Question for Temp / Humidity Sensors regarding Offset Settings

So I'm curious... I've just started working with smart home sensors such as the temp / humidity sensors. One thing I noticed is many of them have "offset" settings to adjust say the temp and humidity. I'm curious what people are using to take accurate measurments to determine if an offset is necessary for the sensor? Thanks!

I purchased a calibrated standalone temp and humidity meter. Having spent a pile of time a few years ago calibrating temps to use for a vent control app i was writing, I came to the conclusion that it wasn't worth the effort...

ok, one of the reasons I'm asking is mostly for the humidity offset. First, my main bath in my house is relatively small, and the humidity in the bathroom is currently showing 72 and there is literally no door on the room because I am remodeling my house. No one has been in the shower since this morning. I am getting readings from my Aeotech Multisensor 6 on USB power. I added a Zooz 4-in-1 sensor to my bedroom and it's getting a humidity reading of 67.85. It's the room right next to the main bathroom. There is however a fair amount of A/C being pumped into the main bath vs the bedroom. The other reason I ask this question is because monitoring humidity for me is a real concern. I plan to have a 125 gallon saltwater aquarium in my living room with a dedicated filtration room in my basement where I'll have a ceiling fan to draw moisture to the outside when it gets too high. My concern is with too high humidity I don't want to start having mold issues but was curious how "accurate" my sensors really were.

This is the one I purchased.

Thank you!

I too did a lot of research into this area years ago when I had to have relatively precise control of humidity for the print technology I used to work with. You're going to find that any hygrometer you purchase will have a deltaE of +/- 2% to 4% RH on average. The difference between 72% and 68% is most certainly not mold.

Having said that, if you live in a cold climate, you do need to be concerned about mold in the walls if your indoor humidity is too high. But as far as accuracy goes, take the closest two and then make them the same. Adjust everything else to that value if you like, but understand that they may track differently. You'll get them set the same at say 60% RH, but then at 40% or 75% RH reading on one, may not read the same on the other. At least that was my experience with many types over the years, from cheap to very expensive.

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I've not tried it recently but there is a strong relationship between a saturated salt solution and RH

I used to be obsessed with "absolute" accuracy only to finally realize that it didn't matter for the things I was measuring. Now I'm more concerned about repeatability.

Remember the old adage:

A man with one thermometer knows what temperature it is, a man with two thermometers does not know what temperature it is.

Probably should change it to gender neutral but this is how I first read it.

I purchased 9 or 10 Aeotec multisensors. Before installation, i set them all up together out of direct sunlight and any heat vents or doors etc. I then setup all devices on a config dashboard screen and let all sensors stabilize. I then averaged or chose the majority of closest temps or humidity and offset the requires ones so they all matched. Tested a second and third time until happy. Then installed!
Was quite easy and ensured all are set similar.

Don't ask me what I will do when I purchase more?!?!?!

Thanks i thought about doing this as well. I have one already in place but easy enough to pull it out temporarily to do just this. Thanks!

I did what @mike.maxwell did, but with a different brand. An NIST calibrated digital thermometer/hygrometer is pricey compared to one thatโ€™s not calibrated, but to me it was worth it.

Which one did you choose? Thank you.

Thanks! Thatโ€™s cheaper then the other one too!

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