Abstract: A water source heat pump system having a plurality of zone air conditioning units, each unit adapted for selectively heating or cooling a zone independent of other units, each air conditioning unit having an air conditioner coil, a heat exchanger of the type having a water contact coil disposed within a housing, a refrigerant compressor, and refrigerant control means operable to selectively cause the air conditioner coil to act as a refrigerant evaporator or condenser and the water contact coil heat exchanger to act as a refrigerant condenser or evaporator, the water contact coil heat exchanger utilizing thermostat control means to control the operation of the air conditioning unit so as to prevent freezing of water in the water contact coil heat exchanger.

Abstract: A multi-zone heating-cooling system having a plurality of reversible cycle air heating and cooling units connected to a closed loop water circulation circuit, and at least one ventilating air tempering coil in liquid flow communication with the water flowing in the closed loop water circulation circuit and in heat exchange relationship with a stream of outdoor air such as might be used for ventilation.