Guide on Ecobee Thermostats Compatibility

Guide on Ecobee Thermostats Compatibility

Ecobee thermostats are compatible with most 24-volt residential heating and cooling systems. These systems include gas, oil, electric, and dual-fuel systems.

Ecobee thermostat are not compatible with thermostats with high voltage labels (you can check this by switching off the power to the thermostat and removing the cover to expose the wires from the wall to the base. If unsure, please contact HVAC specialist):
110V, 120V, or 240V


Some older thermostats have separate O and B wires connected and a C connector (which may or may not have a wire). Unfortunately, ecobee thermostats are not compatible with these systems (see further below on this article on wire functions).

Some of the thermostats not compatible with ecobee include: Honeywell CT3500, CT3595, CT3600, T8775A (check this replacement), RTH2510, and RTH2410.

Based on the wires coming out of the wall to the base of your thermostat, various ecobee thermostats can work with your home unit. 

For example, if the wires from the wall connects to Rh, G, Y, and C (do not connect jumper wires on ecobee thermostats, they use internal jumper wires e.g. between Rh and Rc) ecobee3 lite should work for you.

Here are examples of the possible base labels on thermostats to which wires can be connected:


Good to note, wire labeled B goes into the O/B connector on your ecobee thermostat and is used to control the heat pump's reversing valve, which switches between heating and cooling modes (see image above on the wire color codes and its functions). 

However, on some thermostats, the wire labeled B is the Common (C) wire and it is important to identify if B is used as common wire in your old system so that you connect it appropriately on the ecobee thermostat.

If a common wire is inserted into any connector other than C, the fuse on your HVAC system can be damaged/blown when the system is powered on.  If you are unsure about a wire, we recommend booking a local HVAC specialist to install your ecobee thermostat.

Here is more information on general thermostat wiring:

For custom HVAC control solutions, feel free to contact our HVAC Specialists for assistance or learn more on our HVAC Controls website.
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