GB2049163A - Solid-fuel heating appliances - Google Patents

Abstract

A solid-fuel heating appliance consists of three box-like frames (1, 2, 3) stacked one on another. The middle frame (2) contains a combustion chamber (6) which may have doors (8,9) and a cooking grid (40). The top frame (1) contains a water container (24) traversed by ducts (25) for extracting heat from combustion products flowing to the outlet (5). The water container is connected to a hot water or central heating system. The combustion chamber (6) may contain a fire grate (20) composed of water tubes connected to the water container (24) and the external system. The bottom frame (3) contains an ash- collecting drawer (11) with air inlet holes (11.2) and an air control slide, and a wood store (12) below. <IMAGE>

Description

SPECIFICATION Heating appliance This invention relates to heating appliances, in particular solid-fuel fireplaces provided with heat exchangers which can be connected directly or indirectly to a central heating system or to a central hot water system.

Open fireplaces have a low thermal efficiency and are therefore not installed without other heating facilities. It may therefore be assumed that in most cases a central heating system is provided in addition to the open fireplace.

A large number of free-standing fireplaces, fireplace inserts, tiled stove inserts and freestanding oven-like structures are known, in which the smoke and gases, which are still warm after they are discharged from an open fire or a fire which burns behind a door, are utilized for heating water so that this portion of the energy of the fuel is not allowed to escape into the chimney without being utilized.

The invention relates to fireplaces, ovens or like enclosed fireplaces, more particularly for use with solid fuels, which are known under the term "fireplace" as disclosed in the claim, without being confined to conventional open fireplaces. Such fireplaces with a combustion chamber and a heat exchanger for connection to a central heating system and/or central water heating system are known. It is the object of the invention to improve the range of use of such fireplaces, more particularly by the adoption of design measures in manufacture and for transportation, and to improve the efficiency of utilizing the heat contained in the combustion products.

According to the invention the appliance has a frame structure which comprises three box-shaped frames, which are constructed so that they can be stacked one above another and of which the topmost frame accommodates the heat exchanger, the middle frame accommodates the combustion chamber and the bottom frame accommodates an ash collecting place; a storage place for solid fuel, e.g. logs, can also be provided in the bottom frame where appropriate. The appliance is constructed in module configuration, i.e. its individual components can be easily assembled and, where appropriate, can be exchanged. Although it is intended mainly for new buildings it can also be installed in existing fireplaces, so-called open fireplaces.

Since it comprises three parts, which are industrially prefabricated and of which the middle part is usually the heaviest, it can also be readily transported through small doors in buildings to any desired place and can be transported in this manner without large handling equipment, this feature representing a particular advantage. The individual components can also be differently constructed and can be optionally assembled for different purposes.

The heat exchanger is connected to the central heating system and/or to a central hot water system for non-mains water and thus utilizes the energy contained in the combustion products of an open fireplace or of a stove provided for space heating, in order to supply the heat to other rooms or to the hot water system. it is connected like a radiator but by contrast thereto thermal energy is fed into the central heating system, not obtained therefrom.

Doors in front of the combustion chamber ensure improved combustion and better utilization and such doors can be glass doors where appropriate so that the fire is visible.

Ash can be readily collected and very easily removed if the bottom box-shaped frame is provided with a drawer functioning as ash collector.

Peripheral strips ensure good centring and sealing between individual components.

Wood can be readily burnt without a great deal of ash on a floor of the combustion chamber comprising a refractory tile with apertures. Ash is swept through the apertures into the ash box. The apertures also serve to control the air supply. To this end the front wall of the ash box can be provided with air flow apertures, the cross-section of which can be altered by means of an actuating element.

The combustion chamber may have a fire grate comprising pipes assembled in known manner as a cooling coil, which can be connected to the water circuit. Conveniently, one end can be connected to the heat exchanger, and the other end of the pipes and a feed pipe of the heat exchanger can be connected to the central heating system or the like.

The middle box-shaped frame can be provided with a vertically adjustable pivoting arm the free end of which is constructed to receive a grilling grid so that the most diverse foods can be cooked or grilled in the open fire with open or closed doors. Hot drinks or water for coffee or tea can also be constantly kept in readiness on such grids.

Conveniently the heat exchanger comprises a water container with combustion-product flow ducts which are aligned in the fireplace draught direction as is known for different embodiments of other fire systems. This advantageous arrangement is advantageously adapted to the temperature and pressure conditions so that the chimney does not become fouled. Particularly good heat utilization is obtained if the top, box-shaped frame is provided with an upwardly converging internal chamber which merges into an combustionproduct extraction aperture. Combustion and utilization of thermal energy can be improved if an adjustable damper flap, which alters the aperture cross-section, is provided in the ex traction aperture.

