Method and system for heating auto-setback

An HVAC system comprising:

• a compressor configured to compress a refrigerant;
• an evaporator coil coupled to the compressor and configured to receive the refrigerant;
• a condenser coil coupled between the evaporator coil and the compressor,
• a controller comprising a central processing unit and memory, the controller configured to perform the following steps:
• predict a first predicted temperature of an enclosed space during an unoccupied time with the HVAC system off;
• determine if the first predicted temperature is less than a set-point temperature;
• responsive to a determination that the first predicted temperature is less than the set-point temperature, predict a second predicted temperature of the enclosed space if the HVAC system is operated for a first runtime;
• determine if the second predicted temperature is less than the set-point temperature;
• and
• responsive to a determination that the second predicted temperature is less than the set-point temperature, operate the HVAC system for the first runtime.

A method of operating an HVAC system using a controller, the method comprising:

• determining if an enclosed space of the HVAC system is unoccupied;
• responsive to a determination that the enclosed space is unoccupied, setting a heating demand to zero for an unoccupied time;
• predicting a first predicted temperature of the enclosed space during the unoccupied time with the HVAC system off;
• determining if the first predicted temperature is less than a set-point temperature;
• responsive to a determination that the first predicted temperature is less than the set-point temperature, predicting a second predicted temperature of the enclosed space if the HVAC system is operated for a first runtime;
• determining if the second predicted temperature is less than the set-point temperature;
• responsive to a determination that the second predicted temperature is less than the set-point temperature, operating the HVAC system for the first runtime;
• and
• responsive to a determination that the second predicted temperature is less than the set-point temperature, repeating, for an increased runtime, the step of predicting the second predicted temperature and the step of determining if the second predicted temperature is less than the set-point temperature.