Abstract: A thermal zone demand controlled air conditioning fan coil unit using dual cascade arranged heat pumps, chilled water, or a combination of chilled water and hot water, with or without back up electric resistance heat strips, and having an air circulation system for circulating air to and from a plurality of thermal zones and including a conditioned air chamber having first and second heat exchange refrigerant coils or direct or reversed cycle water coils being connected in refrigerant circulating relation respectively with the heat pumps, chilled water coil. A plurality of thermal zone blowers conduct conditioned air from the conditioned air chamber to respective thermal zones of a building space. Electronic controller circuitry of the system is coupled for thermal demand control of the heat pumps and the thermal zone blowers for operation of the first heat pump during average thermal load and for operation of both heat pumps during greater thermal load.

Abstract: A thermal zone demand controlled air conditioning fan coil unit using dual cascade arranged heat pumps, chilled water, or a combination of chilled water and hot water, with or without back up electric resistance heat strips, and having an air circulation system for circulating air to and from a plurality of thermal zones and including a conditioned air chamber having first and second heat exchange refrigerant coils or direct or reversed cycle water coils being connected in refrigerant circulating relation respectively with the heat pumps, chilled water coil A plurality of thermal zone blowers conduct conditioned air from the conditioned air chamber to respective thermal zones of a building space. Electronic controller circuitry of the system is coupled for thermal demand control of the heat pumps and the thermal zone blowers for operation of the first heat pump during average thermal load and for operation of both heat pumps during greater thermal load.