Apparatus for using cast-off heat to warm water from household water heater

Abstract

A retrofit heat transfer unit, including: a housing for the retrofit unit, including inlet and outlet ports for water and refrigerant; a water pump, in fluid communication with the water inlet port, the water pump adapted to pump water from a water source; a heat exchanger, in fluid communication with the water pump, the water outlet port, the refrigerant inlet port and the refrigerant outlet port; and a thermostat, configured to measure a temperature of the pumped water and activate the water pump when the water is below a predefined low temperature and cease to pump when water is above a predefined high temperature. The retrofit unit is also adapted to receive heated refrigerant fluid from an air conditioner and direct the refrigerant through the heat exchanger and direct the pumped water into the heat exchanger so that the refrigerant heats the water and the water cools the refrigerant.

What is claimed is: 
     
         1 . A retrofit heat transfer unit, comprising:
 (a) a housing for the retrofit unit, including: a water inlet port, a water outlet port, a refrigerant inlet port and a refrigerant outlet port;   (b) a water pump, in fluid communication with said water inlet port, said water pump adapted to pump water from a water source;   (c) a heat exchanger, in fluid communication with said water pump, said water outlet port, said refrigerant inlet port and said refrigerant outlet port; and   (d) a thermostat, configured to measure a temperature of said pumped water, pumped from said water source, such that said water pump is configured to pump water from said water source when said pumped water is below a predefined low temperature and cease to pump said water when said pumped water is above a predefined high temperature,   and wherein the retrofit unit is adapted to receive heated refrigerant fluid from an air conditioner at said refrigerant inlet port and direct said received heated refrigerant fluid through said heat exchanger and further adapted to direct said pumped water into said heat exchanger such that heat from said heated refrigerant fluid is transferred to said water, pumped into said heat exchanger, cooling said heated refrigerant fluid and heating said water, said heated water exiting said housing via said water outlet port.   
     
     
         2 . The heat transfer unit of  claim 1 , wherein said heat exchanger is a co-axial coil heat exchanger. 
     
     
         3 . The heat transfer unit of  claim 1 , wherein said heat exchanger is a plate heat exchanger. 
     
     
         4 . The heat transfer unit of  claim 1 , wherein said water source is a domestic water heater. 
     
     
         5 . The heat transfer unit of  claim 1 , wherein said air conditioner has a cooling function and a heating function for electively cooling and heating an indoor space. 
     
     
         6 . The heat transfer unit of  claim 5 , wherein the retrofit unit is configured to receive said heated refrigerant via said refrigerant inlet port from said air conditioner when said air conditioner is in a cooling state. 
     
     
         7 . The heat transfer unit of  claim 5 , wherein the retrofit unit is configured to receive said heated refrigerant via said refrigerant inlet port from said air conditioner when said air conditioner is in a heating state. 
     
     
         8 . The heat transfer unit of  claim 1 , wherein a differential between said predefined low temperature and said predefined high temperature is in a range between about 5° C. and 20° C. 
     
     
         9 . The heat transfer unit of  claim 1 , wherein said water source is a water supply line from an outdoor water provider and wherein the unit further comprises:
 (e) a valve configured to admit water from said supply line when heated water is being drawn from a water heater to a domestic water distribution system, wherein said water heater is operationally coupled to the retrofit unit via said water inlet port and said water outlet port.   
     
     
         10 . The heat transfer unit of  claim 1 , further comprising a switch for electively activating and deactivating said thermostat. 
     
     
         11 . The heat transfer unit of  claim 1 , further comprising:
 (e) a pressostat, configured to deactivate an outdoor cooling fan of said air conditioner when pressure in outdoor coils of said air conditioner is below a predefined compression pressure.   
     
     
         12 . The heat transfer unit of  claim 11 , further comprising a means for circumventing said pressostat. 
     
     
         13 . A method of increasing the combined efficiency of an air conditioner and a water heater tank, comprising the steps of:
 (a) interposing a retrofit heat exchange unit between an outdoor unit of the air conditioner and the water heater tank;   (b) cutting a refrigerant line between a compressor and a 3-way valve of the air conditioner;   (c) coupling said refrigerant line from said compressor to a refrigerant inlet port located on a housing of said retrofit unit;   (d) coupling said refrigerant line said 3-way valve to a refrigerant outlet port located on said housing;   (e) coupling the water heater tank to a water inlet port located on said housing, such that a water pump, disposed inside said housing and coupled to said water inlet port, when activated, is configured to draw water from the water heater tank; and   (f) coupling the water heater tank to a water outlet port located on said housing, such that heated water, when exiting a heat exchanger disposed in said housing and operationally coupled to said water outlet port, exits said water outlet port and enters the water heating tank, so that refrigerant from the air conditioner heats said water from said water heater tank, in said heat exchanger.   
     
     
         14 . The method of  claim 13 , further comprising the step of:
 (g) connecting a pressostat, disposed in said housing, to the air conditioner, for disconnecting a cooling fan of said outdoor unit when pressure in coils of said outdoor unit falls below a predetermined compression pressure.   
     
     
         15 . The method of  claim 14 , further comprising the step of:
 (h) installing in a control panel, operationally associated with said housing of said retrofit unit, a circumvention mechanism for circumventing said pressostat.   
     
     
         16 . The method of  claim 13 , further comprising the step of:
 (g) installing in a control panel operationally associated with said housing, a switch, for electively activating and deactivating said water pump.