Heat pump system defrost control

摘要

An outdoor coil defrost control system for a reverse cycle refrigeration system comprising outdoor air temperature sensing means, means for producing an output signal indicative of the operation of the refrigeration compression means, and a special controller means having operative connections to the temperature sensing means and compression sensing means and comprising in part (a) a special variable frequency oscillator having an input indicative of the outdoor air temperature and an output signal the frequency of which varies as a non-linear function of the magnitude of the outdoor air temperature, (b) a counter means having an input connected to receive the output signal of the variable frequency oscillator, and (c) means for placing said refrigeration system into an outdoor coil defrost mode of operation upon the counter means counting a preselected number of counts or pulses.