GB2321298A - Heating apparatus - Google Patents

Abstract

A heating apparatus eg a ceramic or masonry stove, comprises a base (11), a lid (14) and an inner core of modules (12) formed from ceramic refractory material which effectively does not expand over the operating temperature range of the apparatus. The modules include a firebox (15) comprising a base (19), a wall (20), and a lid (22) having a central outlet (23) for heated gases; and a heat radiating column (16) comprising a series of trapezoidal elements (17), wedge elements (24), a half-width cap (25) and a roof element (26). An outer casing of stacked collars (13), cast from similar refractory material, surround and structurally retain the modules. The components are formed such that they can be assembled to construct the apparatus safely and conveniently by persons with normal building skills.

Description

Heating Apparatus This Invention relates to heating apparatus and in particular, but not exclusively, to a type of stove which is commonly known as a ceramic or masonry stove.

Ceramic stoves have been built for centuries and generally consist of a refractory fire box surmounted by an internal flue element, which defines an elongate labyrinth path for the gaseous combustion products and heated air which arise from the fire box. This internal flue is defined by a body of refractory material, which is heated up by the hot gases. A chimney or further flue then surmounts the internal flue. Usually dry wood is burnt once a day in the fire box at a very high temperature (900 c to 10000c) because of the thermal insulating properties of the refractory material. Once the combustion is complete the external chimney is closed off to avoid cooling by that route and the refractory body of the fire box and internal flue radiate heat into the room in the manner of a storage heater. Traditionally such stoves are decorated by means of external tiles cemented around the refractory material.

In these days of ecological concern, ceramic stoves are becoming increasingly popular both because they are a highly efficient way of burning wood and because their high combustion temperature means that they produce a very low level of pollution gases. However, their construction, when traditional techniques are used, is extremely labour intensive and requires particular skills which take a significant time to acquire. Particularly in countries, such as the United Kingdom, where there is no tradition of ceramic stove building, this need for skilled craftsman is a significant limiting factor on the introduction of such stoves.

From one aspect the present invention consists in heating apparatus including an inner core of modules formed from material, which effectively does not expand over the operating temperature of the apparatus, the modules including a fire box and a device to be heated, and an outer casing of stacked collars, which surround and structurally retain the modules.

Using such a construction the Applicant is able to provide a ceramic-style heating apparatus, for which all the elements can be pre-formed, and which can be assembled conveniently and safely by any one having normal building skills.

The device may be a heat radiating column including an internal flue, as described above, or it may be an oven or barbecue.

A variety of refractory materials may satisfy the requirement for the extremely low coefficient of expansion over the operating temperature range of the apparatus, but it is greatly preferred that the selected material should be capable of being cast. Thus cordierite has suitable thermal characteristics and can conveniently be used as a mixture or fondue of a refractory grade cement and a cordierite aggregate. In that case it is preferred that the aggregate is at least 50% by weight of the mixture.

The small expansion of the inner core, means that only a very small gap needs to exist between the inner core and the collars and typically this would be in the range of 1.5mm-5mm with a gap of about 2mm being particularly preferred. A larger gap would be required adjacent the fire box where the range is likely to be around 20mm-25mm with a gap of 22mm being particularly preferred.

The apparatus may further include a base for supporting both the modules and the collars and a top where appropriate.

The low coefficient of thermal expansion of the inner core means that the thermally induced stresses and strains on the collars is relatively low. This means the apparatus can utilise a whole range of decorative techniques, which were not previously available. Alternatively, if the collars carry traditional tiles, they will not become separated from the stove in the way that usually occurs with traditional ceramic stoves.

From another aspect the invention consist in method of constructing heating apparatus, comprising forming an outer casing of stacked collars and, as the casing is built up, placing inner core modules within the collars so that modules subsequently structurally retained by the collars, the modules being formed from material which effectively does not expand over the operating temperature range of the apparatus, the modules including at least a fire box and a device to be heated.

