Axiom Home Page Forums General Discussion The Water Cooler Question for the BBQ experts

I decided to stick with boring and put in in my smoker.

I've been meaning to pick up a secondary digital thermometer for a while now just to verify what temp. my smoker is really running at. I had read on several bbq forums that the manufacturer supplied thermometers could be out by varying amounts.

To check that I picked up a Thermoworks DOT. It seems to have a good rep for reliability and accuracy. I checked last night and my DOT shows 109 at the boiling point, so it reads 3 degrees low.

I'm happy to say that the thermometer in my smoker is quite accurate. In fact, a little closer to true temp than my DOT. I set the meat probe on the grill and watched the two during the smokers start up. The GMG temp. consistently showed 2 degrees warmer than my DOT, so it is only 1 degree out from true temp. If you actually adjust for altitude (1000 ft.) its bang on!

So, what's going on in the GMG is interesting and suggests some clever engineering. The temperatures reported by the cooking chamber probe range quite a bit more than the air temperature at the grill.

I did my test at a 195 F set temperature. The outside air was at 52 F (damned tropical for this time of year!!)

The Chamber probe ranged as much as 50 degrees between cycles while the max air temp swing was 20 degrees with most cycles varying around 7 degrees.

One thing the geek in me noticed is that there were temperature swings even when the grill was not feeding pellets and the largest temperature swing was during a pellet feed cycle.

[FullGeekOn]
I have been wondering how they figure out the proper feed rates for pellets given that you could be running this grill in anything from sub zero to very hot days. My guess is that they do that by monitoring the chamber probe as they vary fan cycles. As long as there are pellets in the chamber they use changes in fan speed to bring the temperature back up when it falls below a certain level.

If that does not work and the temp keeps dropping, the auger starts feeding pellets and the fan kicks up a notch or two until the temperature starts to rise.

It is during the pellet feed cycles that the larger swings happen.

I'm guessing you could actually infer outside temperature (80F vs -15 F) by the rate of change at the chamber probe during heating cycles and vary your feed rate. I don't know if that would actually be needed though.
[/GeekOff]

Long story short, it appears that the temperature variation is actually much less than I thought with a max swing of 20 F during only some of the heating cycles and most swings below 10 F.