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I want to wire my furnace humidifier to my furnace so that when the humidifier goes on, the blower on the gas furnace will start to. My furnace has a terminal marked "HUM" for humidifier. Is that what I should use?
The furnace control pannel has the following 24 VAC terminals.
G (fan); B (24 V com); W (heat); Y (AC); R (24 VAC); There is also a separte 24 VAC "HUM" terminal.
I'm thinking I could connect my humidifier to the B and HUM terminals, but how could it also turn the blower on?
You would have to have an isolation relay installed that will energize the G terminal on the furnace when the humidistat calls for humidification. The G terminal had to be powered by the R terminal power on the furnace, you can't just run 24 volts to it from a separate transformer that's why you will need a relay. Let me know if you need help with that.
You don't want to run the humidifier solenoid off of the furnace R terminal, the HUM terminals don't do what you need them to.
It should, is the door switch pressed in ?
It will only come on when the heat is on, you wanted to signal the unit to come on when the humidifier called, it won;t work that way.