Replace Lennox iComfort s30 with ecobee smart thermostat

It is possible to replace a Lennox iComfort s30 with an ecobee smart thermostat premium on a Lennox SL280UHV, but it will take a little rewiring. 

My iComfort s30 thermostat smart hub slowly died after a power outage. I couldn't find a replacement part in stock, and the new upgraded hub would cost between $500 and $1200. 

The good news is that I was able to replace the iComfort s30 with an ecobee premium model. I selected the premium model because it was on sale and would work well with my whole house humidifier. 

Because the iComfort s30 and my outdoor unit were both communicating devices, I had to move wires from the 4-wire (R, I+, I-, C) terminals to the more standard non-communicating terminals (W1, W2, Y1, G, C, R, etc.) on both the inside furnace control board and the outside unit control board. 

I used the ACC+ terminal on the ecobee to control the AprilAire 600 Whole-House Large Bypass Humidifier. It's a one-wire solenoid setup. I removed the HUM connections from the control board and joined the red humidifier wire to the black ACC+ wire. The C connection stayed the same.

⚠ Always disconnect power to your HVAC before opening any part of it. You could accidentally short a wire and damage the system or shock yourself.

ecobee wiring setup
ecobee wiring setup


Original indoor unit wiring:

Lennox SL280UHV
Original Lennox SL280UHV wiring 

On the indoor control board, I moved the red, yellow, green, and blue wires to the terminals that matched up with the ecobee wiring terminals. Fortunately, I had three additional wires already in the bundle to connect the rest. 

For the outdoor unit, I moved the yellow wire from I- to Y1 on both the furnace and outdoor unit control boards. I left the green wire disconnected from both. (not pictured)

Final wiring for indoor unit:

Final wiring for ecobee with humidifier

The disconnected green wire on the left runs to the outdoor unit and is no longer used. 

Red and black wires with the blue cap connect the ecobee ACC+ terminal to the humidifier. 

W1, W2, G, Y1, C, R all run to the ecobee thermostat.

Y1, C, R run to the outdoor unit. If you have a communicating system, make sure to move the yellow wire to Y1 on the outdoor control board. 

⚠ Always disconnect power to your HVAC before opening any part of it. You could accidentally short a wire and damage the system or shock yourself.




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