this post was submitted on 21 Feb 2025
226 points (96.7% liked)

hmmm

5401 readers
3 users here now

For things that are "hmmm".

Rule 1: All post titles except for meta posts should be just plain "hmmm" and nothing else, no emotes, no capitalisation, no extending it to "hmmmm" etc.

founded 2 years ago
MODERATORS
 
top 18 comments
sorted by: hot top controversial new old
[–] [email protected] 58 points 3 weeks ago (3 children)

IR thermometers aren't particularly accurate. Especially when pointed at reflective surfaces like glass, where some of the return will actually be reflected heat coming from you.

Most wall thermostats are designed to read the temperature of the air; the wall behind may be warmer or colder.

[–] [email protected] 8 points 3 weeks ago (1 children)

This is why it's important to get one with an adjustable emissivity, so you can adjust it to whatever material you are measuring. Or you can stick some electrical tape on what you want to measure, 3M super 88 is 0.96 so I just set my fluke to 0.96 and stick that shit everywhere I want to measure.

[–] [email protected] 3 points 3 weeks ago

But 88 is trash my dude
I'm a 33 man

[–] [email protected] 7 points 3 weeks ago (1 children)

Most wall thermostats are designed to read the temperature of the air; the wall behind may be warmer or colder.

This is correct. Specifically for the honeywells, they have little holes to measure air temperature usually on the top or bottom depending on model. The smart ones (like this one is) can also be manually calibrated up or down from what their internal thermostat says if there's a known deviation (i.e. the wall is consistently putting off enough heat to throw off the stat).

[–] [email protected] 1 points 3 weeks ago

Also the electronics in the thermostat might be generating juuuust enough heat to make a difference depending on where the IR thermometer is pointing

[–] [email protected] 24 points 3 weeks ago

A man with one clock knows what time it is with certainty. A man with two clocks is never sure

[–] [email protected] 12 points 3 weeks ago (1 children)

Only 1.6° difference that's probably within tolerance especially when it's not calibrated after leaving the factory.

[–] [email protected] 9 points 3 weeks ago (1 children)

Yeah I have one of these infrared thermometers. The tolerance is within 1°C. They aren't designed for precision but for "is this thing at a temperature that I expect".

[–] [email protected] 2 points 3 weeks ago

That's assuming you've got the emissivity set correctly, too. Can make a huge difference

[–] [email protected] 11 points 3 weeks ago

Woah you mean every thermometer isn't perfectly accurate??

[–] [email protected] 8 points 3 weeks ago

It knows something, interrogate the thermostat.

[–] [email protected] 6 points 3 weeks ago

Thermostat is displaying bullshit? Always has been.

[–] [email protected] 6 points 3 weeks ago (1 children)

Point it at the wall right next to it and see. I've noticed this on mine but it will match with the wall. The reflective comment could be. I've always assumed that it has to account for the slight heat that the thermostat generated just by running. My experience is with an ecobee smart thermostat so probably generate a a bit more heat.

[–] [email protected] 1 points 3 weeks ago

I have an IR camera adapter and pointed it at a computer fan. I was astonished that the motor in the middle was warmer than the blades, although the fan was off for a long time. Then I saw that it measured the reflection of my head in the name plate.

[–] [email protected] 3 points 3 weeks ago

The thermostat reads the temp in its immediate area, and many times it’s mounted on the wall where the heating or cooling vent is located. This is why your thermostat reads one temperature but your room across the apartment feels colder.

[–] [email protected] 3 points 3 weeks ago