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  1. #1

    Aprilaire solenoid problems

    Installed an Aprilaire 400 yesterday and could not get the solenoid to kick in when hooked up to the humidistat. I had my 24VAC on the control. When I hooked up the solenoid directly to the 24VAC coming out of the furnace it worked fine so I have eliminated the solenoid. I also have my 24VAC on the terminals for the humidifier until the solenoid is hooked up then it drops to zero. I had another humidistat on the truck and that did the same thing.

    Any suggestions. Thanks.

  2. #2
    Join Date
    Aug 2009
    Beatrice, NE
    Is there a outdoor sensor on the humidistat.

  3. #3
    There was and when that did not work I went to manual mode. Which is where I had it when I was doing my troubleshooting. The solenoid did not operate in the test mode either when I had it all hooked up.

  4. #4
    Join Date
    Aug 2009
    Beatrice, NE
    What are you using for a blower interlock, a 50 relay? Go back and recheck your wiring diagrams, sounds like you put wires on the wrong terminals on the humidistat..

  5. #5
    I hope not as I have done one of these before but it is entirely possible. I have my 24VAC incoming to the R & C. I have the solenoid hooked up to the H and my outdoor temp sensor or resistor for manual mode hooked at ODT. I did not hook up the interlock relay as my 24VAC only comes on when the furnace comes on.

  6. #6
    Join Date
    Dec 2007
    specifically, how/where are the wires landing in what humidistat?

    sounds like no 24V to solenoid through humidistat. either incorrectly wired, bad humidistat or incorrectly set up since you know the solenoid works if powered directly.

    as was said, check your wiring again and it most likely will be there. the info, lacking specifics sends me in that direction.
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