Ventamatic XXDUOSTAT Adjustable Dual Thermostat/Humidistat Control for Power Attic Ventilators

Just purchased and installed, and I'm very satisfied.Some of the bad reviews claim poor accuracy - due to not understanding how these devices are supposed to work. That is, hysteresis is necessary - else you'll burn out your fan, and hysteresis causes (no requires) the setpoint to be higher than target as you go up, and lower than target as you go down.For example: Given temperature and / or humidity set at 70. If it switched both ways at EXACTLY 70 (both ways), then the fan would cycle too often and burn up as the fan on would lower (Temperature and / or Humidity), yet fan off would raise (T and / or H). So, the device is (must be) designed to turn on a little above set point and turn off a little below set point. That difference is the hysteresis. The more the difference, the less the device cycles the fan, at the cost of precision. BUT the average is always setpoint.These are mechanical actuators, and as such, hysteresis is not adjustable thus hysteresis is set larger as to protect all fans. Some very expensive digital models will allow the user to reduce the hysteresis difference, assuming the user understands enough as not to over cycle the fan.I'm trying to keep the attic cool and free of mold, so I'm just fine with having my temperature and humidity bounce between the two setpoints defined by hysteresis. I hope this helps.

This is a decent thermostat for the money. It took me roughly a couple hours to properly install the fan and wire in the thermostat. After turning on the power I set the humidistat to 60 and thermostat to 100. The thermostat is roughly 5 degrees high but the humidistat runs around 25% high. It ok for my shop but I also wired in a secondary switch to shut off the fan power. I definitely recommend this especially if it’s raining outside the fan will pull moisture into the attic. I also recommend installing a digital readout for temp and humidity so you can see what your attic is actually reading.

Does what its supposed to do and installation instruction were good too. My fan comes on when the humidity gets high. One point to understand is that when it is raining the fan will come on. That doesn't help the attic so I have a downstairs kill switch for rainy days. This is not the fault of the device so I kept the 4 star rating.Want to get a 5 star rating? Get another sensor to go outside and electronics that can tell the difference between outside and inside the attic. No use bringing in humid air when it rains, no use bringing in hotter air if the attic is cooler than outside, as happens early mornings in July. I would be willing to pay the extra dollars for that.

I've been very happy these thermostat/humidistat systems. I originally bought just one to replace an old thermostat-only box that had gone bad under my house. I have two exhaust fans under my home in the raised crawlspace. One is against a sold wall, blowing inward; the other blows outward through holes in the fence paneling. I figured since I needed to replace the thermostat, I might as well upgrade to the thermostat/humidistat since I live in a very humid climate. I was going to wait to place the second one until it failed, but recently decided to go ahead and swap that one out also, so that they can both run together like they're designed to. We've had a lot of humid days this winter, where the old thermostat would have never kicked the fans on, but they've been running a lot, making me feel much more confident that I won't have moisture in my crawlspace.As for installation, the instructions aren't really the greatest; it's just more of a diagram that doesn't really explain too well which wires are which, but if you have any electrical experience at all, you'll probably figure it out. I think I had to swap a couple wires the first time, so it was a little bit of trial and error.

I bought from 2 different sellers on this specific listing and they both sent the wrong part. It is not as advertised. The one in the picture used to be manufactured and goes down to 30% humidity. I called Ventamatic and they told me that they only manufacture the 50% humidity version now. So this listing needs to be updated to reflect what they are selling. The product works great, I have the 30% humidity version I found on Ebay but I wanted another one. If you are ok with the 50% humidity version, it works as advertised. We are just in very high and dry Colorado Springs so we need the low humidity version.

Geez! I can not sing enough praise about this fan.My previous home had an attic fan.So when we bought this new build. I didn't look to see if it was there in place. When I realized we did not have one I was puzzled as to why the builder never put it in to compliment the HVAC system. I guess thats the corners the builders cut these days.Any way after 6 hours of crawling back and forth in that rat maze that the builders call an attic, trying to avoid putting our feet thru the ceiling-once we flipped the switch on: Within an hour we felt a hugh difference in our 2 year old house. I wish we had done it the 1st year when we saw there wasn't a fan.The AC hardly even runs now-we have it set on 83 degrees and the attic fan at 100 degrees. And we live in Arizona.We are considering the 'humidistat' for the upcoming winter. Will post about that when we get it installed.

I had no problems fitting the wiring inside the case as some have commented. The humidity setting knob can be rotated all the way clockwise to turn on the fan for testing purposes. You can also cutout the humidity sensor by rotating the setting knob completely counter-clockwise to have it never turn on the fan, which is what I needed to do in the summer when the air was humid enough to keep the fan on most of the day. In our cold winter climate, I will set it to turn on around the 50 - 60% humidity level. The settings were within +/-5 degrees and percentage humidity compared to an electronic thermometer and humidity sensor placed near the switch. On warm days this summer, the upstairs rooms were noticeably more comfortable on the hottest days when the fan ran.

The humidity setting inPicture shows lowest at 30%!The unit shipped shows 50% as lowest.I sure hope if the arrow is in the middle between 50-0 I get 25%!Please let me know.Otherwise arrived in great shape.

Works great

Does exactly what it suppose to do, easy installation and easy adjustable. Work's flawless with my attic fan.

After about half a season of use in the greenhouse, it appears to get stuck often. Not turning on at pre set Temps and often not shutting down after temp is reached far beyond pre set.It does switch when you touch or smack the wall it is mounted on

Have not had a chance to install it yet due to cold weather so don’t know if it works yet or if it will do the job required