Water heating system

Abstract

Disclosed is a water heating system with a hot water storage tank having a first port located in a lower region of the tank and a second port located in an upper region of the tank; a water flow pathway extending from the first port through a heating chamber to the second port; electrical heating means (for example a heating element) arranged to heat water within the heating chamber, when required, so that water within the water heating system will circulate from the first port to the second port through the heating chamber, by convection, when water is not drawn from the water heating system; a water supply outlet communicating with the water flow pathway intermediate the heating chamber and the second port; and a check valve arranged to restrict the flow of water out of the hot water storage tank by way of the second port.

1 . A water heating system comprising: a hot water storage tank having a first port located in a lower region of the tank and a second port located in an upper region of the tank; a water flow pathway extending from the first port through a heating chamber to the second port; electrical heating means arranged to heat water within the heating chamber, when required, so that water within the water heating system will circulate from the first port to the second port through the heating chamber, by convection, when water is not drawn from the water heating system; a water supply outlet communicating with the water flow pathway intermediate the heating chamber and the second port; and a check valve arranged to restrict the flow of water out of the hot water storage tank by way of the second port when water is drawn from the water heating system through the water supply outlet. 
     
     
         2 . A water heating system according to  claim 1 , wherein the water flow pathway is located at least partially within the hot water storage tank. 
     
     
         3 . A water heating system according to  claim 1 , wherein the water flow pathway extends through a conduit including the electrical heating element and external to the hot water storage tank. 
     
     
         4 . A water heating system according to  claim 1 , wherein the check valve is located at the second port. 
     
     
         5 . A water heating system according to  claim 1 , wherein the check valve is operable between an open position, in which water is permitted to flow within the water flow pathway between the first port and the second port, and a closed position, in which the flow of water out of the hot water storage tank by way of the second port is restricted, responsive to a pressure differential across the check valve. 
     
     
         6 . A water heating system according to  claim 1 , wherein the check valve comprises a moveable member, moveable between a closed position in which the moveable member forms a cooperative fit with an aperture in the water flow pathway and an open position. 
     
     
         7 . A water heating system according to  claim 6 , wherein the moveable member comprises at least one aperture. 
     
     
         8 . A water heating system according to  claim 1 , wherein the electrical heating means comprises an elongate U-shaped heating element. 
     
     
         9 . A water heating system according to  claim 1 , wherein the electrical heating means comprises a plurality of heating elements, disposed in a generally circularly symmetric arrangement around the periphery of the interior of the heating chamber. 
     
     
         10 . A water heating system according to  claim 1 , wherein the heating chamber further comprises a space filling member. 
     
     
         11 . A water heating system according to  claim 10 , wherein the space filling member is positioned within the elongate loops of one or more heating elements. 
     
     
         12 . A water heating system according to  claim 11 , wherein the space filling member is generally cylindrical or prismatic, and positioned between the loops of a plurality of heating elements arranged, within a generally cylindrical heating chamber and wherein the water flow pathway within the heating chamber is generally annular. 
     
     
         13 . A water heating system according to  claim 1  comprising an inlet means, operable to admit a diffuse flow of unheated water into a lower region of the hot water storage tank. 
     
     
         14 . A water heating system according to  claim 13 , wherein inlet means comprises at least one perforated pipe. 
     
     
         15 . A water heating system according to  claim 13 , wherein the inlet means comprises mesh or other open pored material. 
     
     
         16 . A water heating system according  claim 1 , wherein the cross sectional area of the first port is less than the cross sectional area of the water flow pathway adjacent to the first port. 
     
     
         17 . A water heating system according to  claim 16 , wherein the cross sectional area of the first port is less than the cross sectional area of the water flow pathway in the heating chamber. 
     
     
         18 . A water heating system according to  claim 16 , wherein the cross sectional area of the first port is less than 15% of the cross sectional area of the water flow pathway adjacent the first port. 
     
     
         19 . A water heating system according to  claim 1 , having a first mode for heating water during circulation from the first port to the second port through the heating chamber, by convection, while water is not drawn from the water heating system and a second, higher power, mode for heating water when water is drawn from the water heating system through the water supply outlet. 
     
     
         20 . A domestic water heating system according to  claim 1 . 
     
     
         21 . A potable water heating system according to  claim 1 . 
     
     
         22 . A water heating system comprising: a hot water storage tank having a first port located in a lower region of the tank and a second port located in an upper region of the tank; a water flow pathway extending from the first port through a heating chamber to the second port; electrical heating means arranged to heat water within the heating chamber, when required, so that water within the water heating system will circulate from the first port to the second port through the heating chamber, by convection, when water is not drawn from the water heating system; and a water supply outlet communicating with the water flow pathway intermediate the heating chamber and the second port; wherein the water heating system has a first mode for heating water during circulation from the first port to the second port through the heating chamber, by convection, while water is not drawn from the water heating system and a second, higher power, mode for heating water when water is drawn from the water heating system through the water supply outlet. 
     
     
         23 . A water heating system according to  claim 22 , wherein the power output by the electrical heating means in the second mode is at least 150%, of the power output by the electrical heating means in the first mode. 
     
     
         24 . A water heating system according to  claim 22 , wherein the electrical heating means comprises one or more electrical heating elements which are used to heat water in the second mode, but not in the first mode. 
     
     
         25 . A water heating system according to  claim 22 , wherein the water heating system comprises more than one heating chamber. 
     
     
         26 . A water heating system according to  claim 25 , wherein the more than one heating chamber comprises a first heating chamber and a supplementary heating chamber, each connected by way of a conduit to the second port and the water supply outlet but connected to separate first ports, each of which is located in a lower region of the tank, and wherein water is heated in the supplementary heating chamber, by one or more electrical heating elements, in the second mode, but not the first mode. 
     
     
         27 . A water heating system according to  claim 22 , wherein the water heating system comprises a sensor for determining whether water is being drawn from the water heating system through the water supply output and is operable to switch automatically between the first and second mode depending on whether water is drawn from the water heating system through the water supply outlet, as determined by the sensor. 
     
     
         28 . A water heating system according to  claim 22 , wherein a check valve is arranged to restrict the flow of water out of the hot water storage tank by way of the second port when water is drawn from the water heating system through the water supply outlet. 
     
     
         29 . A water heating system according to  claim 19  further comprising a supplementary heating chamber in which water is heated in the second mode, but not the first mode. 
     
     
         30 . A water heating system according to  claim 19  further comprising a sensor for determining whether water is being drawn from the water heating system through the water supply output and wherein the system is operable to switch from the first mode to the second mode responsive to the detection of water flow by the sensor.