Heat pump defrost control.

摘要

An outdoor coil defrost control system for a reverse cycle refrigeration apparatus or heat pump comprises an outdoor air temperature sensor (30), a compressor operation signal generator (42) and a variable frequency oscillator (80) receiving the input signal indicative of the outdoor air temperature and generating an output signal the frequency of which varies as a non-linear function of the magnitude of the outdoor air temperature. A counter (C1 to CN) receives the output signal of the variable frequency oscillator. The refrigeration apparatus is placed into an outdoor coil defrost mode of operation upon the counter counting a preselected number of pulses