| 摘要 |
PURPOSE:To permit defrosting at timing suitable to the actual condition of heating operation, by a method wherein the conditions of defrosting operation, expected to be effected immediately after the present heating operation, are considered from the defrosting operation, effected immediately before the present heating operation, and the condition of the heating operation effected before the present operation. CONSTITUTION:A temperature difference accumulating means 3 operates and stores the cumulative value Sn of temperature differences by accumulating temperature differences DELTATn operated by a temperature difference operating means 1. A forecasting defrosting time operating means 4 operates the cumulative time (tu) of previous heating operation and a time (td) required for previous defrosting operation to operate a forecasting defrosting operation time (tdy) with respect to a heating operation time effected until present. An average heating capacity operating means 5 operates and stores an average heating capacity Qn by dividing the temperature difference cumulative value Sn by the sum of a heating operation time (t1) and the forecasting defrosting operation time (tdy). A comparing means 6 compares the average heating capacity Qn of present time with the average heating capacity Qn-1 of previous time: when the value of present time is smaller, a defrosting signal is outputted.
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