Aprilaire 760: No power from humidistat or furnace controlled outlet

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Old 02-18-15, 08:56 PM
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Aprilaire 760: No power from humidistat or furnace controlled outlet

This seems like a very helpful forum. I was going to post on an existing thread, but since they are several months or years old, it seemed better to start a new one. I've read through a lot of the existing posts and have done a bunch of troubleshooting. In the end, after making sure the water supply, solenoid valve and humidifier fan worked, I found there is a problem with the power. I noticed the power outlet controlled by the furnace where the humidifier is plugged in doesn't have any power, although the outlet for the electronic air cleaner in the same box works. Temporarily, I used a different outlet. When I connected the two brown wires, the humidifier began to work just fine. I tested the wires from the humidistat, and there is no current even when the furnace is on and the humidstat is set for cold weather. Is it some issue with a current sensing relay or something else? Thank you very much in advance!
 
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Old 02-19-15, 07:21 PM
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Welcome to the forums.

Usually best to start a new thread.

You supply confirmed 120v to the humidifier and short the two brown wires and the system works normally. Does the humidifier also work with the humidistat in place ?

If yes.... it sounds like your receptacle has a wiring problem. The air cleaner gets 120v when the blower is running and the humidifier gets 120v when the inducer circuit is energized.

You'll need to trace your receptacle wiring. It may go to a terminal marked HUM on the control board.
 
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Old 02-20-15, 12:43 PM
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Pete, thanks for the welcome and reply!

I should mention the furnace, humidifier, and humidistat have worked fine for many years. This is the first time I am having this problem. The humidifier does not work when I have the humidistat wires connected to the humidifier since there is no current running through the humidistat wires anymore, so I have just connected the brown wires to bypass it. Would the humidistat be connected to the power supply via the control board?

When the furnace turns on, one of the receptacles in the outlet turns on (the one for the air cleaner), but the one for the humidifier does not. I am not sure if the receptacle is bad or if there is something else that controls it. I will open up the furnace and check out the control board - thanks for the suggestion!
 
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Old 02-20-15, 01:17 PM
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Fixed it! After opening the furnace, I noticed an orange wire that was not connected to anything and the HUM terminal did not have a wire in it. Connected it and turned the furnace on and it works with the humidistat. It seems like the tech that replaced my blower motor this summer disconnected the humidifier wire. Thanks!
 
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