PURPOSE: To early start space heating and to perform defrosting operation without fail by radiating heat by means of a condenser without heat accumulation by use of a circuit for space heating only at the time of start of the space heating.
CONSTITUTION: A controller 18 so operates by a detection signal from a temperature detector 17 at the time of start of space heating as to close first, second, fourth switching valves 8, 9, 11, to open third, fifth switching valves 10, 15, to pass refrigerant from a condenser 2 to a second pressure reducing unit 3a, through the fifth valve 15 to an evaporator 4, further through the valve 10 to a compressor, to radiate heat only by the condenser 2 by bypassing a heat accumulation tank, and to respond to necessary space heating load at the side of the condenser 2. When the air temperature in a room of the condenser 2 side is raised to become a set temperature or higher, the controller 18 opens the valve 8 by a detection signal of a temperature detector 16, closes the valve 15, stops heat exchanging of the condenser 2, radiates heat to heat accumulation material 7 in a heat accumulation tank 6, and starts heat accumulation.
NAGATOMO HIDEAKI
SAKUMA KIYOSHI
TANIMURA YOSHIAKI
