IE20040804A1 - Improvements in and relating to stoves - Google Patents

Abstract

A heat-storage stove comprising a thermally insulated shell containing one or more heating compartments 8, 9 in thermal contact with a system of ducts in communication with a chamber 6 which serves as a heat source. The chamber 6 is equipped with an electric heating assembly 1 comprising one or more resistance heating elements 2. The element(s) 2 are carried by a refractory armature 3 and arranged so that air can freely circulate between the element(s) 2 and the armature 3. <Figure 6>

Description

This invention relates to heat-storage stoves such as are used for cooking and/or for water heating, central heating, and similar domestic purposes.

Such cooking stoves are well known per se and examples thereof have been available on the market for many years under the trade names AGA™ and RAYBURN™, and they typically comprise a thermally insulated shell containing one or more cooking plates and one or more cooking compartments in thermal contact with a system of ducts communicating with a combustion chamber which serves as heat source. The combustion chamber is fed with a solid fuel, or, and more commonly nowadays, with fuels such as kerosene, natural gas or propane. Electrically heated stoves are also known.

It is an object of this invention to provide means whereby a fuel powered heat-storage stove may be converted to electric power.

According to this invention, there is provided a heat-storage stove 15 comprising a thermally insulated shell containing one or more heating compartments in thermal contact with a system of ducts communicating with a chamber which serves as heat source, wherein such chamber is equipped with an electric heating assembly comprising one or more resistance heating elements carried by a refractory armature and arranged so that air can freely circulate between the elements and the armature.

The invention also provides a method of converting a heat-storage stove comprising a thermally insulated shell containing one or more heating compartments in thermal contact with a system of ducts communicating with a combustion chamber which serves as heat source, wherein any burner is removed from such combustion chamber and such chamber is IITCt 7OPEH TO PUBLIC INSPECTIOH UNDER SECTION 28 AND RULE 23 JHL Ho.-LXL...

IE 04 08 04 then equipped with an electric heating assembly comprising one or more resistance heating elements carried by a refractory armature and arranged so that air can freely circulate between the elements and the armature.

In order that the heating element(s) may be powered from an ordinary domestic electric power supply, some preferred embodiments provide that the heating element be rated at less than 13 amp. We have found that a 2.5kW (10.9 amp at 230 volts) heater yields an ample heat output for most domestic cooking purposes.

To promote air circulation within the heating assembly, it is preferred that the armature be cruciform in cross section. Such an armature may be easily assembled from a pair of generally similar plates having slots extending half the length of the plate and with a width substantially equal to the thickness of the plate. The armature may be formed of an aluminium silicate material.

In order to promote secure retention of the heating element(s), it is preferred that the armature should be provided with holes through which such element(s) lead.

Advantageously, said heating assembly includes a stand for the armature which stand comprises a refractory top plate, having holes for the updraught of air between the heating element(s) and the armature, carried on supports allowing the inflow of air to beneath that top plate. The top plate is suitably of a ceramic material. The stand has a height typically of 60mm or more. An Aga™ heat storage stove with an air duct inlet opening at the base of the combustion chamber has the inlet typically of a diameter of 60 mm or more. A stand of such a height in such a stove promotes an efficient air recirculation pattern within the stove. >E 0 4Q804 In many cookers of the type with which the invention is concerned the heat source chamber is surmounted by a barrel which is in turn topped with a hot plate for cooking, the heat source chamber and barrel being located adjacent top and bottom ovens. In preferred embodiments of the invention, the heating assembly projects into such barrel, for example by between 60 and 160 mm. This promotes good air circulation within the stove, and also helps to achieve a good temperature balance between the top (hot) oven and the bottom oven.

A preferred embodiments of the invention will now be described with reference to the accompanying diagrammatic drawings in which: Figures 1 and 2 are respectively elevations of two parts of an armature of a heating assembly; Figures 3 and 4 are respectively a side elevation and a plan view of the heating assembly; and Figure 5 is a plan view of a stand of a heating assembly: Figure 6 is a cut away view of a stove incorporating the heating assembly.

As shown in Figures 1 to 4, an electric heating assembly 1 comprises a resistance heating element 2 carried by a refractory armature 3 and arranged so that air can freely circulate between the element 2 and the armature 3.

In order that the heating element may be powered from an ordinary domestic electric power supply, some preferred embodiments provide that the heating element be rated at less than 13 amp. We have found that a 2.5kW (10.9 amp at 230 volts) heater yields an ample heat output for most domestic cooking purposes.

,E 0 4 0 8 0 4 The armature 3 is cruciform in cross section. The armature is assembled from a pair of generally similar plates 30, 31 having slots 34 extending half the length of each plate, the slot of one plate being fitted over and accommodating the other plate. The slots 34 have a width substantially equal to the thickness of the plates. The armature may be formed of an aluminium silicate material.

In order to promote secure retention of the heating element 2, the armature 3 is provided with holes 32 through which such element leads. The armature 3 also includes holes 33 for locating lead-in wires 4 supplying current to the heating element 2.

The heating assembly 1 includes a stand 5 for the armature 3 which stand comprises a refractory top plate 51, having holes 52 (Figure 5) for the updraught of air between the heating element 2 and the armature 3, carried on supports 53 allowing the inflow of air to beneath that top plate 51. The top plate 51 is suitably of a ceramic material.

