Instructions / Assembly

29
Accessory devices
The ecobee3 can control an accessory HVAC device like a
humidifier, dehumidifier, or ventilation device from its ACC
terminals.
If you have 2 wires at the thermostat from the accessory,
then your accessory is externally powered. If you have only 1
wire then it is internally powered.
ACC-
ACC+
24V
C
ACC-
ACC+
24V
C
Y1 Y2 W1 W2 R C G
Accessory device
ecobee3 terminals
HVAC
control board
Note: You will need to configure the accessory device when you
first power on your ecobee3.
Option 1. Externally
powered wiring
Option 2. Internally
powered wiring