Abstract: A combined environmental and refrigeration system for use in a supermarket or the like includes a plurality of environmental and refrigeration modules and controllable air flow dampers to provide selected air flow modes to a conditioned space. Each module includes a hot deck compartment having a fan and the condenser portion of a refrigeration system to heat an air flow through the hot deck compartment, and a cold deck compartment having the evaporator portion of an air conditioning system to cool the air supplied to the conditioned space. At least a portion of the condenser in one of the hot deck compartments is provided to sub-cool the refrigeration system working fluid.The various fans, evaporators, condensers, and dampers are controlled by suitable control means to provide a conditioned space dehumidification mode, and a plurality of conditioned space cooling and heating modes.

Abstract: A method and apparatus for initiating the defrost of refrigeration equipment on demand. A defrost clock which normally controls the conventional refrigeration and defrost modes of a refrigeration system includes an auxiliary switch to cease operation of the clock motor a predetermined time prior to normal defrost initiation. The defrost clock thus remains in the refrigeration mode until the demand defrost sensor switch, or an optional demand switch, initiates a defrost cycle of the refrigeration equipment. The closure of the demand defrost switch or the optional switches causes the defrost clock motor to run for a predetermined short period of time. The defrost clock switch subsequently closes slightly prior to initiation of a defrost to guarantee that the clock runs throughout the defrost mode. Thereafter, the defrost clock controls the length of the defrost and will terminate defrost upon a signal from a thermostat, or by a time signal, or a pressure signal.