Hvac controller with hvac system failure detection

A method of monitoring operation of an HVAC system, the HVAC system including one or more HVAC components that are controlled, at least in part, by an HVAC controller having a user interface with a display, a memory, a controller, and an I/O block for receiving one or more signals from the HVAC system and for providing one or more control signals to the HVAC system, the method comprising:

• the I/O block of the HVAC controller repeatedly receiving one or more signals from the HVAC system that are related to a current performance level of the HVAC system;
• the controller of the HVAC controller determining if the current performance level of the HVAC system falls below a minimum performance level for at least a first predetermined amount of time;
• and
• the controller of the HVAC controller displaying an alert on the display of the HVAC controller if the controller determines that the current performance level has fallen below the minimum performance level for at least the first predetermined amount of time.

An HVAC controller configured to control one or more components of an HVAC system, the HVAC controller comprising:

• a user interface including a display;
• a memory;
• an I/O block for receiving one or more signals from the HVAC system and for providing one or more control signals to the HVAC system;
• a controller coupled to the memory, the user interface and the I/O block, the controller configured to:
• monitor one or more signals received via the I/O block that are related to a current delta T of the HVAC system;
• determine if the current delta T of the HVAC system falls below a minimum delta T limit for at least a first predetermined amount of time during a single cycle of the HVAC system;
• display an alert on the display of the HVAC controller if the controller determines that the current delta T of the HVAC system falls below a minimum delta T limit for at least the first predetermined amount of time;
• and
• remove the alert from the display of the HVAC controller if the current delta T subsequently rises and remains above the minimum delta T limit for at least a second predetermined amount of time.