To prevent damage due to averheating, the water container can be provided with a pressure relief safety device of the kind suitable, but not necessary, for all kinds of heating apparatus with water heating.

In another advantageous embodiment a thermostatically controlled cooling coil, which is preferably exchangeable, can be disposed in the water container so that the aforementioned pressure relief safety device need not too frequently discharge system water. In the event of overheating, the system water of the central heating system independently conducts cooling water through the aforementiond cooling coil so that the water in the water container can be cooled down to a subcritical value within a few minutes if insufficient heat is drawn off and the fire is too large.

Further details of the invention will be explained by reference to the accompanying drawing, which shows one embodiment of the invention: In the drawing, three box-shaped frames 1, 2, 3 are shown disposed one above another in an expanded view; in practice these three box-shaped frames 1, 2 and 3 are stacked one upon another. The box-shaped frames 1, 2 and 3 have side walls which are joined to form the side walls of the fireplace and consist of refractory materials. The uppermost boxshaped frame 1 is provided with an upwardly converging internal chamber 4 which merges into an extraction aperture 5 for combustion products viz smoke and gas. Depending on local conditions, the said extraction aperture is disposed in the rear wall or in the top covering wall of the box-shaped frame 1.The boxshaped frame 2 has a uniform internal space 6 which forms the combustion chamber into which the fire opening 7 opens. The latter can be closed by doors 8 and 9. The interior chamber 10 of the lowest box-shaped frame 3 is subdivided by an ash box 11 into an ash collecting region, in the ash box, and a log storage space 1 2 beneath the ash box. The ash box 11 is constructed in the manner of a drawer and is open at the top, while a refractory tile, not shown, is provided at the hot tom. At least the box-shaped frames 2 and 3 are provided with a peripheral strip 1 3 or 14, more particularly of copper, so that the boxshaped frames 1, 2 and 3 can be stacked one upon another. Additional peripheral strips 15, 16, also of copper, can be provided for visual reasons but also improve the stability of the frame structure.

A fire grate 20 is provided within the combustion chamber 6 and comprises a pipe coil which extends along a horizontal plane transversely through the fireplace and along a perpendicular plane parallel with the rear wall.

Bars 1 7 and 18 can be provided for support and mounting purposes and each of the bars 17, 1 8 having limbs disposed at right angles to one another. A water supply pipe 21 and a discharge pipe 22 extend to the tubular fire grate 20.

A heat exchanger 24 comprising an enclosed box and a plurality of combustion product flow ducts 25, oriented in the direction of the fireplace draught and extending from the bottom of the water box to its top, are disposed in the bottom region of the internal chamber 4 of the top box-shaped frame 1. A supply pipe 26 extends into the interior of the water box 24 and a discharge pipe 27 is connected to the pipe 22. It is also possible to subdivide the water box so that one half of the interior is connected to the pipes 21 and 26 and the other half is connected to the pipes 22 and 27.

Feed and discharge pipes 26, 27 are connected via a thermostatically controlled valve 28 to central heating pipes 29, 30, so that the central heating water can flow through the heat exchanger 24 and through the fire grate 20 (illustrated position of the valve 28), or the water flow is blocked. In the last-mentioned case a connection can be provided on the one hand between the pipes 26, 27 and on the other hand between the pipes 29, 30.

Instead of controlling the valve 28 by means of a thermal sensor it is also possible for such control to be applied manually by means of a cock.

A vertical guide rod 35, on which a pivoting arm 36 can be adjusted and pivoted, is provided at one side of the fire opening 7.

The pivoting arm 36 can be secured in position by means of a clamping screw 37. The pivoting arm 36 has a boss-shaped end 38 in which a holder 39 of a grilling grid 40 is or can be inserted and with the aid of the pivoting arm can therefore be maintained at a specific height within the combustion chamber 6. It is possible to lift the grilling grid 40 out of the mounting boss 38 and to pivot the pivoting arm 36 against the wall of the fire opening.

The bottom of the combustion chamber may be formed by a refractory tile which is mounted on the box-shaped frame 2 and has apertures for the ash; alternatively the ash drops directly into the ash box 11 which must then be constructed in a suitable manner or must be provided with refractory lining.

