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Thermometer Readings....Questions


 
Bruce Bissonnette

Bruce Bissonnette

TVWBB Guru
I have a Tel-Tru thermometer 2 1/2" stem mounted in the lid opposite the lid vent. I have checked the accuracy of this thermometer several times and in boiling water and ice water it is within 2º, so it's basically right on. If I insert a digital probe thermometer (which I have also tested and is accurate) in the lid vent I get readings that are anywhere from 20-35º different then the reading coming from the Tel-Tru.

For example, I cooked a brisket Friday night and the temps on my digital probe in the lid were pinned at 257-266 the entire cook while the Tel-Tru was registering between 225 -235.

Why? Any ideas, is it that the exhaust air is hotter than the air circulating near the Tel-Tru therm? That's the only thing I can figure out? Inquiring minds want to know.
 
I have encountered the exact same thing with my Tel-Tru, which as you say, is accurate, as well as my Thermapen. Even my cheapy wired probe therm that I've had for years is accurate within 6 degrees.

But all read a different temp when put thru the vent holes in the top. Now my Thermapen and wired probe are the same length, and the distal tip sits in the same place distance wise from the top of the lid. I know I have a thermocouple on the Thermapen that gets its reading right from the tip, the cheapy wired one, isnt a thermocouple I dont think, and it gets the temp a bit higher on the shaft.

With that said, my Tel-Tru always reads 25 degrees colder than my other two, that are usually within 4 degrees of each other. And my Tel-Tru is the same length within a few quarter inches as the other two.

Couldn't tell you why, but I share in your slight irritation.
 
Bruce

I have two holes drilled in my lid probably 1 1/2 " apart with a TelTru in one and a Nu-Temp dig in the other inserted exactly the same depth. The Nu-Temp is 20-30 degrees higher than the Tel-Tru after the temp gets around 250. Can't figure !!

JC
 
Ditto on the observation!!!


Originally posted by Bruce Bissonnette:
..... is it that the exhaust air is hotter than the air circulating near the Tel-Tru therm? That's the only thing I can figure out?....
Click to expand...


That's the conclusion I came to.

JimT
 
Same, same for me. I tend to see a 20 deg or so differential between Maverick ET73 pit probe and the tel-true through the vent, but all test out fine individually. With the Guru I don't see as great a spread in difference between it's pit probe and the maverick, only about 10 degrees.

I stopped fretting, since over time I've realized that none of this was actually affecting my cooks.
 
I have experienced this same problem for the last year and it always left me questioning where I was getting accurate/inaccurate temp readings. After e-mailing another member on the board who had experienced the same problems, mine is finally solved.
I had a 2.5" stem Teltru mounted on the opposite side of the lid from the vent, the same distance down from the handle as the center of the vent (3 3/4" I believe). Grate temps were always higher than lid temp and was way off when dropping a Maverick probe thru the top vent.
Last week, I did my first overnight cook since replacing the 2.5" stem Teltru with a 4" stem Teltru in the same location. The temps were within 5* between the Teltru and Maverick smoker probe dropped thru the top vent for more than 15 hours.
The only thought as to why the 2.5" stem doesn't work in that location is that possibly the draft pulling up thru the smoker and across to the vent in the other side of the lid creates some sort of void at that location.
 
Well, I'm glad to see I'm not the only one. And it's not really something I worry about, I've done enough cooks that if I can keep it the lid temp in the 240-260 range I'm a happy customer.

It's just something that has bothered me since I installed the Tel-Tru..one of those WHY things that's all. Where's my beer......
 
Originally posted by Brent Bristle:
I have experienced this same problem for the last year and it always left me questioning where I was getting accurate/inaccurate temp readings. After e-mailing another member on the board who had experienced the same problems, mine is finally solved.
I had a 2.5" stem Teltru mounted on the opposite side of the lid from the vent, the same distance down from the handle as the center of the vent (3 3/4" I believe). Grate temps were always higher than lid temp and was way off when dropping a Maverick probe thru the top vent.
Last week, I did my first overnight cook since replacing the 2.5" stem Teltru with a 4" stem Teltru in the same location. The temps were within 5* between the Teltru and Maverick smoker probe dropped thru the top vent for more than 15 hours.
The only thought as to why the 2.5" stem doesn't work in that location is that possibly the draft pulling up thru the smoker and across to the vent in the other side of the lid creates some sort of void at that location.
Click to expand...
Sounds plausible to me, I'm sure Weber's placement of the top vent is by design. I was reading on the Komodo Kamado stuff they moved the vent to off center to reduce hot/cold spots inside the cooker.
 
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