Apparatus for capturing heat from a stove

Abstract

Apparatus for capturing heat from a stove to enable it to be transferred to a central heating system is disclosed. The apparatus comprises an air-water heat exchanger, the heat exchanger having an air side and a water side and being operative to transfer heat between air on the air side and water flowing in channels in the water side. The apparatus includes an air duct through which air heated by a stove can pass by convection to contact the air side of the heat exchanger and control means operable to control the amount of air flowing to the heat exchanger. The control means may include a fan that can be operated to direct the flow of air to the heat exchanger.

1 . A stove that incorporates a heat capturing apparatus for capturing heat from outer surfaces of the stove, the heat capturing apparatus comprising an air-water heat exchanger, the heat exchanger having an air side and a water side and being operative to transfer heat between air on the air side and water flowing in channels in the water side, characterised by the heat capturing apparatus including an air duct through which air heated by the stove can pass, and an enclosure surrounding the stove, said enclosure forming a chamber that partially surrounds the stove, the duct being connected to the enclosure, and control means operable to control the flow of air within the heat capturing apparatus by the operation of a fan; wherein in a first mode, the control means allows air to flow from the air duct to the chamber, then to a space surrounding the stove at least partly by natural convection and in a second mode, the control means induces air to flow from said chamber to the air duct, then to the air side of the heat exchanger, such that air within the duct flows in opposite directions in the first and second modes. 
     
     
         2 . A stove according to  claim 1  in which, in the first mode, air flows generally upward within the air duct. 
     
     
         3 . A stove according to  claim 1  in which the control means includes a fan that is operable to induce a flow of air in the heat capturing apparatus during operation in the second mode. 
     
     
         4 . A stove according to  claim 3  in which the fan is operable to draw air from a space surrounding the stove into the air duct for heating by the stove and then to the heat exchanger. 
     
     
         5 . A stove according to  claim 3  in which, when the fan is not operating, air can be drawn from a space surrounding the stove for heating by the stove, and subsequently returned to the space surrounding the stove by natural convection. 
     
     
         6 . A stove according to  claim 3  in which the state of the control means is primarily determined by whether or not the fan is running 
     
     
         7 . A stove according to  claim 1  that further includes a bypass means that allows air to flow through the duct to receive air transferred from the stove without passing through the heat exchanger in the first mode. 
     
     
         8 . A stove according to  claim 7  in which the bypass means includes a closable opening to surrounding air in the duct between the stove and the heat exchanger. 
     
     
         9 . A stove according to  claim 1  in which the air duct includes a plate, a first portion of the air duct being defined as a chamber that is formed between the plate and a heating surface of a stove. 
     
     
         10 . A stove according to  claim 1  in which the air duct has a second portion that connects the lower part of the first portion of the air duct to the air side of the heat exchanger. 
     
     
         11 . A stove according to  claim 1  in which the air duct causes air to flow over one or more external heating surfaces of the stove. 
     
     
         12 . A stove according to  claim 1  in which the apparatus for capturing heat further includes an outer cover that substantially completely encloses the enclosure to create a second air duct between itself and the enclosure. 
     
     
         13 . A stove according to  claim 12  in which air can be caused to flow in the second air duct by natural convection to reduce an outer casing temperature of the heat capturing apparatus. 
     
     
         14 . A stove according to  claim 1  in which the control means is fail-safe such that it diverts air from the heat exchanger in the event of there being insufficient flow of water within its water side. 
     
     
         15 . A heating installation that includes a stove according to  claim 1  and a central heating system that includes a pumped water circulation circuit that operates to transport heat from a boiler to one or more radiators, the water side of the heat exchanger being connected to the circulation circuit such that water from the circulation circuit is caused to flow through the heat exchanger while the pump of the circulation circuit is operational. 
     
     
         16 . A heating installation according to  claim 15  in which the control means operates to minimise the flow of heated air from the stove to the heat exchanger when the pump of the circulation system is not operational.