Control system and method for multi-stage heating and cooling system with minimum on time and off time

摘要

A system and method are provided for activating and deactivating heating or cooling stages of a heating, ventilating, and air conditioning (HVAC) unit, which includes activating a heating or cooling stage of the HVAC unit based on a determined need for heating or cooling. A monitored temperature is compared with a first temperature setpoint and a monitored on-time of the heating or cooling stage is compared with a first time period setpoint. The heating or cooling stage is deactivated based on the comparison of the monitored temperature with the first temperature setpoint, when the monitored on-time is greater than the first time period setpoint. The monitored temperature is then compared with a second temperature setpoint. The heating or cooling stage is reactivated based on a comparison of the monitored temperature with the second temperature setpoint, when a monitored off-time is greater than the second time period setpoint.

主权项

1. A method comprising:
determining, with an HVAC control module of an HVAC unit having a first cooling stage and at least one additional cooling stage, a need for cooling of a space to be cooled based on a comparison of an indoor temperature of the space to be cooled with an indoor temperature setpoint; activating, with the HVAC control module, the first cooling stage and the at least one additional cooling stage of the HVAC unit based on the determined need for cooling; monitoring, with the HVAC control module, a monitored temperature of the HVAC unit corresponding to one of a supply air temperature of air exiting the HVAC unit and a return air temperature of air entering the HVAC unit; monitoring, with the HVAC control module, an on-time of the first cooling stage, the on-time being a time elapsed since activation of the first cooling stage; comparing, with the HVAC control module, the monitored temperature with an off-temperature setpoint and the monitored on-time with a minimum on-time period setpoint; deactivating, with the HVAC control module, the first cooling stage when the monitored temperature is less than the off-temperature setpoint and the monitored on-time is greater than the minimum on-time period setpoint; monitoring, with the HVAC control module, an off-time of the first cooling stage, the off-time being a time elapsed since deactivation of the first cooling stage; comparing, with the HVAC control module, the monitored temperature with an on-temperature setpoint, the on-temperature setpoint being greater than the off-temperature setpoint; comparing, with the HVAC control module, the monitored off-time with a minimum off-time period setpoint; reactivating, with the HVAC control module, the first cooling stage when the monitored temperature is greater than the on-temperature setpoint and the monitored off-time is greater than the minimum off-time period setpoint; operating the at least one additional cooling stage throughout when the first cooling stage is activated, deactivated, and reactivated; and modifying, with the HVAC control module, at least one of the off-temperature setpoint, the on-temperature setpoint, the minimum on-time period setpoint, and the minimum off-time period setpoint; evaluating performance of the HVAC unit, with the HVAC control module, after modification of the at least one of the off-temperature setpoint, the on-temperature setpoint, the minimum on-time period setpoint, and the minimum off-time period setpoint; and determining, with the HVAC control module, whether to further modify the at least one of the off-temperature setpoint, the on-temperature setpoint, the minimum on-time period setpoint, and the minimum off-time period setpoint based on the evaluation; wherein the at least one additional cooling stage has corresponding on-temperature and off-temperature setpoints that are different from the respective on-temperature and off-temperature setpoints of the first cooling stage.