thermometer is a good idea. I’ll mess it after the cook. 

ryantt

@DoubleEgger let us know what you figure out.  This questions was asked yesterday in a Facebook group, almost identical situation except it was with a different controller.   

stlcharcoal

Is the dome temp probe hitting the meat?  I've had that happen before.

I've also had the fire burn on one side of the firebox......so the temp has a 50F+ swing than the other side.  Open it up and just swap the temp probe to another spot and see if you see an immediate rise in temp.

DoubleEgger

stlcharcoal said:

Is the dome temp probe hitting the meat?  I've had that happen before.

I've also had the fire burn on one side of the firebox......so the temp has a 50F+ swing than the other side.  Open it up and just swap the temp probe to another spot and see if you see an immediate rise in temp.

Nope and already did that.... 

Canugghead

Check the pit probe's CAL (calibration) value, is it 0?

Coincidentally, few cooks ago I noticed my Stoker pit probe had a variance from dome therm. I didn't bother doing the boiling water test etc. (lazy), once the egg was stabilised, I tweaked and set the CAL value to -15 to minimise the discrepancy 

DoubleEgger

Canugghead said:

Check the pit probe's CAL (calibration) value, is it 0?

Coincidentally, few cooks ago I noticed my Stoker pit probe had a variance from dome therm. I didn't bother doing the boiling water test etc. (lazy), once the egg was stabilised, I tweaked and set the CAL value to -15 to minimise the discrepancy 

The probes have been adjusted. They passed the boil test. 

mahenryak

So, I guess what I'm wondering is what your cooks seem to be telling you?  Do they seem to be finishing faster than what the grate temps would seem to indicate, more in line with what the dome temp is reading, or not?  The answer to this question is probably the most important in terms of planning your cooks, right?

mahenryak

It's been a while, @DoubleEgger and I don't know if you ever solved the mystery but here are a few photos representative of my cook today using the Stoker pit probe connected to my dome thermometer.  Please, ignore my dusty egg and upside down thermometer (can't turn it once probe is clipped, and I'm not very bright).  The bottom line is the temps agree fairly well.

DoubleEgger

Thanks for following up. I never came up with a conclusive answer (haven’t messed with it). My gut is telling me that it’s due to two things. The temp probe ended up in a cold spot and the dome thermo overshot due to the change in airflow due to the platesetter. I’m going to put the platesetter in next time with a leg protecting the dome thermometer and see if I can minimize the variance. 

mahenryak

No problem.  You're welcome.  

lousubcap

@mahenryak another thank you for the follow-up.  The great majority of "I have a question/help" posts result in genuine options as solutions.  Yet, less than ten percent of the OP's ever provide what option they went with and how it turned out. Feedback is a key component in improvement.  Off soap-box. 

mahenryak

You're welcome, and thank you for the kudos @lousubcap .  I know we all get busy, too.