AprilAire 4655 Manual Whole-House Duct or Wall Mounted Humidifier Control Humidistat for AprilAire Whole-House Humidifiers Low Voltage 24VAC

After my humidifier stopped working abruptly, I called the original installers to inspect the unit. At first they said it was a power issue and needed to install a new transformed. I paid them about $200 for the job, and the unit worked initially, then stopped functioning again. After another call out, they now said the humidistat was shot and needed to be replaced. The part was under warranty, but they wanted about $200 to install the replacement part. I asked the manufacturer to ship the part directly to me, but they refused, stating they would only issue replacement parts through their authorized network. In short, I was out of luck. Rather than pay $200 for five minutes worth of work, I ordered this replacement part to install myself. Everything you need is included. The prior humidistat came off with just four screws, and this one installed just as easy. Unit started functioning again right away. The humidstat seems more or less identical to the old model, I just hope it will function a little longer. Overall, an excellent alternative that installs with very little effort. Has been working fine for several months. Read more

Update: This Winter will be 2 years since install and unit still working with no issues. ---------------------- This review is to help anyone who might have an older almond colored Aprilaire model 550. Pop off your old humidistat and make sure it is a 2 wire system. Since this 4655 humidistat is designed to work with a 2 wire system, you won't have any issues if the existing is the same. After removing old unit just wire this up, no need to worry about polarity. You can install the 2 wires to this unit whichever way you want. Only thing you may want to double check is the size of your pre-installed humidistat. My cutout from the old humidistat was larger than what this required, but I did some McGyvering and got it to fit in the same location. Otherwise you may need to cut a new hole. So be prepared for that possibility. This solved my issue of no water coming from my solenoid valve. Now we are good to go this Winter. Read more

This is the only branded humidistat I could find when my 20 yo Honeywell Humidipro failed. Honeywell obsoleted the Humidipro (Thanks, Honeywell!). I bought it knowing it required a larger ductwork opening to fit. I was pleasantly surprised that the actual humidistat inside the plastic shell is the same as the Humidipro! It was a super easy to swap out the humidistat and keep the Humidipro case so I didn't have to cut ductwork. Ended up being a very fast DIY job! Read more

First impressions: the humidistat is grey NOT white. I have had it for a day now and seems to be working right. Some ppl have commented about the need to cut drywall for installation. Nowhere on the instructions does it say to do so, however, I can see why some ppl do so that the unit is perfectly flush to the wall. I want simple install so I will not be cutting drywall. I had a red and white wire was all and hooked up in seconds, super easy. My old humidistat had more temperatures so you could keep the windows clean of moisture. I wish this had more of a guide for humidity/temperature levels. Overall, works and makes my house look not so 70's anymore. Update: set device at 35% humidity and as shown in picture, this thing is right on the money. Have had it now for about a month. Very pleased. Just wished it was actually white... Read more

Replaced our old humidistat which was not doing a good job of keeping the humidity level where we wanted it, so the house felt cold. Easy install. Working well. Price reasonable. Read more

This manual panel save my life!! We are trying to figure out the whole house humidifier over a week and HVAC Pro came multi times and made diagnose. We Purchased new unit and new auto panel but none of these work… but this manual works! So happy finally our system back to normal. Something too complicated is a bad idea. Simple is the art of engineering. Read more

BEWARE: It's NOT white! Otherwise easy to install and works perfectly. Aprilaire support, whom I called, says the item really isn't white, it is listed incorrectly on the Amazon website. It is really grey. And now that I'm looking, eBay sellers have it for 50% less than what I paid here. Just saying... Read more