The method further includes providing the features of the apparatus previously defined.

Although the invention has been defined above, it is to be understood it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and a specific embodiment will now be described with reference to the accompanying drawing, which is an exploded view of a heating apparatus or stove.

A stove is generally indicated at 10. The stove 10 comprises a base 11, an inner core generally indicated at 12, a stack of outer collars 13 and a top or lid 14.

The lower part of the stove 10 forms a fire box 15, whilst the upper part 16 constitutes a heat radiating column, which defines an extended internal flue.

Taking the fire box 15 first, the lower most collar 13a encloses two standard trapezoidal sections 17 so that they define a plenum 18 into which air can be drawn by means of an opening in the column 13a. A fire box base 19, sits on top of the elements 17 and is facetted to concentrate the heat. This base is in term surmounted by the fire box wall 20 and both it and it's associated collar 13b have an opening 21 for the fire box door (not shown). A lid 22 sits on top of the wall 20 and has a central outlet 23 through which heated gases can pass.

The heat radiating column 16 essentially comprises a series of standard trapezoidal elements 17 which are in turn separated by further wedge elements 24. This column is effectively capped by a half width element 25 and a church roof element 26. As can be seen in the drawings certain cutaways are provided in appropriate trapezoidal elements 17 which allow the gases to pass initially up the central canal, between the trapezoidal section 17 until they reach the underside of the church roof 26 and the canal cap 25.

They are then drawn down the channels towards the front of the stove shown in the drawing by the action of the chimney, until they reach the bottom chamber immediately above the fire box lid 23. Here they turn through 180 again and are drawn up the rear canals, defined in the elements 17 to pass over the top of the church roof and exit the stove to a flue connected to the outlet 27, which may be offset in the lid 14. The gases by this time have been cooled from the combustion temperature of around 1000C to a temperature between approximately 160 and 2000c. The flow of gases may be boosted by air introduced by an intake (not shown) at the rear of the stove and a metal damper may be provided to close off the outlet 27 once the combustion in the fire box has been complete. The damper is positioned above the canal cap 25 and church roof 26 but below the lid 14.

As has been explained above the elements of the inner core 12 are made of a material which hardly expands at all over the operating range of the stove and so only a very small gap is required between the inner core elements and the collars 13. Further the upper section 16 may be rotated to allow for different flue positions when the outlet 27 is offset.

It will readily be appreciated that stoves can be supplied in kit form and are made from a small number of standard elements. The stoves can be simply assembled by progressively stacking up the elements from the base 11 upwards, as shown in the drawings, and forming the stack of collars as the apparatus is assembled, so that each of the elements is correctly retained. The inner core elements are cemented together where necessary and the collars 13 are cemented to each other and to the base and lid as required.

The collars may carry tiles or moulded decorative features or they may be coated with appropriate paint or coatings.

A suitable material for the inner elements is a fondue of refractory grade cement and cordierite aggregate and the elements may be cast on a vibrating table. This produces elements with a very high thermal mass and an extremely low coefficient of expansion.

Claims (6)

1. A heating apparatus constructed entirely of cast refractory material except for a metal damper(s), door and door fittings, the refractory sections being cast from material with a low coefficient of expansion and in such a manner that the apparatus can be assembled conveniently and safely by persons with normal building skills, the apparatus comprising an inner core of modules arranged in order to form a firebox, flueways and/or oven contained in and by an outer casing of stacked collars cast from material similar to that from which the inner modules are cast.

2. An oven as claimed in Claim 1 where some module shapes will have been changed to suit the purpose.

3. A barbecue as daimed in Claim 1 where some module shapes will have been changed to suit the purpose.

4. A tandoor as claimed in Claim 1 where some module shapes will have been changed to suit the purpose.

5. A kleftiko as claimed in Claim 1 where some module shapes will have been changed to suit the purpose.

6. Any combination of heating and cooking facility as claimed in Claim 1 where some module shapes will have been changed to suit the purpose.