Recommendations for humidity sensor (for bath fan)

I’m in the market for a reliable, semi-accurate humidity sensor to automate a bath fan (in the US). I’ve searched and while there are several threads about this, most of the devices are no longer available (including the Everspring and the Centralite ones). Does anyone have any others to recommend? Or know where to find those?

Being able to permanently power it would be ideal as well, though not a deal breaker. On that end, does anyone successfully use rechargeable CR2 batteries? My recessed door sensors eat them.

Anyone have experience with the Aeotec Multisensor 6? Does it update reasonably fast?

I use a Zooz zse40 in one bathroom and an Iris 3rd gen motion sensor (IL071?) in another. The zooz is nice because you can adjust the humidity sensitivity.


I use the new gen 3 motion sensor from Iris like Jimmy. They can be found on eBay pretty cheap for used ones. New one are hard to find, but they’re out there.

I use the Xiaomi humidity sensors in both bathrooms. For the last year they have been fast to update and accurate as far as I can tell. Haven’t gone offline either. Price is right as well.

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The most reliable humidity sensor I’ve found is by a user on these forums who makes his own, and shares them with the community when he can. They are USB powered, you also get temp, luminance and pressure sensors on-board, and they work as Zigbee repeaters! Cheaper and better than anything commercially available.


Zooz 4in1. Hardwire that baby and never have to worry about changing the battery. Humidity sensing works great!

I also use Xiaomi but recommend Zooz for reliability.


@Alwas. Thanks for the kind word. I really appreciate your support.

I have a few modules available to share in case anyone need it. As repeater, it is one of a Zigbee Repeater that would work with Xiaomi devices.

Here’s a listing for some used gen 3 Iris devices: (~$15, or make an offer!)

I installed a Zooz 4-in-1 in my master bath about a month ago. I adjusted the sensitivity to +/- 2% RH and it works great. I set it up using a DTH that was recommended from the Zooz support website. One thing you need to know is that it will check the humidity every 3 minutes. So if you are expecting something faster than 3 minutes you may be disappointed. The 3 minute response time for me works OK…I have it set up to turn on the fan upon a rise in RH above 65% and turn it off upon a drop in RH below 65%.

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+1 on the Xiaomi (Aqara)

I noticed eh IRIS reports humidty every 3 minutes, is the Zooz any faster?

In my experience, using the DTH that I am, the humidity on the Zooz 4 in 1 updates about every 3 minutes, if the humidity is changed beyond a trigger point, that I have set at 1% humidity. I believe this is so to extend the battery life.

This works for me in controlling the bathroom fan based on a humidity setpoint.