Thermometer Probe Problem

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Fire Starter
Original poster
Nov 18, 2010
I have two thermometers; a cheap walmart one and a Oregon Scientific AW131.  Both have been checked using the ice method and boiling water and both read correct.  The problem comes when I insert the Oregon one into a potato and get reading in my smoker 40 degrees higher than the walmart one and oven thermometers as well.  I will place the cheap walmart and oven in the same spot and get reading of 225 but when the Oregon is placed it will read 265.  Whats curious is that sometimes in will read correctly after about 4 hours.  Would the potato be throwing the readings off?  Any and all advice would be greatly appreciated.
That is strange...two probes acting completely different...are the probes configured the same way (one straight, one with a bend)?

I've never used the potatoe method myself, but opt for just a small piece of wood with a hole drilled just large enough to fit the probe. It is possible that moisture and the additional mass of the potatoe could somehow throw th ereading off kilter.

I'm wondering if there could be moisture from the potatoe getting into the probe where the cable runs inside the tube, though this would be unlikely in a hot smoker. They can be very susceptable to problems if water gets inside the tube, and can eventually short-out and not work at all.

Not trying to be a smart a** but are you getting the probe through the potato far enough that you are getting a proper reading? Another thought is to run the probe through the top vent and just kind of suspend it right above the grate and see what kind of readings you get
The cheap walmart one has a bend at the end 90 degree angle.  The Oregon is straight.  I put the probe all the way to the end of thermometer in the potato.
Did you put them both in the potatoes? Were the ends exposed the same amount? I would do like piney says & drop them both thru the top vent & see if they read the same.
I have had issues with my meat probes not reading the correct temp as well some times when I am using a meat probe to measure the air temp. I always though it was because they were really meant for probing into meat and they were getting a funky reading because I was trying to read air temp. I will have my E7-73 going in my smoker and I will put the smoker probe and the meat probe (through a small piece of wood) side by side and they will read 40 degrees off and I know the smoker probe is the accurate one because it is reading the same temp as my analog thermometers that are in the side of the smoker. Normally they will even out and read the same eventually but it is annoying when they are different. Good thing I have the analog ones in the side so I can compare the three and figure out which is correct and like I said it's usually the smoker probe that is right on.
On my last smoke this is what has worked for me (picture).  The temps are now within 5 degrees of the oven thermometers.  The only thing I find curious is the cheap thermometer can read the temps variations more quickly.

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