Aprilaire humidistat

[gibrenob]

I do a lot of PM's on furnaces with Aprilaire humidifiers. I've noticed lately that many of the model 600 units have gotten no water flow across their panels in the past heating season. The humidistats are in "manual mode" in which no outdoor sensor is used, and the setting is at 5, (35%). I've checked jumper locations, and wiring, and it's always correct. They will only work in "test mode". On the older humidistats, you could hear an audible click when turning it up, and on a day when they all seem to be coming on between 25% and 35% humidity, the ones that I am questioning do not, (except for test mode). Has anyone else seen had this problem?

[Senior Tech]

Have you checked the humidity level in the home when you checked the humidifer?
Can only be 2 things, either there has not been a call for humidity or they are installed incorrectly or broke...oh wait, that's 3 things isn't it...

[80percenter]

I've noticed the same thing. The older humidistats come right on and the newer ones don't. I recently installed an AA 600 in my home and it wasn't coming on either so I checked the RH and it was about 40% so I'm going to wait until the temp drops a little to check again (the weather's been unusually warm for January ).