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Solenoid on Aprilaire 700 still open after heating - Turns off at humidistat

Solenoid on Aprilaire 700 still open after heating - Turns off at humidistat


Old 11-29-14, 08:41 AM
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Solenoid on Aprilaire 700 still open after heating - Turns off at humidistat

I have an Aprilaire 700 I installed myself. I am attempting to do it myself but I have an issue with the solenoid not getting the signal to close. First simply my wiring diagram is as follows:

W --> Humidier --> Humidistat --> C

W and C are on the furnace board and the furnace is a Goodman GMS59155DXA. I can't seem to find any information regarding this model. I wanted to wire it off the pressure switch but mine does not have a brown wire coming off of it....just yellow and red. I am using a manual humidistat (Honeywell 9808B).

So when the furnace initially has power and I turn on the humidistat all the way to ON nothing happens...meaning the water solenoid does not open. As furnace fires up so does the Aprilaire as it should. Cuts off shortly before furnace cuts off. After that the water solenoid continues to run. If I turn the humidistat off the solenoid closes and the water stops. If I turn the humidistat on again it remains closed until another call for heat.

It seems the solenoid is working just not getting the right signal. Should I wire it differently?


Edit: I forgot to add that there is not a HUM terminal on my board.

Last edited by John.270; 11-29-14 at 09:20 AM. Reason: More information
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Old 12-05-14, 03:22 PM
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Welcome to the forums.

Sorry I missed this post.

As a professional I don't connect a humidifier to a thermostat. It's not designed to carry the load of a humidifier. In the drawing below a current sensing switch is used that knows when the blower is on and turns on the humidifier. You can also use a relay connected to the thermostat. I tried to find detailed info on your furnace but I believe the model number is incorrect.

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