Troubleshooting accessory installations
ecobee SmartThermostat with voice control, ecobee4 and ecobee3 support most common HVAC accessories such as humidifiers, dehumidifiers, and ventilators. Accessories can be wired as a 2-wire or 1-wire, depending on how the accessory has been set up with your system.
Ventilators usually come as 2-wire accessories, while humidifiers and dehumidifiers can be both.
1-wire accessories terminate at the ACC+ terminal on the ecobee, and utilize an existing 24V power source from the HVAC equipment to se