Abstract: In an embodiment, a method of testing a HVAC unit for a disconnected damper motor is provided. An outside air section of a damper assembly is closed and air is circulated through the unit. If a discharge air temperature is not substantially equal to a return air temperature, the damper motor is determined to be disconnected. Otherwise, an economizing function having a free cooling target temperature is started. An outside air temperature is compared to the free cooling target temperature. If the outside air temperature is less than the free cooling target temperature, the damper motor is determined to be disconnected if the damper motor has been commanded to fully open the outside air section. If the outside air temperature is not less than the free cooling target temperature, the damper motor is determined to be disconnected if a discharge air temperature is not substantially equal to an outside air temperature.

Abstract: In an embodiment, a method of testing a HVAC unit for a disconnected damper motor is provided. An outside air section of a damper assembly is closed and air is circulated through the unit. If a discharge air temperature is not substantially equal to a return air temperature, the damper motor is determined to be disconnected. Otherwise, an economizing function having a free cooling target temperature is started. An outside air temperature is compared to the free cooling target temperature. If the outside air temperature is less than the free cooling target temperature, the damper motor is determined to be disconnected if the damper motor has been commanded to fully open the outside air section. If the outside air temperature is not less than the free cooling target temperature, the damper motor is determined to be disconnected if a discharge air temperature is not substantially equal to an outside air temperature.

Abstract: A method of defrosting an energy recovery ventilator unit. The method comprises defrosting an energy recovery ventilator unit. The method comprises activating a defrost process of an enthalpy-exchange zone of the energy recovery ventilator unit when an air-flow blockage in the enthalpy-exchange zone coincides with a frost threshold in the ambient environment surrounding the energy recovery ventilator unit. The method also comprises terminating the defrost process when a heat transfer efficiency across the enthalpy-exchange zone returns to within 10 percent of a pre-frosting heat transfer efficiency wherein, the heat transfer efficiency is proportional to a temperature difference between an intake air zone of the energy recovery ventilator and a supply air zone of the energy recovery ventilator divided by a temperature difference between an return air zone of the energy recovery ventilator and the intake air zone.

Abstract: A method and apparatus for cooling a supply of air is provided. A unit controller receives a cooling demand signal. In response to the cooling demand signal, the unit controller adjusts an economizer according to an economizing function. The economizing function is configured to achieve an initial free cooling target temperature as a discharge air temperature. The unit controller receives an additional cooling demand signal. In response to the additional cooling demand signal, the unit controller reduces the free cooling target temperature. The unit controller adjusts the economizer according to the economizing function, with the economizing function configured to achieve the reduced free cooling target temperature as the discharge air temperature. Additionally in response to the additional cooling demand signal, the unit controller signals a unit to perform mechanical cooling on a supply of air received from the economizer.

Abstract: In an embodiment, a method of testing a HVAC unit for a disconnected damper motor is provided. An outside air section of a damper assembly is closed and air is circulated through the unit. If a discharge air temperature is not substantially equal to a return air temperature, the damper motor is determined to be disconnected. Otherwise, an economizing function having a free cooling target temperature is started. An outside air temperature is compared to the free cooling target temperature. If the outside air temperature is less than the free cooling target temperature, the damper motor is determined to be disconnected if the damper motor has been commanded to fully open the outside air section. If the outside air temperature is not less than the free cooling target temperature, the damper motor is determined to be disconnected if a discharge air temperature is not substantially equal to an outside air temperature.

Abstract: A method of defrosting an energy recovery ventilator unit. The method comprises activating a defrost process of an enthalpy-exchange zone of the energy recovery ventilator unit when an air-flow blockage in the enthalpy-exchange zone coincides with a frost threshold in the ambient environment surrounding the energy recovery ventilator unit. The method also comprises terminating the defrost process, including terminating the defrost process when an operating condition in the vicinity of the enthalpy-exchange zone substantially returns to a pre-frosting operating condition.