EP0959303A2

EP0959303A2 - Fireplace

Info

Publication number: EP0959303A2
Application number: EP99660080A
Authority: EP
Inventors: Antti Lehikoinen; Mika Nykyri
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-05-20
Filing date: 1999-05-18
Publication date: 1999-11-24
Also published as: FI981123A7; FI981123A0

Abstract

Fireplace comprising a core part of massive heat storing material, such as soapstone, provided with a firebox (1) and at least one side duct (2) for passing combustion gases from above the firebox downward and further into an exit flue, and a substantially continuous steel casing (3) surrounding the core part on the front, back and lateral sides. According to the invention, the steel casing forms the load-bearing structure of the fireplace, and the fireplace comprises an envelope (4) of massive heat storing material, such as soaps-tone. In addition, the steel casing (3) forms a vertical air duct (5) whose interior wall (12) forms the outer surface of the side duct (2) while the exterior wall (13) is in contact with the envelope (4). The inlet opening (6) of the air duct (5) is located in the lower part of the fireplace while the outlet opening (7) is located in its upper part.

Description

The present invention relates to a fireplace as defined in the preamble of claim 1.
Prior art in the field of the invention is represented in the first place by various stoves with a sheet metal casing, with a firebox inside the sheet metal casing and heat storing material surrounding the firebox. After the heat storing material has been heated, it slowly delivers heat through the sheet metal casing into the surrounding space to be heated.
However, stoves with a sheet metal casing have certain drawbacks. Since the stoves store a large amount of heat, they are slow in becoming heated and it is therefore only after a relatively long time that they can deliver heat into the surrounding space to be heated. Moreover, the sheet metal casing of a well-heated stove is often burning hot for a long time, thus constituting an obvious safety risk at least for small children and animals. In addition, a stove with a sheet metal casing is often simple and ascetic in appearance and so it does not meet the aesthetic standards of modern consumers.
The object of the present invention is to eliminate the drawbacks mentioned above. A specific object of the present invention is to disclose a new type of fireplace which is relatively light and simple and can be quickly installed and which efficiently stores heat, delivering it slowly an uniformly over a long time, which also quickly heats the surrounding space to be heated, whose surface temperature is always at a safe low level and which also has a pleasing appearance that can be easily shaped to fit the environment and user preferences.
As for the features characteristic of the invention, reference is made to the claims.
The fireplace of the invention comprises a core part of massive heat storing material, such as e.g. soapstone, provided with a firebox and at least one side duct opening from above the firebox in a downward direction for passing combustion gases from above the firebox downward and further into an exit flue. In addition, the fireplace comprises a substantially continuous steel casing surrounding the core on the front, back and lateral sides. According to the invention, the steel casing forms the load-bearing structure of the fireplace, and the fireplace comprises an envelope of massive heat storing material placed outside the steel casing in contact with it. In addition, according to the invention, the steel casing forms a vertical air duct. The air duct comprises an interior wall, which forms the outer surface of a side duct, and an exterior wall, which is in contact with the envelope. Moreover, the inlet opening of the air duct is located in the lower part of the fireplace and the outlet opening is located in the upper part of the fireplace. Thus, the air duct and the side duct form an effective heat exchanger based on a counterflow principle, in which downward flowing hot combustion gases heat a cooler rising air flow on the well-known counterflow principle so that the air flowing out at the upper end is at a higher temperature than the combustion gases flowing out into the flue at the lower end.
The envelope, made of e.g. relatively thin soapstone plates, having a thickness of e.g. about 35 mm, is attached directly to the steel casing so that it is in immediate contact with it, with practically no gap between them. This prevents excessive heating of the steel casing and ensures effective heat transfer from the steel casing to the envelope.
As compared with prior art, the fireplace of the invention provides the advantage of easy, fast and simple installation as the steel casing holds the core part in place; cheap and relatively light structure; effective heating properties; safe surface temperatures; fast initial heating thanks to the air ducts; and a potential for diversified and vivid variations of external appearance as the steel casing forms the load-bearing structure of the fireplace.
