US Patent 11867420 Backup control for HVAC system with headless thermostat

A method in a heating, ventilation, or air conditioning (HVAC) system includes retrieving a control input from a remote computing system via a cellular network responsive to determining that a connection to a local wireless network cannot be established and generating a control signal for HVAC equipment based on the control input or generating a control signal for HVAC equipment by executing a backup control algorithm responsive to determining that a connection to a local wireless network cannot be established.