| 摘要 |
PURPOSE:To enable to defrost in accordance with the conditions of the ambient condition and prevent the heating efficiency from lowering by a method wherein the next forced heating operation time is determined in accordance with the time required for the recent defrosting and the previously derived defrosting time-heatong operation time characteristics. CONSTITUTION:At the start of heating operation, firstly, forced heating operation is performed for a certain time or, for example, for 60min and, after that, the temperature T0 of an outdoor heat exchanger sensed with a thermometer 1 is compared with the temperature T1 for necessitating defrosting set by a temperature setter 2. When the tempeature T0 is higher than the temperature T1, the forced heating operation is performed for another 60min. When the temperature T0 is lower than the temperature T1, a microcomputer 7 issues the controlling signal C in order to actuate a solenoid valve 6 so as to switch to cooling operation. The cooling operation is continued for 10min at the longest until the temperature T1 descends to the temperature T2 for switching to heating operation. At this time, the time required for defrosting is counted and the next forced heating operation time Th is determined in accordance with the previously memorized defrosting time-heating operation time characterstic by applying the counted time required for defrosting T as the new basis. |
