The Aprilaire 4655 Humidistat is designed for low voltage service to control humidification equipment. An increase in relative humidity expands the nylon ribbon which opens the control switch to stop operation of the humidifier. A decrease in relative humidity reverses the process and closes the control switch. Can be wall mounted or mounted on return plenum. Includes plenum cutout template (4 5/32" X 2 7/16"). For duct mount, locate at least 6" upstream of humidifier, humidifier bypass ductwork or fresh air intake ductwork.
We bought this to replace an old gold humidistat that was probably from the 80s or earlier. The knob on the old unit was broken off and couldn't be repaired. The new unit is slightly bigger but we made it fit. It took us a long time to figure out that the two posts for wires simply made a circuit and there wasn't a positive or negative. Either that or we got lucky with the first combination we tired. At any rate, once we finished deliberating about positive and negative posts, it took about 10 minutes to install it. It probably would go faster if someone with ANY amount of experience was doing it. But, we managed to get it on and running and not electrocute ourselves, so it's a win!
2/28/2013
4.0
Simple-good product
By tom
from pa
About Me Homeowner
Pros
Cons
Doesn't Fit
Best Uses
Whole House Humidifiers
Had to make a metal back plate to fit the existing hole. Saw that a back plate used to be offered but no longer available. Easy wiring job. Talked to tech support-very helpful. Would buy again
2/5/2013
5.0
Perfect Replacement
By drmikeb
from Summit, NJ
About Me Homeowner
Pros
Fast Easy Replacement
Works Fine
Cons
Best Uses
Original humidistat died after 10 years. This OEM replacement was very good price, works fine. Some minor duct cutting required from original.
1/1/2013
5.0
No complaints, product works great.
By Phrank
from Crystal Lake, Il.
About Me Retired homeowner
Pros
Durable
Energy Efficient
Good Fit
Cons
Best Uses
Whole House Humidifiers
The delivery was ahead of promised time.
12/20/2012
4.0
Fast service, easy to install
By Handyman
from Jenisom, mi
About Me Handyman
Pros
Cons
Best Uses
Whole House Humidifiers
Fast service
12/14/2012
4.0
It keeps you comfortable
By lg
from Hoffman Estates,Il
About Me Homeowner
Pros
Cons
Best Uses
Whole House Humidifiers
Replaced an "automatic" electronic humidistat with this unit. Much less expensive than unit it replaced and performs just as well.
3/2/2012
4.0
Good product and service sofar
By Chuck
from Rensselaer, N.Y.
About Me Handyman, Homeowner
Pros
Easy to install
Energy Efficient
Good Fit
Cons
1rst one only lasted 3yrs
Not Durable
Best Uses
Whole House Humidifiers
The Aprilaire humidistat works great,easy to install, however i had to replace the original one in just under 3 years. ordered online no problems at all.Over all happy with the Aprilaire humidifier and there service.
1/24/2012
5.0
A Great Improvement over previous model
By Stephen Home Handyman
from St. Louis, MO
About Me Handyman, Homeowner
Pros
Durable
Good Fit
Superior replacement
Cons
Best Uses
Whole House Humidifiers
I had to replace a broken older model humidistat, and this one is designed to be much sturdier and long lasting. Internal parts are protected by metal cover, unlike older model which had parts exposed and prone to damage. A perfect fit to replace older model, too.
1/11/2012
5.0
Exactly what I needed
By Ron
from West Bend, WI
About Me Homeowner
Pros
Durable
Energy Efficient
Cons
Best Uses
Whole House Humidifiers
I received this product in 3 days and installed it myself. My heating contractor wanted to charge me $267 for a part that cost [$]. He is no longer my heating contractor!!
1/5/2012
(2 of 2 customers found this review helpful)
3.0
One part with short life
By Paul K
from Schenectady, NY
About Me Homeowner
Pros
Energy Efficient
Good Fit
Cons
Has failing switch
Not Durable
Best Uses
Whole House Humidifiers
This item replaced an identical item in which the micro switch failed after only two years. The one before that failed the same way after one year. Would be an excellent product if the switch was more durable.