Figure 6 shows a cut-away section of the internal parts of a standard Aga™ stove having a body designed to allow the installation of gas or oil burners or to allow for combustion of solid fuel in a combustion chamber 6 and a barrel 7. The stove is provided with a top oven 8 and a bottom oven 9. Further ovens may be provided as desired. Air constantly recirculates through the stove by convection. Air heated in the combustion chamber 6 rises through a barrel 7 to heat the underside of a first hot plate (not shown) also located above that chamber and then across beneath a second hot plate (not shown) located above the ovens 8, 9 to pass through a flue 10 above the top oven 8 to an air circulation box 11 and down a return flue 12 to the combustion chamber 6. 0 4 As illustrated, instead of having a gas or oil burner or being arranged for solid fuel combustion, an electric heating assembly 1, such as has been described with reference to Figures 1 to 5, is installed in the stove. The heating assembly 1 substantially fills an opening 13 at the base of the barrel 9, and extends into the barrel 9 by between 60 and 160 mm. The plates from which the armature is formed may for example measure 250 x 175 mm. It is desirable that the top of the heating element should be at least as high as the bottom of the top oven 8.

The return flue 12 terminates in a combustion chamber air inlet 14 located at the base of the combustion chamber 6. The heating element 2 and armature 3 of the heating assembly 4 are supported above the level of that return inlet 14 by the use of the stand 5. As shown, the top plate 51 of the stand 5 occupies substantially the full plan area of the combustion chamber with the result that recirculating air is substantially constrained to flow through the holes 52 in that top plate and thus up between the plates 30, 31 of the armature 3 and the heating element 2. This promotes an efficient transfer of heat energy to that air.

A standard gas- or oil-fired or solid fuel Aga™ stove with an air duct inlet opening 14 has the opening typically of a diameter of 60 mm or more. A stand 5 having a height comparable to or slightly more than the diameter of the opening used in such a stove promotes an efficient air recirculation pattern within the stove.

The heat-storage stove shown in Figure 6 is made substantially entirely of cast iron - the ovens 8, 9, hot plates, barrel 7 and walls of the ducts are made of cast iron. Advantageously, heat is transferred to the cast iron from the heating element 2 and released continuously from all surfaces of the ovens. The ovens remain heated even when they are not being used so that they are always ready for use. Only a small amount of energy is then ,Ε ο 4 0 g ο 4 needed to quickly bring an oven up to a required cooking temperature. Depending upon the position of a particular oven or heat plate along the system of ducts, each will have a different temperature and thus a different cooking characteristic/use.

A thermostatic control is used to maintain a consistent, desired temperature over time.

An outer insulating casing surrounds the ovens and other components of the stove so that the resistance heating element(s) is/are used economically.

Claims (18)

1. A heat-storage stove comprising a thermally insulated shell containing one or more heating compartments in thermal contact with a system of ducts communicating with a chamber which serves as a heat source, wherein such chamber is equipped with an electric heating assembly comprising one or more resistance heating elements carried by a refractory armature and arranged so that air can freely circulate between the elements and the armature.

2. A method of converting a heat-storage stove comprising a thermally insulated shell containing one or more heating compartments in thermal contact with a system of ducts communicating with a combustion chamber which serves as heat source, wherein any burner is removed from such combustion chamber and such chamber is then equipped with an electric heating assembly comprising one or more resistance heating elements carried by a refractory armature and arranged so that air can freely circulate between the elements and the armature.

3. A heat-storage stove or method according to Claim 1 or Claim 2, in which the heating element is rated at less than 13 amp.

4. A heat-storage stove or method according to Claim 3, in which the heating element comprises a 2.5 kW heater. 5. 15. A heat-storage stove or method according to any preceding claim, in which an outer insulating casing is provided surrounding the shell.

5. A heat-storage stove or method according to any preceding claim, in which the armature is cruciform in cross section.

6. A heat-storage stove or method according to Claim 5, in which the armature comprises a pair of generally similar plates having slots extending half the length of the plate and with a width substantially equal to the thickness of the plate.

7. A heat-storage stove or method according to any preceding claim, in which the armature is formed of an aluminium silicate material.

8. A heat-storage stove or method according to any preceding claim, in which the armature is provided with holes through which the element(s) lead.

9. A heat-storage stove or method according to any preceding claim, in which the heating assembly includes a stand for the armature which stand comprises a refractory top plate, having holes for the updraught of air between the heating element(s) and the armature, carried on supports allowing the inflow of air to beneath that top plate. 10. The or each heating compartment.

10. A heat-storage stove or method according to Claim 9, in which the top plate is of a ceramic material.

11. A heat-storage stove or method according to Claim 9 or Claim 10, in which the stand has a height of 60mm or more.

12. A heat-storage stove or method according to any preceding claim, in which the heat source chamber is surmounted by a barrel which is in turn topped with a hot plate for cooking, the heat source chamber and barrel being located adjacent top and bottom ovens, wherein the heating assembly projects into the barrel.

13. A heat-storage stove or method according to Claim 12, in which the heating assembly projects into the barrel by between 60 and 160mm. IE Ο 4 Ο 8 Ο 4

14. A heat-storage stove or method according to any preceding claim, in which components of the stove within the shell are made substantially of cast iron.

15. Use.

16. A heat-storage stove or method according to any preceding claim, in which a thermostatic control is arranged to control the temperature in

17. A heat-storage stove or method according to any preceding claim, in which the heat source is arranged to heat the or each heating compartment at all times including when said compartment(s) is/are not in

18. A heat-storage stove or method substantially as hereinbefore described with reference to the accompanying drawings.