Instantaneous hot water appliance

Abstract

An instantaneous hot water appliance uses three loops. The first loop is an open loop that receives source water. Heat is extracted from the source water by a heat pump. The heat is supplied to a utility liquid, such as water, that is circulated within the closed loop. The resulting cooled source water may be used for other purposes. Heat exchange between the utility water in the closed loop and a second open loop heats domestic hot water within the second open loop. Domestic hot water is available on demand, eliminating or reducing the need for domestic hot water storage tanks and storage of large quantities of domestic hot water. In the present invention, fluctuations in condenser water temperature are dampened internally by a compressor control system as described herein that may be supplemented by a condenser water buffer.

What is claimed: 
     
         1 . A water heating appliance, comprising:
 a first open water loop that receives source water and discharges cooled source water;   a closed loop that circulates a liquid within the closed loop;   a second open water loop that receives potable domestic water and discharges heated potable domestic water;   a heat pump that extracts heat from the source water and provides the heat to the liquid in the closed loop producing heated liquid in the closed loop and producing the cooled source water for discharge from the first open water loop;   a first compressor that regulates a temperature of the heated liquid in the closed loop;   a heat exchanger that transfers heat from the heated liquid in the closed loop to the domestic potable water in the second open water loop producing the heated potable domestic water.   
     
     
         2 . A water heating appliance as described in  claim 1 , further comprising a second compressor that regulates the temperature of the heated liquid in the closed loop. 
     
     
         3 . A water heating appliance as described in  claim 1 , further comprising a sensor that measures temperature of heated water available for discharge from the second open water loop and a controller that actuates the first compressor in response to the sensor. 
     
     
         4 . A water heating appliance as described in  claim 2 , further comprising a sensor that communicates with utility water exiting a condenser, and a controller, wherein the controller actuates the first compressor when the utility water exiting the condenser decreases to a first temperature and terminates actuation of the first compressor of the heat pump when the utility water exiting the condenser reaches a second temperature that is higher than the first temperature, and the controller actuates a second compressor of the heat pump when the utility water exiting the condenser decreases to a third temperature and terminates actuation of the second compressor of the heat pump when the utility water exiting the condenser reaches a fourth temperature. 
     
     
         5 . A water heating appliance as described in  claim 1 , the closed loop further comprising a temperature control loop that communicates with the heat exchanger, the temperature control loop comprising a three-way diverting valve wherein water enters a first port of the three way and the water flows from two ports of the three-way diverting valve proportionate to a flow required to control the temperature of the heated potable domestic water. 
     
     
         6 . A water heating appliance as described in  claim 1 , the first open water loop comprising a cooling loop that enables source water to circulate to a heat pump evaporator independently of external source water, the open water loop comprising a temperature controller that controls a position of a control valve causing source water to return to the first open water loop. 
     
     
         7 . A water heating appliance as described in  claim 1 , further comprising a hydraulic and thermal buffer positioned within the closed loop between the first compressor and the heat exchanger, the hydraulic and thermal buffer constructed and arranged to equalize a supply of the liquid to the heat pump. 
     
     
         8 . A water heating appliance as described in  claim 1 , wherein source water is received into the first open water loop from a building cooling system. 
     
     
         9 . A water heating appliance as described in  claim 1 , wherein source water is received into the first open water loop from the building cooling system and the cooled source water is discharged from the first open water loop into a building cooling system. 
     
     
         10 . A water heating appliance as described in  claim 1 , wherein source water is received into the first open water loop from the building cooling system and the cooled source water is discharged from the first open water loop into a building cooling system of a multi-family residential building. 
     
     
         11 . A water heating appliance as described in  claim 1 , wherein the liquid in the closed loop comprises water. 
     
     
         12 . A water heating appliance as described in  claim 1 , wherein the liquid in the closed loop comprises water and glycol. 
     
     
         13 . A water heating appliance as described in  claim 1 , wherein the heated potable domestic water is supplied to a multi-family residential building. 
     
     
         14 . A water heating appliance as described in  claim 1 , wherein the heat exchanger in the closed loop is a double-walled heat exchanger.