Analog vrs digital temp gauges ?

[Smokin Okie]

I put a brisket on the Brazos at 5 am this morning. Its now 6:23 am. You will see in this pic , my analog gauges reading from 275 lower left to 285 or so on the right and one in the lid is about 285. I got no problem with those differences.

But I'm gonna add a pic of my Thermoworks digital temp, with the probe on the cooking grate that is not 2 inches away from the Tel Tru on the lower left.

This is not an isolated occurence. Its every cook. I gotta think the three analog gauges telling me I'm cooking around 280, are correct. And I've tested the gauges and the probes in boiling water. Its a mystery to me.

 

[daveomak]

So the thermoworks reads 341F....

There is laminar air flow inside a smoker... colder near the skin... warmer in the center..
That's routine...
Use the gauges as a guide...

 

[Smokin Okie]

I'm three hours into the cook, deep into the stall. I opened it up to look at it for the first time. And I moved the digital probe a couple of inches. Its now within 5 degrees of the Tel Tru.

Before I lifted the lid, the digital was reading 40* higher than the Tel Tru.

Thats amazing. But I feel better about my cook. I've been cooking by the Tel Tru.

 

[daveomak]

So... now you know add ~40F to the tell tru therms...

 

[Smokin Okie]

Well, I'm still not sure.

If all three analog gauges are pretty much in agreement. And the digital is reading 40* hotter. Then I move the digital a small amount and it agrees with the analogs .......... then it must've been the placement of the digital.

That's all I can figure. IDK what causes this.

All I did to the digital, was move it over one " hole " in the expanded metal grate. I have a clip that holds the probe. I just moved the clip one hole and amazing diff.

All that said, I just smoked an 8.5 # brisket in a little over 5 hours. That bothers me a lot . Makes me wonder what my cook temp really was.

 

[Smokin Okie]

Any advantage to a 4" stem on a Tel-Tru, as opposed to the 2.5" stem ?

 

[daveomak]

There is laminar air flow inside a smoker... colder near the skin... warmer in the center..
That's routine...
Use the gauges as a guide...

 

[JWFokker]

Where is the probe in the cooker? You may have found a hotspot. The cooker itself will conduct a fair amount of heat near the firebox.

 

[Smokin Okie]

Where is the probe in the cooker? You may have found a hotspot. The cooker itself will conduct a fair amount of heat near the firebox.

The digital probe was right next to the Tel Tru on the lower left in the pic above. I place it as close as I can get to that Tel Tru, cuz I use that Tel Tru to cook.

I only put the digital probe in the cooker so I can use Thermoworks Gateway to create a chart of my cooking temps. I had a pork butt cook a couple weeks ago and the digital and Tel Tru ran pretty close together, even though at the start of the cook I had placed one of the butts too close to the 4" stem on the Tel Tru. Once i adjusted the butts , the digital and analog pretty much agreed.

On this cook, I had put a 2.5" Tel Tru in that lower left spot, to avoid getting it too close to the brisket. I'm going back to 4" .