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View Full Version : Accessing main IC board on G40UH(X)


jayshaw91
Jan 10, 2010, 05:35 PM
I'm trying to DIY a humidifier. I see in the install manual for the furnace that there are two HUM connectors on the board. The silly thing is, I cannot for the life of me figure out how to get to this board to complete the installation.

I figured there'd be a handle or some obvious screws when I took off the burner access door, but I didn't see anything.

Anyone able to help?

Thanks!

hvac1000
Jan 10, 2010, 05:41 PM
Actually I do not recommend you use the circuit board in the furnace. You are better off using the 24 volt power source that came with the humidifier and using an air sail switch or a small relay designed to sense the blower motor current. The rerason I say this is the fact that depending upon the amount of curent the humidifier draws it can tax the board. Now if you know all that info and the board will support it then go for it.

jayshaw91
Jan 10, 2010, 06:15 PM
Well, seeing that the board has two clearly marked HUM connections (one is 120v, the other ground) I figured it was a no-brainer to go this route. FYI, I will have a 24v transformer between the humidifier and the main board. Does that change things at all? Also, this is just a bypass humidifier. The only thing drawing current is the solenoid from what I can tell. I'd think that since it is being stepped down to 24v it shouldn't make a big deal, but I'm willing to be told otherwise.

The instructions for the humidifier say I can wire this directly to the 24v circuit and forget using the relay or tap in to the 120v, but use the relay.

Another idea... I can get to the 120v wires easily. Can I splice in the transformer and just wire cap everything?

I have no idea what an air sail switch is.

Keep the ideas and thoughts coming!