US Patent 7216016 Failure mode for HVAC system

A HVAC system provides a central control which detects failed stage(s); removes the failed stage(s) from the staging sequence used by the controller; and later checks the failed stage periodically to see if the failed stage has become functional so that the no properly operational stage is returned to a staging sequence. The central control detects the failed stages and/or components by direct communication with the failed stages and/or components and/or by monitoring a temperature of a controlled area to determine if any particular stage is operating properly.