system for controlling the formation of frost on cold surfaces

摘要

Frost control apparatus is disclosed for a temperature conditioning system such as a heat pump or the like, wherein a compressor circulates a volatile fluid through the closed system. Frost-buildup on the indoor and outdoor coils of the system is controlled by means of respective defrost cycles which occur in accordance with the conditions sensed by temperature sensing elements positioned at various points in the system. The defrost cycle for the indoor coil is maintained throughout a predetermined temperature range of ambient indoor air. The defrost cycle for the outdoor coil is initiated as a function of the differential between the temperature of the outdoor coil and that of ambient outdoor air and it varies in magnitude as a function of ambient outdoor air temperature. The termination of the outdoor coil defrost cycle is determined by a sensed temperature condition.