| 摘要 |
PURPOSE:To allow the defrosting which is appropriate under existing frosting conditions by respectively setting the space heating mode operation time and the defrosting mode operation time according to the atmospheric condition, and setting the defrosting completion temperature based on the frosting sensing temperature of outdoor heat exchanger. CONSTITUTION:A micro computer 9 has a means 10 for setting the space heating mode operation time and a means 11 for setting the defrosting time which receive the output from an atmospheric temperature sensor 6, a means 12 which senses the frosting by measuring the output from a pipe temperature sensor 7 for a certain time interval, and a means 13 which sets the pipe temperature at the time of defrosting completion. When the space heating mode operation is started, the heating mode operation time and defrosting mode operation time are set according to the atmospheric temperature which is measured at regular intervals. If the preset heating mode operation time is past, and the pipe temperature is less than the predetermined limit for a predetermined time duration, the defrosting operation is started. When the pipe temperature becomes higher than the preset defrosting completion temperature after the defrosting is started, the space heating mode operation is resumed. The heating operation is also resumed when the preset defrosting time is past even if the pipe temperature may not be above the set temperature yet.
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