Review on Aprilaire 4655 Manual Humidistat by Chad Myers

The color of the Aprilaire Model 4655 Humidistat is a nice light gray instead of white, doesn't look very modern but looks better than the original model and is easy to install with 2 screws . and electric with only 2 wires. I bought a 4655 humidistat in October 2019 because the color of the plastic body of an old Aprilaire humidistat has turned dark yellow after 20 years - quite unpleasant. The mounting holes for the 4655 are different than the old humidistat which has no model number that I can find. The old hygrostat had mounting holes at the top left and right; 4655 has center top and bottom mounting holes; comes with two plastic wall plate inserts and screws. I was able to easily install the 4655 over the old section by moving it slightly to the right and up, covering the existing hole in the wall for the two wires. I installed it on our main floor next to our Carrier Edge thermostat; not next to the stove/humidifier that's in our basement. Use a drill for the two wall inserts for a clean installation. I also purchased the Aprilaire 4837 Annual Maintenance Kit ($60) for our Aprilaire 560 humidifier model, which replaces most of the internal parts; find on the internet. The user manual is also available online and has full details of the 560. Using a voltmeter I measured 24VAC across the two wires from the humidistat. So as of October 2019 I have a 4837 service kit and a new 4655 and I am waiting for a plumber to replace a 20 year old poppet valve that is not supplying water and has most likely been out of service for years. On November 1, 2019, the plumber came and discarded the old poppet valve on the cold water line and installed a T-valve on a nearby hot water line. the Aprilaire line of humidifiers, including the Model 560; the notes say to replace it after 10 years, whichever was longer Warning: Visit the Aprilaire website to find the 4040 Solenoid Valve for the nomenclature/spec to ensure you order the same part if ordering elsewhere ; I have found that other Revain sellers either have pictures that hide the nameplate or do not show the written specs which I believe is a scam. I received and installed an Aprilaire brand 4040 24vac solenoid on 11/6/2019, and the humidifier system seems to work due to drips in a transparent drainage tube; November 6, 2019 Mother Nature keeps us at 41% relative humidity, so there's no pressing need for a humidifier just yet. FYI, for years I was confused by the three dot outdoor temperature and relative humidity range printed on the face of a humidistat; why such a short span of only 3 temperature/relative humidity readings and whether the plus and minus signs were a temperature difference or the actual temperature. The Aprilaire dealer then informed me that a 3-point area on the face is a very shortened area; The manual points to an extended range, and the temperatures are really prohibitive. This model 4655 manual humidistat cannot sense the outside temperature, so you play the role of telling the humidistat the outside temperature by adjusting the knob. And the value of the knob you turn is the manual relative humidity setting, that is the maximum relative humidity value that prevents internal condensation, e.g. B. on windows to avoid mold; Therefore, choose either the maximum relative humidity value for the outside temperature or a lower relative humidity value. So I set it to the low temperature of the day; anywhere between 25 - 35% relative humidity for the winter. Also, when replacing the water plate, you can see the inside of the return air duct, so you can suck the duct as much as possible.