I am installing a Aprilaire 700 Humidifier on a Goodman GMNT gas furnace the
Furnace control board is a white rogers 50T 35-730 it has separate hum 24v
Terminal and hum 120v terminal the Aprilaire 700 Humidifier includes a built in 110v to 24v transformer which one should I connect it to and also where do I connect the common wire to

Thanks

I see no reason to complicate life with a second transformer. If the furnace already has a 120 Volt hum terminal, it may already be set up to control a humidifier. Wiring the hum terminal it to the load side of relay in the humidifier and the white wire of the humidifier to the main bundle of white wires in the furnace may be all you need. If the wires to the humidifier are both black, it doesn't matter which one goes where.

I have the same problem and don't understand the answer. What did you do? I am replacing a 112 model Aprilaire with a 700M model and I am not sure what to do with the transformer.

Use the 120v connection on the control board and the humidistat you have. You will not get power for the humidifier until the blower kicks on in heating mode. The two low voltage wires going to the humidistat is to complete the circuit only if you need humidification when the blower is running in heat mode.

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Originally Posted by T-Top

Use the 120v conection on the control board and the humidistat you have. you will not get power for the humidifier until the blower kicks on in heating mode. the two low voltage wires going to the humidistat is to complete the circuit only if you need humidification when the blower is running in heat mode.

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Thanks for the response. I have it set up the way you indicate but I don't get water or motor to run. I have super studied the diagram on this model from Aprilaire and I think I have it figured out. Will attempt implementation this weekend and advise of success. Picked up an add'l electrical box to install the 24v transformer in since it doesn't fit on the outside of a box.

I also have the same problem. I'm replacing an Aprilaire 760 with the 700m. I have a red and white wire coming from the humidifier, and a white and red/white wire coming from the furnace. How do I connect them to get the humidifier to work?

Another update - I connected the two red wires to the two terminals in the humidistat, and joined to two white wires to each other. The furnace works, but the humidifer doesn't seem to be turning on. How can I tell if the humidifer is working?