I have a Rheem furnace model number GF801U125AS60. It was installed as a brand new unit 2 years ago. I am now trying to hookup the old humidifier(Aprilaire) to the furnace. The schematic on the furnace door shows a HUM relay, but I do not have or can't find a HUM terminal on the board. I have an L1, Neutral, M1, EAC, Heat, Cool. Is the HUM terminal in a location that is not obvious? If no HUM terminal I assume I need to purchase the relay?
Right, no HUM terminal on upflow models. Might find an adapter, I don't know. Good luck.
EAC is electronic air cleaner. I think that's typically 120V, not 24V, but it may vary depending on furnace. I think Aprilaire wants 24V. so, if it's 120V, you;d need a Xformer. Also, EAC will be active whenever blower is on, so humidifier either needs to be manually turned off in summer or have an outdoor temp sensor, in which case the Aprilaire I have turns off itself.
You could probably just connect it to the heat call terminal too. They don't tell you to do that, because I think they are concerned about placing the additional small load of the humidifier onto the furnace Xformer when they don't know it's rated capability and they figure it's too complicated for installers to figure out.
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