Heat pump type hot water supply apparatus

Abstract

A heat pump type hot water supply apparatus includes a heat-source side heat pump unit 2 for heating water, a hot water tank 1 for storing therein hot water heated by the heat-source side heat pump unit 2 , and a hot water supply heat exchanger 10 which is placed in the hot water tank 1 and in which water flows from lower side toward upper side of interior thereof. There is provided a difference between heat exchange performance of a lower-stage side portion 10 b and heat exchange performance of an upper-stage side portion 10 a of the hot water supply heat exchanger 10.

1 . A heat pump type hot water supply apparatus comprising:
 a heat-source side heat pump unit for heating water;   a hot water tank for storing therein hot water heated by the heat-source side heat pump unit; and   a hot water supply heat exchanger which is placed in the hot water tank and in which water flows from lower side toward upper side of interior thereof, wherein   there is provided a difference between heat exchange performance of a lower-stage side portion and heat exchange performance of an upper-stage side portion of the hot water supply heat exchanger.   
   
   
       2 . The heat pump type hot water supply apparatus as claimed in  claim 1 , further comprising:
 the heat-source side heat pump unit having a radiative heat exchanger for condensing a refrigerant to radiate heat derived from the refrigerant; and   a hot water supply unit including: the hot water tank in which water is stored; water circulation pipes which are communicated with bottom side and top side of the hot water tank and which allow water in the hot water tank to be circulated from the bottom side to the top side in a bypass state; an endothermic heat exchanger which is placed on way of the water circulation pipes and which is heat-absorbably coupled to the radiative heat exchanger of the heat-source side heat pump unit; and the hot water supply heat exchanger which is of an annular coil type and allows water to flow, from outside, in thereinto and out therefrom in a flow-through state, wherein   the water in the hot water tank is heated by the radiative heat exchanger of the heat-source side heat pump unit via the endothermic heat exchanger provided on the way of the water circulation pipes, while the water to be heated flowing within the hot water supply heat exchanger is heated by the water in the hot water tank.   
   
   
       3 . The heat pump type hot water supply apparatus as claimed in  claim 2 , wherein inner-surface machined tubes are used for annular-coil heat transfer tubes of either one of the lower-stage side portion or the upper-stage side portion of the hot water supply heat exchanger, whereby a heat transfer rate of heat-transfer-tube part of either one of the lower-stage side portion or the upper-stage side portion is set higher than a heat transfer rate of the other of the lower-stage side portion and the upper-stage side portion. 
   
   
       4 . The heat pump type hot water supply apparatus as claimed in  claim 2 , wherein an annular-coil heat transfer tube of either one of the lower-stage side portion or the upper-stage side portion of the hot water supply heat exchanger are set smaller in inner diameter than an annular-coil heat transfer tube of the other portion so that a flow velocity of water flowing through inside the heat transfer tube of the either one is enhanced, whereby a heat transfer rate of heat-transfer-tube part of the either one of the lower-stage side portion or the upper-stage side portion is improved over a heat transfer rate of the other of the lower-stage side portion and the upper-stage side portion. 
   
   
       5 . The heat pump type hot water supply apparatus as claimed in  claim 2 , wherein an annular-coil winding pitch of either one of the lower-stage side portion or the upper-stage side portion of the hot water supply heat exchanger is set smaller than an annular-coil winding pitch of the other portion, whereby an annular-coil heat transfer area of the either one of the lower-stage side portion or the upper-stage side portion is set larger than an annular-coil heat transfer area of the other of the lower-stage side portion and the upper-stage side portion. 
   
   
       6 . The heat pump type hot water supply apparatus as claimed in  claim 1 , wherein a lower part of the annular coil in the lower-stage side portion of the hot water supply heat exchanger gradually decreases in annular-coil outer diameter so as to be wound into a helical state. 
   
   
       7 . The heat pump type hot water supply apparatus as claimed in  claim 1 , wherein a lower part of the annular coil in the lower-stage side portion of the hot water supply heat exchanger gradually decreases in annular-coil outer diameter so as to be wound into a planar spiral state. 
   
   
       8 . The heat pump type hot water supply apparatus as claimed in  claim 1 , wherein heat exchange performance of the lower-stage side portion of the hot water supply heat exchanger is set higher than heat exchange performance of the upper-stage side portion.