Air flow apertures 11.2 are provided in the front wall 11.1 of the ash box 11. The crosssections of these apertures can be varied by means of a slide for the purpose of regulating the combustion air. An actuating element 11.3, which can slide in a slot, is provided to this end. The combustion air passes through the air flow apertures 11.2 and the flow apertures in the refractory tile of the boxshaped frame on which the fire can burn directly, even without a fire grate. An adjustable damper flap can be provided in the extrac tion aperture 5.

Operation of the described fireplace is as follows: the fire, which heats the pipes of the fire grate by direct contact and thus also heats the water within the said pipes, is kindled on the fire grate 20. If no fire grate 20 is provided the fire is kindled directly on the refractory tile. Due to the chimney draught, smoke and gas from the fire flow upwards through the flow ducts 25 and thus give up heat to the water box 24. As soon as a specific water temperature is reached, the valve 28 is set into the illustrated position so that water circulation through the central heating system is obtained. Otherwise unutilised heat of the open fireplace is thus fed into the central heating system.

The fireplace is also suitable for grilling, frying and baking if it operates with a wood fire. Material to be grilled can also be replaced directly on the grilling grid 40 after this has been attached at a suitable height above the flowing charcoal and the grill 40 can also function as a support for a frying or baking vessel.

In the interest of safety the water box 24 can be provided with a pressure relief valve by means of which steam can be bled off into a discharge.

To avoid the pressure relief safety valve coming into operation and to prevent the loss of system water is convenient to provide the water box with a cooling coil which is fed with cooling water by a thermostatic valve which comes into operation in temperature-dependent manner prior to operation of the safety valve.

The fireplace or indoor stove with a hot water heating system has an attractive external apearance, can be easily produced, can be readily transported as individual components and can be installed with operational reliability and utilizes the heat in the heat exchanger particularly effectively. Converging of the outlet chamber above the pipe 25 ensures that the combustion gases are compressed, thus increasing the residence time of the smoke and gases and improving heat utilization.

Claims (11)

1. A heating appliance comprising three box-shaped frames which can be stacked one on another and of which the middle frame accommodates a combustion chamber for solid fuel, the bottom frame accommodates an ash collector, and the top frame accommodates a water-heating heat exchanger adapted to be connected directly or indirectly to a central heating or hot water system.

2. A heating appliance as claimed in claim 1 in which the bottom frame also accommodates a storage space for solid fuel.

3. A heating appliance as claimed in claim 1 or 2 in which the middle frame has an opening for access to the combustion chamber, and doors for closing this opening.

4. An appliance according to any of claims 1 to 3 in which the bottom box-shaped frame is provided with a drawer functioning as ash collector.

5. An appliance according to any of claims 1 to 4, characterised in that circumferential edge strips are provided for stacking the box-shaped frames one above another.

6. An appliance according to any of claims 1 to 5, characterised in that the bottom of the combustion chamber is formed by a refractory tile with apertures.

7. An appliance according to any of claims 1 to 6, characterised in that the front wall of the ash collector is provided with air flow apertures, the cross-sections of which can be varied.

8. An appliance according to any of claims 1 to 7, having in the combustion chamber a fire grate comprising tubes assembled in the manner of a cooling coil and connected to the water circuit.

9. An appliance according to any of claims 1 to 8, characterised in that the middle box-shaped frame is provided with a vertically adjustable pivoting arm, the free end of which is adapted to receive a grilling grid.

10. An appliance according to any of claims 1 to 9, characterised in that the heat exchanger comprises a water container with ducts for combustion products which ducts are oriented in the combustion draught direction.

11. An appliance according to any of claims 1 to 10, characterised in that the water container is provided with a pressure relief safety device.

1 2. An appliance according to any of claims 1 to 11, characterised in that a thermostatically controlled cooling coil, more particularly an interchangeable cooling coil, is disposed in the water container.

1 3. An appliance according to any of claims 1 to 12, characterised in that the top box-shaped frame is provided with an upwardly converging internal chamber which merges into an extraction aperture for combustion products.

1 4. An appliance according to any of claims 1 to 13, characterised in that an adjustable damper flap, which alters the flow crosssection, is provided in the combustion product extraction aperture.

1 5. A fireplace comprising a frame structure for a combustion chamber and a heat exchanger which can be connected directly or indirectly to a central heating system or to a central hot water system, characterised in that the frame structure comprises three boxshaped frames which can be stacked one above another and of which the top frame accommodates the heat exchanger, the middle frame accommodates the combustion chamber and the bottom frame accommodates an ash collecting place.

1 6. A solid-fuel heating appliance substantially as herein described with reference to the accompanying drawing.