# wiring humidifier to Goodman furnace ignition control board



## yuri (Nov 29, 2008)

Do you have air conditioning?

Some of those older Goodman's had no terminal strip and the thermostat wires just hang in the air and connect to the thermostat/tstat wires with wire nuts inside the cabinet.

The terminal on the board may be 120 volts and it needs to be tested to ground or it may damage everything.

If you trace the tstat wires back from where they enter the furnace they should go to a power transformer which has a hot and neutral connection. Red usually is hot and blue or yellow on it is neutral.

If you have AC they go to Y from the tstat (cooling signal ) and the other to neutral on the transformer.

You will also have a W from the tstat (heat signal ) and you could hookup your humidifier there and the other wire to the transformer neutral. It will get turned on as soon as heat is called for.

Make sure the humidifier uses 24 volts not 120 volts and post the brand and model # here.


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## silver mirage (Sep 12, 2017)

The screw terminal on the board is labeled HUM and 24 VAC.
The humidifier is an Aprilaire 600M.
And yes, I do have air conditioning.


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## yuri (Nov 29, 2008)

What you need to do is trace the 2 tstat wires from the outdoor AC unit back to the furnace.

One of them must go to Y from the upstairs tstat and the other goes to C common on the transformer.

Then turn on your furnace and with a AC voltmeter connect it to the 24 volt HUM terminal and the C common from the transformer.

Once the burner runs and the fan starts it should get 24 volts AC. If so then hookup the humidifier to them.


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## silver mirage (Sep 12, 2017)

I'll do as you say and let you know how it turns out. Thanks again.


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## yuri (Nov 29, 2008)

Yur Welcome:smile:

You need to press in the door switch to get the furnace to run. Duct tape it in or get a helper.


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## beenthere (Oct 11, 2008)

GMPs are well known for popping their crimp rings. Please inspect, or have your heat exchanger checked for popped crimp rings. Its a safety issue.


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