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

Not that I understand the functionality, but it replaced the same one we had. My AC guy installed and we've been fine.

The Aprilaire humidistat model 4655 color is a pleasing light gray, not white, not very modern looking, but better looking than the orig model, and easy to install with 2 screws, and electrically using only 2 wires. I bought the 4655 humidistat Oct 2019 because the old Aprilaire humidistat plastic housing color turned deep yellow after 20 years - quite an eyesore.Mounting holes for the 4655 are different from the old humidistat which has no model number that I can find. The old humidistat had top left and right mounting holes; the 4655 has center top and bottom mounting holes; comes with two plastic wallboard inserts and screws. I was able to easily mount the 4655 over the old area shifted somewhat right and up, and hiding the existing wall hole for the two wires. I mounted it on our first floor next to our Carrier Edge thermostat; not near the furnace/humidifier which are in our basement. Use a drill for the two wall inserts for a clean mounting.I also purchased an Aprilaire 4837 annual maintenance kit ($60) for our model 560 Aprilaire humidifier replacing most internal parts; find online. The owners manual is also online and identifies all Model 560's parts. With a voltmeter I measured 24v AC across the two humidistat wires. So by Oct 2019 I have maint kit 4837 and the new 4655 installed, and I am waiting for a plumber to replace the 20+ year old saddle valve which is not supplying any water, and most likely not working for years.Nov 1 2019 Plumber arrived and abandoned the old saddle valve on the cold water pipe, and installed a T-valve on the nearby hot water pipe.I also ordered the humidifer solenoid valve (sku 4040, 24vAC, 125 psi, 3/64" orifice) that covers a range of Aprilaire humidifiers including model 560; notes said to replace it after 10 years, and its been longer than that. Warning: check Aprilaire website for the 4040 solenoid valve for nomenclature/specifications to assure that you order the same part if you order elsewhere; I found other Amazon sellers either have photos that obscure the nameplate or do not show written specifications which I consider both fraud. Received and installed the Aprilaire brand 4040 24vac solenoid on 11/6/2019, and the humidifier system appears to be working due to droplets in the clear drain tube; mother nature is keeping us at 41% rh on 11/6/2019, so no dire need yet for the humidifier.fyi, for years the 3-point outside temp/relative humidity range printed on the face of the humidistat confused me; why so short a range of just 3 temp/rh values, and were the plus and minus signs a difference in temps or an actual temp. Then an Aprilaire distributor informed me the 3-pt range on the face is a very truncated range; the owners manual lists an expanded range and the temps are truly outside temps. This manual humidistat model 4655 can't sense outside, so you play the part in telling the humidistat what the outside temp is by adjusting the knob. And the knob value you turn to is the relative humidity manual setting, which is a max rh value that prevents inside condensation, on windows eg, to prevent mold; so choose either the max rh value for the outside temp or a lower rh value. So I set it for the day's low temp; somewhere between 25 - 35% rh for winter.Also while replacing the water panel, you can see inside the return air duct, so you can vacuum the return air duct for as far as you can reach.

Little tough to install because where the screws go you cannot get your fingets in to hold the screw. Need a magnetic screwdriver.

Does what it is supposed to do. Easy to install. I used as a replacement and had to make a few modifications as far as screw placement.

Is not white.

Very easy to install.We’ve been in this house for 2 winters. I never could get the humidifier working properly until I replaced the humidistat. Now it works like a champ.

I thought the problem was the solenoid valve but ended up just needing to replace this. Probably 15 min project and way cheaper then hiring a pro.

Obviously NOT white like it says.. More of an ugly brownish gray.. Minimal effort to install.

Sur la photo l’appareil est blanc et en réalité il es gris

I bought this item to replace an old one and needed white but this is grey. Would have not purchased if I knew

Perfect fit humidistat replacement for a Lennox Climate Air furnace humidifier. Much more cost efficient than the 700$ the dealer wanted to install a brand new unit.

We had an Aprilaire auto humidistat that varied the humidity depending on the outside temperature. However the outside temperature sensor had to be replaced twice, and it failed again. I tried the manual override by adding a resistor to the auto humidistat but this did not work since the auto humidistat was also faulty. I replaced a faulty auto humidistat with this manual one and it works perfectly. It was very easy to install.

It is easy to replace the original unit with this one. Originally had problems in that water was not flowing into the humidifier. A quick check with a multi-meter to the simple input and output leads confirmed that the original humidistat was not working. The replacement was nearly identical, and installation was a snap. Save money, and do it yourself!