Abstract: Apparatus for controlling the temperature and humidity of air to be conditioned are disclosed. A fan coil unit incorporates a heat exchanger and a bypass area. The bypass area includes a damper assembly for apportioning the air flow between the bypass area and the heat exchanger such that humidity control of the air flowing therethrough may be obtained.

Abstract: Apparatus and method are disclosed for providing a relatively constant temperature level flow of discharge air from a reverse cycle air conditioning system. Air temperature of the air being discharged from the indoor heat exchanger of the refrigeration circuit is measured and used to control indoor fan speed to maintain the supply air temperature to the enclosure at a relatively constant temperature level. A secondary zone may be provided for receiving conditioned air from the indoor heat exchanger. A damper regulated in response to the leaving air temperature from the indoor heat exchanger is used to control the volume flow rate to the secondary zone such that as the indoor fan speed is decreased the damper decreases the volume flow rate to the secondary zone while maintaining a constant volume flow rate to the primary zone. An outdoor thermostat is provided for operating the indoor fan at normal speeds when the ambient temperature is within a predetermined range.

Abstract: A control circuit for a combination furnace and heat pump wherein a temperature dependent relay is connected to a thermostat such that the heat pump is operated to supply heat to an enclosure when the outdoor temperature is above a predetermined level and the furnace is operated to supply heat to the enclosure when the outdoor temperature is below a predetermined level. To defrost the outdoor coil of the heat pump the furnace is operated to supply heat to the indoor coil of the heat pump and a reversing valve relay is energized whereby the heat pump is operated in a reverse direction to supply heat to the outdoor coil for defrost.