In the following, the invention will be described in detail with reference to the attached drawings, wherein
Fig. 1 presents a perspective view of a fireplace according to the invention, and
Fig. 2 presents a horizontal section through the fireplace in Fig. 1, taken at the level of the firebox above the fire door.
The fireplace presented in the figures comprises a core part of the stove, with a firebox 1 surrounded by massive soapstone pieces 8 at the back and sides. The fireplace has a fire door 9 in front of the firebox and an ash box with an ash door 10 below the firebox, as is known in the art. At the upper end of the core part, i.e. above the firebox, the gas flow is distributed in a known manner into side ducts 2 leading downward on both sides of the firebox at the edges of the firebox, the side ducts meeting in a single duct below and behind the firebox to pass the combustion gases into an exit flue.
The core part is surrounded at the front and back and on both sides by a substantially continuous steel casing 3, which forms the load-bearing structure of the fireplace. Thus, the steel casing encloses the entire core part of the fireplace, with only openings provided in the areas opposite the fire door 9 and the ash door 10. The side ducts 2 are thus formed in a space delimited by the massive soapstone pieces 8 at the sides of the firebox 1, soapstone edge pieces 11 placed at their ends and the steel casing. Thus, hot combustion gases flowing downward in the side duct rapidly and effectively heat the steel casing in this area.
In the area of the side ducts 2, the steel casing 3 has a two-layer structure, in other words, it forms vertical air ducts 5, in which the interior wall 12 of the air duct faces against the side duct 2 and the exterior wall 13 of the air duct delimits the air duct 5 on its outer side.
Mounted in the immediate vicinity of the steel casing 3, i.e. in contact with its exterior surface, on the front side of the fireplace and in contact with the exterior wall 13 on both sides is a soapstone envelope 4. The envelope 4 is in close contact with the steel casing 3 over its entire area.
The air ducts 5 run substantially through the entire height of the fireplace inside the envelope 4, between the interior wall 12 and exterior wall 13 of the steel casing 3, from an intake opening 6 at the lower edge of the fireplace to an outlet opening 7 at the upper edge of the fireplace. The intake 6 and outlet 7 openings are orifices made in the side surfaces of the envelope of the fireplace, and they can be additionally provided with various adjusting or closing elements.
When the fireplace is being heated, its massive core part stores heat rapidly and effectively. However, some of the heat is transferred to the steel casing 3, from which the heat is effectively conducted to the soapstone envelope mounted in immediate contact with it. The envelope also effectively stores heat and delivers it uniformly into the space to be heated. In spite of its good heat storing capability, the fireplace also rapidly heats the ambient air because immediately after a fire has been lit, the combustion gases flowing downward in the side ducts heat the interior wall 12 of the steel casing, which forms the outer surface of the side duct, the air duct 2 being on the other side of said wall. Thus, immediately after a fire has been lit in the fireplace, an efficient air flow starts flowing in the air duct in the opposite direction relative to the gas flow in the side duct, thus quickly circulating and heating the air in the space surrounding the fireplace.
In the foregoing, the invention has been described by way of example by the aid of the attached drawings, but different embodiments of the invention are possible within the scope of the inventive idea defined by the claims.

Claims

Fireplace comprising

a core part of massive heat storing material, such as soapstone, provided with a firebox (1) and at least one side duct (2) for passing combustion gases from above the firebox downward and further into an exit flue, and

a substantially continuous steel casing (3) surrounding the core part on the front, back and lateral sides

characterised in that

the steel casing (3) forms the load-bearing structure of the fireplace,

the fireplace comprises an envelope (4) of massive heat storing material, such as soapstone, mounted to be in contact with the steel casing, and

the steel casing (3) forms a vertical air duct (5) comprising an interior wall (12), which forms the outer surface of the side duct (2); an exterior wall (13), which is in contact with the envelope (4); an inlet opening (6) located in the lower part of the fireplace; and an outlet opening (7) located in the upper part of the fireplace.
Fireplace as defined in claim 1, characterised in that the envelope (4) is so mounted that it is in direct contact with the steel casing (3).
Fireplace as defined in claim 1 or 2, characterised in that the envelope (4) surrounds the steel casing (3) on the front side and on both lateral sides of the fireplace.
Fireplace as defined in any one of claims 1 - 3, characterised in that the fireplace comprises two side ducts (2), located on either side of the firebox.