Troubleshooting accessory installations

ecobee4 and ecobee3 support most common HVAC accessories such as Humidifiers, Dehumidifiers and HRV/ERV’s.  When configuring the accessory terminal there are only two options when wiring to the terminal. It will be one-wire or two-wire and this will determine what terminals are indicated during the configuration process. It is important to understand if the accessory is going to share the same 24V source that is used to power the ecobee or if it will use a different 24V source.

During the troubleshooting procedures you’ll need to determine:

  • Are you using powered or non-powered Accessories? You may not know the difference, so the best way in this case to determine “is your humidifier or dehumidifier getting power from 120V”? There will be a 120V power cord attached to the unit. How did you wire the accessory wires? Was it powered unit but you configured the ecobee as non-powered or vice versa.




The main difference between 1-wire and 2-wire is that 2-wire is electrically isolated from the power source that is used to power the HVAC system and thermostat control. If the accessory is not getting activated ensure that the series circuit always terminates to the Common side of the 24V transformer.



Was this article helpful?

Have more questions? Submit a request