Question about hard-wiring humidifier to furnace

I just installed a Desert Spring humidifier and I want to hard-wire it to the furnace board. I have one wire coming from the humidifier itself and one from the humidistat. Out of the box, they both connect to a transformer that plugs into a wall outlet. I don't have an outlet nearby though.

I had cut the transformer off of the wire, stripped the wire back, twisted the 2 wires together and crimped on a spade connector and hooked it up to the EAC connector on the furnace board but this didn't work. I'm thinking I shouldn't have twisted the 2 wires together but maybe done something separately with them. What should I have done instead?

Thanks!!

 

I don't like writing this but you just voided any warranty you had on the humidifier.

The "transformer" (may be a D.C. power supply) provides a low-voltage power source to the humidifier, by cutting it off and trying to wire it directly to the furnace you are trying to power the humidifier with 120 volt A.C. and that simply won't work. It would totally fry the humidifier if you had connected the two wires across the humidifier terminals in the furnace. Since you connected BOTH wires to the same terminal you may have lucked out.

Reconect the transformer as it was originally. Then using approved methods attach an outlet to the furnace wiring the outlet silver-colored screw to a tab on the furnace board labeled "Neutral" and the brass-colored screw to the tab on the furnace board labeled for the humidifier, or alternately the tab labeled "EAC". The green screw on the outlet will be wired to the furnace frame.

Hopefully your humidifier will still work.

 

OK, well before I read your reply I went home at lunch and wired it into the 24v thermostat jacks on the furnace board. I hooked up one wire to "C" (labeled as 24v hot) and one to "G" (labeled as ground). The humidifier drum started turning immediately and everything seems to work fine. Any problems with this setup?

Also, I'm not sure that I voided the warranty as the manual states that alternatively it can be hard-wired to the furnace's 24v board instead of plugging the transformer into an outlet.

 

You need some type of contro that only lets the humidifier run when the blower runs. This can be done a few ways.

1. An A50 current sensing relay.
2. A sail switch installed in the duct work.
3. If your control board has a connection labeled "HUM" for humidifier.