Modified heat pump

Abstract

A modified heat pump ( 12 ) comprises a closed circuit around which a refrigerant fluid is circulated, a plenum chamber ( 13 ) and an auxiliary heat exchanger ( 16 ). The closed circuit has a compressor, a condenser, an expansion valve and an evaporator. The evaporator is located within the plenum chamber ( 13 ). The plenum chamber ( 13 ) also has an inlet ( 14 ) adapted to receive a fluid heat source medium and direct it over the evaporator, thereby to extract heat from said medium, and an outlet ( 15 ) adapted to receive cooled medium expelled from the plenum chamber ( 13 ). The auxiliary heat exchanger ( 16 ) is located between the inlet ( 14 ) and the evaporator, and is adapted to warm said medium prior to it passing over the evaporator.

1 . A heat pump comprising:
 a closed circuit around which a refrigerant fluid is circulated, said closed circuit having a compressor, a condenser, an expansion valve and an evaporator;   a plenum chamber having said evaporator located therewithin, an inlet adapted to receive a fluid heat source medium and direct it over the evaporator, thereby to extract heat from said fluid heat source medium, and an outlet adapted to receive cooled fluid heat source medium expelled from the plenum chamber; and   an auxiliary heat exchanger located between the inlet and the evaporator, and adapted to warm said fluid heat source medium prior to it passing over the evaporator.   
     
     
         2 . The heat pump of  claim 1 , wherein the auxiliary heat exchanger is driven by heat recovered from the condenser. 
     
     
         3 . The heat pump of  claim 1  or  claim 2 , comprising a damper adapted to direct the fluid heat source medium over the auxiliary heat exchanger only when the auxiliary heat exchanger has been activated. 
     
     
         4 . The heat pump of  claim 1 , further comprising a damper adapted to direct the fluid heat source medium over the auxiliary heat exchanger, only upon said fluid heat source medium's ambient temperature falling below a predetermined value. 
     
     
         5 . The heat pump of  claim 3 , further comprising thermostatic control means adapted to activate the damper upon the fluid heat source medium's ambient temperature falling below a predetermined value. 
     
     
         6 . The heat pump of  claim 1 , further comprising thermostatic control means adapted to activate the auxiliary heat exchanger upon the fluid heat source medium's ambient temperature falling below a predetermined value. 
     
     
         7 . The heat pump of  claim 6 , wherein the thermostatic control means includes a motorised valve adapted to deliver heated water to the auxiliary heat exchanger, upon activation. 
     
     
         8 . The heat pump of  claim 4 , wherein said predetermined value for the fluid heat source medium's ambient temperature is substantially 5° C. 
     
     
         9 . (canceled) 
     
     
         10 . (canceled) 
     
     
         11 . (canceled) 
     
     
         12 . The heat pump of  claim 1 , wherein the heat pump is an air source heat pump, the fluid heat source medium is air, and wherein:
 the plenum chamber has an air inlet adapted to receive indrawn air and direct said air over the evaporator, thereby to extract heat from said air, and an air outlet adapted to receive cooled air expelled from the plenum chamber; and   the auxiliary heat exchanger is located between the air inlet and the evaporator, and is adapted to warm said indrawn air prior to it passing over the evaporator.   
     
     
         13 . The heat pump of  claim 12 , further comprising a fan adapted to draw air into the plenum chamber through the air inlet, and out of the plenum chamber through the air outlet. 
     
     
         14 . The heat pump of  claim 12 , further comprising sound dampening means to enable said heat pump to be housed conveniently within a building to be heated. 
     
     
         15 . The heat pump of  claim 12 , further comprising a secondary air inlet adapted to receive re-circulated air from the interior of a building in which the heat pump is installed. 
     
     
         16 . The heat pump of  claim 15 , wherein the air inlet and the secondary air inlet are arranged such that said indrawn air and said re-circulated air are combined prior to passing over the evaporator. 
     
     
         17 . The heat pump of  claim 15 , wherein the air inlet and the secondary air inlet are arranged such that said indrawn air and said re-circulated air are combined prior to passing over the auxiliary heat exchanger. 
     
     
         18 . A heat pump installation comprising an air source heat pump as claimed in  12   10 , installed within a defined space of a building to be heated, said heat pump installation further comprising:
 an inlet vent adapted to permit a flow of air therethrough from said building's exterior, into said defined space;   an outlet vent adapted to permit a flow of cooled air from the heat pump to exit said building; and   an outlet air duct connecting the air outlet of the heat pump with the outlet vent.   
     
     
         19 . The heat pump installation of  claim 18 , wherein:
 the defined space is a loft; and   the inlet and outlet vents are roof tile vents.   
     
     
         20 . The heat pump installation of  claim 18 , further comprising an inlet air duct connecting the air inlet of the air source heat pump with the inlet vent. 
     
     
         21 . The heat pump installation of  claim 18 , comprising the air source heat pump further comprising a secondary air inlet adapted to receive re-circulated air from the interior of the building, said installation further comprising a secondary inlet vent adapted to permit a flow of re-circulated air therethrough from the interior of the building, into said defined space. 
     
     
         22 . The heat pump installation of  claim 21 , further comprising a secondary inlet air duct connecting the secondary air inlet of the air source heat pump with the secondary inlet vent. 
     
     
         23 . The heat pump of  claim 3 , further comprising thermostatic control means adapted to activate the damper upon the auxiliary heat exchanger's temperature reaching a predetermined value.