Auber Temp Probe vs ET732 Temp Probe Difference

[jcrouse]

I am doing a dry run on a Weber 22" kettle with an Auber Temp Control and a SnS. Testing at a target of 225. It took me about 30 minutes to get the temp down to 225. It has been going for 4 1/2 hours since then with VERY little variance, maybe 2 degrees at the most on the Auber probe. The issue is that the ET732 is reading anywhere from 8 to 14 degrees less than the Auber probe, even though they are right beside each other and equal distance from the heat source. The ET732 has been ranging from 216 to 210 for the entire duration. I am testing the run for longevity at the moment and don't want to tear down the setup. When it is complete I plan on testing in boiling water. Does anyone have any thoughts or other suggestions?

Thx in advance,
John

[Jerod Broussard]

I got you in the PM. With my first probe I just recognized what the discrepancy was, and adjusted my Auber accordingly.

Right now, the probe I have is dead-on.

[Breadhead]

I have the same problem with the Pit Probes when I use both my DigiQ Dx2 and my Maverick ET 735. Like you I attach them side by side on the grate. There can be a 15° temp difference at the start of the cook but eventually they match within 1° to 2°. I've tested both in boiling water and their both accurate. I'm perplexed why that happens.

[jcrouse]

@ wartface. Yeah, my difference started out at 15 also. After almost 5 hours it is now down to 4 degrees. Very weird.@

[Jerod Broussard]

My Auber probes pick up on temp changes waaaaaaaay faster than the Maverick probes.

[Huskee]

If it's any consolation, sometimes a couple of my Maverick probes are WAYYYYY off at the start of a cook. For instance, yesterday morning when it was dreary and probably 62* outside, I had 2 Maverick probes that wanted to read 168* (or so) out in open air.

Then I pulled out & reinserted, and they read 170* and 208* (or so), it was weird. I put them in my oven in case humidity had affected the wire/probe joint. Eventually (20 minutes maybe) at 300* in my oven they read 297 and 299 respectively.

Then all was well.

But, I would HIGHLY suggest you Google your elevation's boiling point (212 is only at sea level) and do the boiling water test. I did, and I put a small piece of tape on each probe wire, at the plug end, showing whether they were off by 2 or 4 degrees so there's no guessing in the future. (A couple were dead on, but a few were 2-4 degrees off).

Moral: I think the probes are definitely the weak point, but they seem to, once at cooking temps, readjust themselves somehow- whether due to humidity evaporating or just the magical BBQ fairies waking up and blessing the whole operation. Not sure.

[jcrouse]

Well, I did a boiling water test and all three probes, food and bbq (from the ET 732) and the probe from the Auber were all within 2 degrees of each other.

Decided to try searing my first steak on the SnS. Picked up a 2" thick ribeye. While the grill was coming up to temp there was a 40 degree temp between the probes. I had the ET732 food probe laying on the grill beside the ET732 bbq probe and the Auber probe. I think the Auber hit 250, one 732 was at 230 and the other at 210, all while they were literally a 1/2 apart in the cooking zone. This is extremely frustrating and should not happen with an $ 80 grill probe (or whatever the ET732 cost) and a $150 thermo control, not IMHO. I can see maybe less that 5 degrees, but 40. It is simply not possible to use the grill like that.

Any more ideas?

Thanks,
John

[Doc Hazard]

Most temperature probes, and certainly the ET732, use thermal resistors as the sensor. This is a little glob of stuff (technical term) whose electrical resistance changes with temperature, usually exponentially. It's easy and cheap to make and to measure resistance, and then you just need a table to convert the resistance to temperature; but the sensor globs can and do vary quite a bit in their responses depending on mixture, size, and how the wires are attached, and with the history of their use and abuse. Plus, any other, possibly changing, resistance in the circuit, connections, plug, etc. change the reading. The probes are not a primary standard based on fixed physical principles, like boiling water. Thus the variations.

Those who measure temperatures that really matter use thermocouples: two different metal alloy wires are spot welded together at one point, called a thermocouple (TC). The junction actually generates a voltage based on the temperature. The temperature-voltage relationship is always the same for the same metal pair. The voltage is small, millivolts, and thus takes more electronics and $$ to measure and translate into temperature. But unless the junction breaks, it is always accurate; the TC is a primary standard as the output is based directly on physics. Thermoworks sells thermocouple probes; I'm not sure if their DOT probes or thermopen are TCs, likely because they are so thin: TC wire and junctions can be like spider web but still have the same V-T values. That's how they get the fast response: low thermal mass. You can ask them about those, and they sell other units that are definitely TCs. If you really care, that is the way to go. Lesson over.