Humidifiers and Dehumidifiers - Installing an Aprilaire Humidifier Control for Model 700 humidifier

I'm in the process of installing an Aprilaire 700 humidifier on a Bryant 398A furnace. I have questions about connecting the power source to the humidifier control. I have two options for the power source:
1) Accessory terminals on the furnace (24 VAC) or
2) External 24 VAC transformer with a relay

I believe I can use option 1, but I don't know which combination of terminals to use. Would I use "R + C", or "H + ?", or "GH + ?". I have the following terminals available" R, C, Y, G, H, GH, W.

Thanks for any assistance. :)

I would not suggest of "stealing" power from the 24 volts on the board. However, if your board has a "hum" or Humid" screw or wire tap, you can tie your transfromer on that. When the system is on, the 120 will power up for the transfromer.

The 700 should have it's own transfromer, and a 110 plug in. So that means you should use the the hum or humid screw/tap, and tire it to a plug to the side of the furnace.

If you tie it into the 24V power on the furnace You should get a higher voltamp transformer and put it in the furnace. So it is best to let it have its own transformer and put an A-50 relay on the blower wires to turn it on.


ED ;)