Question about Aprilaire 700 Humidifier

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Aprilaire 700 never shuts off

So I turned my humidifier on (aprilaire model # 700) for the first time since I moved into the home (03/07). At first when it came on it was leaking water everywhere. I popped off the cover and cleaned out the water panel (wire mesh) and plastic housings as best I could. I put it back together and fired it up again and no more leaks. However, the thing runs constantly (regardless if the gas furnace is running or not). I would assume the humidifier should not run when the furnace isn't working.

Any advice?

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  • smashclash Jan 25, 2009

    I should clarify. I left the unit on over night. at the time I left it both water was cycling through and the fan was blowing. This was regardless of the fact that the furnace was on or not.

    However, this morning I went and checked on the unit and only the fan was running (the furnace was off). I tried turning the unit to test mode to see if the water would run and it would not. Only the fan would run.

    So now all I have is a unit that will run the fan -- constantly regardless of the furnace working and no water whatsoever.

    This said are you sure it's the solenoid?

  • smashclash Jan 25, 2009

    Thanks. But I would think that whenever the unit was initially installed it would have been wired properly. If that's true, and I see no reason why it wouldn't, how could the wiring get mixed up due to lack of usage?

  • smashclash Jan 25, 2009

    And I doubt the fan wiring is my only problem. Because as of now I'm not getting any water either.

    So to recap: This is were my unit currently stands:

    -When turned on, only the fan runs. The fan runs regardless of the furnace being on.
    -No water is now cycling through the system. Initially when I put the unit back together last night, everything was running (water and fun) when the furnace was running and when the furnace was off.

    -As it stands now, all I have is a fan that runs constantly and no water whatsover. This is the same if the unit is on one of the #'s on the humidistat and when I turn the humidistat to "Test".



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Thanks for your question,
Sounds to me like you have a bad solenoid valve in your Humidifier, this will need replaced, the solenoid is supposed to open and close when there is a call for humidity only when the furnace is running, then when the proper amount of humidity is sensed by the humidistat, then will it shut off, with the solenoid not working it will let water flow through like an open faucet, the solenoid is the componet that the 1/4in copper tubing connects to at the humidifier, has two wires running from it, you will need to shut the power off before changing this out, also shut the water off at the valve at the other end of the 1/4in copper line, or you might get soaked,please be careful when installing the new solenoid, making sure the water line connection is secure, or you will have leaks, hope this was helpful, please leave a rating, thanks again for your question,

Posted on Jan 25, 2009

  • Dale Koehn
    Dale Koehn Jan 25, 2009

    Thanks for the Clarification,
    I thought that the water wasnt shutting off, well it seems you have a wiring problem, it would seem to me that the fan circuit is wired worng and it keeps the unit running 24/7, you will need to call in a service tech to find where the faulty wiring is, this system is a little to complicated to have you rewire the entire thing, try to find a good hvac company, you still may need a solenoid, but now that you have enlitened me a little more, this action would be the best for you, hope this is of help, thanks again,



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