Ecobee thermostat controlling humidifier


Old 12-17-17, 03:36 PM
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Ecobee thermostat controlling humidifier

Hi All,

I found this thread and it seems like a good place to start. I am having a tough time getting my humidifier to turn on. Even when I try to manually turn it on from the Ecobee, it doesnít work but the fan does, even when I only select the humidifier to turn on - it says fan is off

I have it wired just like this:

But it seems like acc+ will not fire for me. I checked and the solenoid works. I have continuity between the acc+ wire and the C wire, too. (I tied them together at the thermostat and checked at the furnace).

here is the ecobee

The one thing you can't see is the brown acc+ wire is wire nutted to the red wire of the humidifier solenoid. The white wire from the humidifier solenoid is the white wire also connected to the C terminal.

When the ecobee says the humidifier is on (in the manual troubleshooting settings), I get 0V at the acc+ wire in the furnace (other probe to common, or ground).

I am no longer using the 24V humidifier transformer on the furnace, but I donít think I should need to if I can get the 24V from the ecobee.

I have it set for 1-wire, evaporative humidifier

Any ideas on how I can

1) absolutely know that the Ecobee is turning on ACC+?
2) get this thing to work?

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Old 12-17-17, 03:49 PM
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Welcome to the forums.

That other thread was getting too long for another poster. Here you are in your own thread.

You should measure 24vac from ACC+ to C at the furnace when calling for humidifier. If you don't... the programming is wrong or the wire is bad.

You should be able to go to the stat, remove the stat, and touch the ACC+ (brown wire) to the R terminal. If the humidifier works ok..... the stat is the problem.
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