Ecobee3 with HUM Humidifier

I've wired my Ecobee3 thermostat to my current Furnace, with new 6-wire Thermostat Cable (the thermostat is straight up in the wall). However, it has a Humidifier connected via a HUM connection with another transformer, and I'm wondering how to wire that to the Ecobee.

Current Furnace wiring on R/C/W/W2/G/Y screws. The two extra wires on C and Y go to the AC Compressor.


Wiring at the bottom of the furnace control board. There are two wires coming from a transformer at the bottom of the box (lower right), one going to "HUM", the other going to "Neutral" on the high-voltage side of the transformer.



On the front (low-voltage) side of the transformer, there are two wires which go to the Humidifer (one going directly, the other going through a humidistat).







Misc:
Wiring diagram on the furnace door:

 

Welcome to the forums.

You will no longer need the transformer or humidistat.

You connect one wire from the humidifier solenoid directly to the C connection.
The other solenoid wire goes directly to ACC+ on the Ecobee. Set the Ecobee to one wire accessory.

The E3 and E4 connect the same way.
http://www.doityourself.com/forum/hu...0-ecobee4.html

 

Thanks - there is no concern with overloading the existing transformer? I'm just confused why there would be a separate transformer if the COM already provides the needed power.

 

Your original install took advantage of the switched HUM output which is 120v and is why the transformer use was mandatory.

You could have too many devices hanging on the internal transformer. You can add up the loads and subtract from the transformer rating.

With a 40w transformer....I haven't had any problems.