Making sense of home humidity sensors

panvulcon

Hi, I have a couple of expensive air vents in my basement which help keep the humidity in check. They display both relative humidity and absolute humidity however, the relative humidity / absolute humidity seem to be conflicting. 

I’ve used an online humidity conversion calculator to check the results and either my vents are not reading correctly or I’m calculating it all wrong (which is entirely possible). Before I reach out to the company I purchased them from I’m keen to get some feedback from the forum to see if you get the same results.

Here’s a link to the online humidity calculator - https://planetcalc.com/2167/

Vent 1)

Vent 2)

panvulcon

…the calculator uses kg/m3 not g/m3 

neilmcl

I assume you know the difference between relative and absolute humidity?

Where are the vents situated and why is one able to read the outside air temperature whereas the other one isn't?

panvulcon

Sure, RH is how much water can be absorbed in air at a given temperature and air pressure, which is why the relative and absolute humidity don’t look right to me. 

…one vent is drawing air in whilst the other is pushing air out. 

theoretica

Are those recent data from the vents?  External air 0 degrees C isn't what I would expect at the moment.

panvulcon

Hi, yes that particular vent is output only. The other vent is bidirectional.

neilmcl

Surely the relative humidity on the second sensor is going to be influenced by the incoming air temperature that it's drawing in, hence the difference.