Thermal store

Abstract

A thermal store system for a water heating system comprising a primary thermal store containing a primary volume of water adapted to be heated by a primary heating means, said primary thermal store being in thermal communication with a central heating supply flow and a central heating return flow, a secondary water heat exchanger in thermal communication with the primary volume of water, the secondary water heat exchanger having a water feed flow and a water outlet flow for supplying hot water, at least one of said central heating return flow and/or said water feed flow being in thermal communication with at least one further thermal store, upstream of said primary thermal store, said at least one further thermal store containing a medium adapted to be heated by at least one supplementary heating means.

1 . A thermal store system for a water heating system comprising a primary thermal store containing a primary volume of water adapted to be heated by a primary heating means, said primary thermal store being in thermal communication with a central heating supply flow and a central heating return flow, a secondary water heat exchanger in thermal communication with the primary volume of water, the secondary water heat exchanger having a water feed flow and a water outlet flow for supplying hot water, at least one of said central heating return flow and/or said water feed flow being in thermal communication with at least one further thermal store, upstream of said primary thermal store, said at least one further thermal store containing a medium adapted to be heated by at least one supplementary heating means. 
     
     
         2 . A system as claimed in  claim 1 , wherein both said central heating return flow and said water feed flow are in thermal communication with said at least one further thermal store whereby said central heating return flow and said water feed flow receive heat by thermal communication with said at least one further thermal store before entering into thermal communication with said primary thermal store. 
     
     
         3 . A system as claimed in  claim 1 , wherein the two or more further thermal stores are arranged such that the operating temperature of supplementary heating means of each further thermal store increases in the direction of flow of the central heating return flow from a relatively low temperature to a relatively high temperature to provide heat transfer between the central heating return flow, and/or the water feed flow, and the medium of each further thermal store in turn. 
     
     
         4 . A system as claimed in  claim 1 , wherein the primary heating means is powered by fossil fuel. 
     
     
         5 . A system as claimed in  claim 3 , wherein the primary thermal store is provided with a first heat exchange circuit adapted to receive heat from said primary heating means for heating the primary volume of water. 
     
     
         6 . A system as claimed in  claim 1 , wherein said primary volume of water is in fluid communication with said central heating supply flow and said central heating return flow whereby said primary volume of water forms part of a central heating circuit. 
     
     
         7 . A system as claimed in  claim 1 , wherein said at least one further thermal store is adapted to be heated by two or more supplementary heating means. 
     
     
         8 . A system as claimed in  claim 1 , wherein said primary thermal store is provided with one or more further water heat exchange circuits adapted to receive heat from one or more further sources of heat. 
     
     
         9 . A system as claimed in  claim 1 , wherein said at least one supplementary heating means comprises at least one of a heat pump, an electrical immersion heater, a solar energy collector, a biomass heat source, a fuel cell or any other available heat source. 
     
     
         10 . A system as claimed in  claim 1 , wherein two or more further thermal stores are provided, each further thermal store containing a medium to be heated by a respective supplementary heating means, said two or more further thermal stores being connected in series whereby the central heating return flow and/or the water feed flow is heated from a low temperature to a high temperature through heat exchange with the medium in each successive thermal store. 
     
     
         11 . A system as claimed in  claim 1 , wherein said medium contained in said at least one further thermal store comprises a secondary volume of water. 
     
     
         12 . A system as claimed in  claim 11 , wherein said further thermal store has substantially the same structure as the primary thermal store. 
     
     
         13 . A system as claimed in  claim 11 , wherein said further thermal store is provided with a heat exchange circuit adapted to receive heat from said supplementary heating means for heating the secondary volume of water. 
     
     
         14 . A system as claimed in  claim 11 , wherein said secondary volume of water is in fluid communication with said central heating supply flow and said central heating return flow whereby said secondary volume of water forms part of a central heating circuit. 
     
     
         15 . A system as claimed in  claim 14 , wherein said central heating return flow enters the further thermal store at or adjacent a lower region of the further thermal store and exits said further thermal store at or adjacent an upper region of the further thermal store. 
     
     
         16 . A system as claimed in  claim 15 , wherein a central heating circuit completing conduit is provided between said primary and further thermal stores providing fluid communication between an upper region of the further thermal store and a lower region of said primary thermal store. 
     
     
         17 . A system as claimed in  claim 16 , wherein said circuit completing conduit is provided with a non-return valve to prevent reverse flow between the primary and further thermal stores. 
     
     
         18 . A system as claimed in  claim 11 , wherein a flow communication is provided between said primary thermal store and said further thermal store, said flow communication being provided with a pump for selectively passing water between said primary and further thermal stores when the temperature of said primary volume of water is less than the temperature of any other connected volume of water. 
     
     
         19 . A system as claimed in  claim 11 , wherein the water supplied to said water feed means passes through a water heat exchanger in thermal communication with said secondary volume of water before entering said secondary heat exchanger of said primary thermal store. 
     
     
         20 . A system as claimed in  claim 19 , wherein said water heat exchanger comprises a first heat exchange coil provided in a lower region of the further thermal store and a second heat exchanger coil, connected downstream of said first heat exchange coil, provided in an upper region of the further thermal store, said first heat exchange coil generating a depletion zone in the lower region of the further thermal store. 
     
     
         21 . A system as claimed in  claim 1 , wherein said medium contained in said at least one further store comprises a material adapted to change between solid and liquid states at substantially the operating temperature of the supplementary heating means adapted to supply heat to said medium. 
     
     
         22 . A system as claimed in any of  claim 1 , wherein said medium contained in said at least one further store comprises a mixture or combination of materials adapted to change between solid and liquid states at different temperatures falling within a predetermined range of the operating temperature of the supplementary heating means adapted to supply heat to said medium. 
     
     
         23 . A system as claimed in  claim 21 , wherein two or more further thermal stores are provided, each further thermal store containing said medium, said two or more further thermal stores being connected in series whereby the central heating return flow is heated from a low temperature to a high temperature through heat exchange with the medium in each successive thermal store. 
     
     
         24 . A system as claimed in  claim 23 , wherein said central heating return flow and/or said water feed flow passes through a heat exchange circuit in each of said two or more further thermal stores in turn to receive heat from the medium contained in each subsequent further store before passing into said primary thermal store. 
     
     
         25 . A thermal store system for heating water, said system comprising a first and one or more further thermal stores, each thermal store containing a medium adapted to be heated by a heating means, the heating means of a first thermal store having an operating temperature generally higher than that of the heating means of the or each further thermal store; a flow path being provided through each thermal store from the last further thermal store to the first thermal store in turn whereby a flow of water to be heated passing along said flow path sequentially receives heat from each thermal store from a relatively low temperature to a relatively high temperature. 
     
     
         26 . A thermal store system for heating water, the system comprising a plurality of thermal stores, each thermal store having a charge circuit, in thermal communication with a respective heating means for heating a medium contained therein, and a discharge circuit for providing heat transfer between said medium and a fluid passing though said discharge circuit, whereby the discharge circuit of the thermal stores are connected in series such that a fluid flowing therethrough receives heat from each thermal store from a relatively low temperature to a relatively high temperature.