Question about Aprilaire 700 Humidifier

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Humidifier control .

Aprilaire 700 humidifier properly wired to outside sensor, to humidifier solenoid/fan and furnace. Works properly in test mode for 1 minute as stated in instructions. Solenoid/fan, water flow does not come on in any setting. I notice when juggling wiring going to control that the water panel change indicator and the red diagnostic light flickers off and on. Wiring to all terminals firm. Could I have a bad Humidifier control unit?

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Re: Humidifier control .

If humidifier was wired into thermostat circuit for power instead of seperate transformer , this can happen. you need to see if you voltage going to the solenoid valve. if you do , and it isn't opening, the valve is bad . this is assuming that it is using a # 50 relay to come on only when the fan runs . . make sure the water valve is open

Posted on Dec 28, 2007

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I had this problem several years ago. In order for the water to flow, the outside temperature sending unit must indicate to the controller that it is less than 60F. If not, the unit will not operate outside of test mode. Check the temp outside where your sending unit is (could the sun be heating that side of the house?) and ensure that the circuit to the sending unit is working. I had a bad wire splice inside a wire nut stopping the circuit. Took me a long while to figure it out.

If the outside temp and your sending unit circuit is ok, I wish you luck on your troubleshooting.


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