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Diagnose humidifier issue

chrisyngchrisyng calgaryMember

What's the best way to determine if my Ecobee 3 is having issues with turning on my humidifier? Here's the scenario:

Honeywell humidifier has been hooked up and working for about 2 years with the ecobee 3..
one side of the humidifier solenoid is hooked up to the ACC+ on the ecobee, and the other side of the solenoid hooked up the the "C" common connection on my furnace board..

when the call for heat comes on along with call for humidity, I get no water flowing through the solenoid..
I took my multimeter and checked for voltage by hooking one probe to the wire going to ACC+ and the other probe to the wire going to "C" .. I see 0 volts on the multimeter.. shouldn't I be seeing 24Vac?

I assume that the C wire is good since the ecobee is getting power.. so that would mean the issue could be with the ACC+ side?

any suggestions on how to diagnose the ecobee side of things?



  • kevinmcckevinmcc Macomb, ILMember

    My opinion the best way to hookup an accessory is to use an external transformer and two wire method.

    But if your setup was working, there could be a few things wrong. Bad wire, bad internal relay in Ecobee, or bad solenoid. Being no voltage from ACC+ to C, I would assume either bad wire or bad internal relay in Ecobee. At the Ecobee end if you jump Rh to ACC+ does the solenoid work? If so, Ecobee relay is bad. If not, likely wiring issue.

    If wiring issue, make sure solenoid has good connect to ACC+ and C. A continuity test from wire going to ACC+ to C should show an electrical path, meters usually beep if working.

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