Electrical – Furnace shutoff switch outlet only hot when furnace is running

electricalfurnacehumidifierhvac

I have an old Aprilaire 700 powered by the 110v outlet on the side of my furnace. I recently replaced the old humidistat with a newer Aprilaire 60 Digital. This humidistat comes with the blower control option – when it's too dry it will activate both the humidifier and blower without needing to have the heat on. My problem is that the outlet on the side of the furnace that the Aprilaire unit is plugged in to is only hot when the heater is running. This results in the humidistat turning on the furnace blower but the humidifier's own fan is not powered on. By running an extension cord across my basement to a different outlet I was able to get this setup to work correctly.

Lennox/White-Rodgers 46M9901
Lennox/White-Rodgers 46M9901

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The outlet / cutoff switch

I'd like to get that outlet to be hot all the time, or hot anytime the blower is on.

I plugged an outlet tester into the outlet, confirmed it lit up with heat on. When I disconnected the HOT HUM quick connect fitting, the outlet tester turned off. I tried touching the humidifier quick connect to the HOT EAC and NEUTRAL EAC terminal while holding the door safety switch, but the outlet tester did not light up. Should I have unplugged the EAC wire and plugged the HUM wire in completely? I figured I could just move HOT HOM to HOT EAC but that didn't seem to work.

Note: I do have an electric air cleaner, but I'm using regular filters now. I do not need the EAC powered up.

Best Answer

Right after I asked this question I realized the blower needed to be running for EAC to have power.

:facepalm:

I moved HOT HUM to HOT EAC and now the humidistat will start the blower, which will power on the outlet that powers the humidifier's fan unit. I also unplugged NEUTRAL EAC since I'm no longer using it. Let me know if I did anything stupid here.