Please use the following compatibility checkers prior to making your thermostat purchase. Click on the link for the brand of thermostat you are looking to purchase to view compatibility with your system. Open box returns will not be accepted due to system compatibility issues.
Google Nest: https://store.google.com/intl/en_us/widget/compatibility/thermostat/
ecobee: https://www.ecobee.com/en-us/compatibility/thermostat/
Honeywell Home: https://www.honeywellhome.com/us/en/thermostat-wiring-compatibility/
Emerson: https://webapps.copeland.com/resources/wire-picker.aspx