Backup control for HVAC system

An HVAC system comprising:

• an HVAC component having an HVAC controller;
• a remotely located wireless thermostat;
• an equipment interface module in wireless communication with the wireless thermostat and in wired communication with the HVAC controller, the equipment interface module is configured to provide instructions to the HVAC controller in accordance with and in response to signals received from the wireless thermostat;
• and
• wherein the equipment interface module is also configured to provide instructions to the HVAC controller without input from the thermostat if the equipment interface module loses communication with the wireless thermostat.

A method of operating an HVAC system having an HVAC component and an HVAC controller, an equipment interface module in wired communication with the HVAC component, a wireless thermostat in wireless communication with the equipment interface module, and a sensor in communication with the equipment interface module, the method comprising:

• controlling the HVAC component using the equipment interface module in accordance with signals provided by the wireless thermostat;
• determining if transmission of valid signals between the wireless thermostat and the equipment interface module has failed;
• and
• if it is determined that transmission of valid signals between the wireless thermostat and the equipment interface module has failed, controlling the HVAC component using the equipment interface module and the sensor until it is determined that transmission of valid signals between the wireless thermostat and the equipment interface module has been reestablished.