Stoves and furnaces – Fireplaces or accessories
Reexamination Certificate
2000-03-03
2001-09-11
Yeung, James C. (Department: 3743)
Stoves and furnaces
Fireplaces or accessories
C126S515000, C126S536000
Reexamination Certificate
active
06286502
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fireplace assembly, and more particularly to masonry fireplaces.
Masonry fireplaces are well known and have been used for years. Such fireplaces are often preferred over metal wood stoves or metal fireplaces for their aesthetic qualities. However, traditional masonry fireplaces have suffered from several drawbacks. Principal among these drawbacks is that masonry fireplaces often provide inefficient and incomplete combustion, resulting in high levels of air pollution, especially in the form of particulates. This drawback has led some municipalities to ban masonry fireplaces. Yet another drawback of traditional masonry fireplaces is that they often fail to provide adequate ventilation, resulting in smoke exiting the fireplace not through the chimney, but instead “spilling” smoke through the front opening of the firebox.
Another problem with the construction of traditional masonry fireplaces has been that, in general, most masons are unfamiliar with efficient and aerodynamically effective fireplace designs. It has been known for some time that particular fireplace designs, such as the Rumford fireplace design, can provide for more efficient combustion. Unfortunately, the Rumford design requires particular geometries, which include a curved lintel and specific firewall geometry from the bottom of the firebox to the smoke chamber. In addition, the geometry of the smoke chamber, damper, and throat are critical to efficient Rumford fireplace operation. However, even for masons who are familiar with efficient fireplace designs, these particular designs are difficult for most masons to create using only mortar and brick because of the complex non-rectangular geometries that are necessary to achieve these designs.
Some attempts have been made to provide masons with forms to guide construction of functional and efficient masonry fireplaces, but these forms have not been well received. Masons have typically resisted the incorporation of metal forms into masonry fireplaces, mainly because they are accustomed to using the tools and materials of masonry construction, and because they are unaware of the limitations of the strength of masonry. More fundamentally, the expansion of metal within a fireplace may cause the surrounding masonry to crack because of the different degrees and rates of heat expansion between masonry and metal.
Another solution to guide construction of fireplaces has been to provide preformed masonry blocks that when assembled form a fireplace. However, such materials are heavy and expensive to ship and transport compared to the great volumes of materials still available locally.
One such attempt to provide a “kit” is supplied by Superior Clay of Ohio and is made almost exclusively out of extruded clay tiles in various shapes. Although this kit does not provide forms for firebox construction, it does have a single-size chimney breast tile laid on its side and strung on a simple steel angle to form an opening. This design has several drawbacks. Extruded clay tiles are appropriate in compression, as in chimney flues, but not in suspension. Over time the tiles may crack and break down. In addition, the mason must make a difficult cut into the surrounding masonry casing to fit the lintel into the right position. The kits also use very heavy clay tiles to form a variety of smoke chambers—some of which are asymmetrical and result in poor performance. The kit also uses a metal damper placed at the throat and the whole system forms a very shallow “traditional” style Rumford fireplace with interior hearths less than 16″ deep. This system requires consumers to develop new and unfamiliar firing techniques such as “teepee” firing. Most operators, however, install gratings and suffer with its lack of performance, such as dirty-burning and smoke-spilling operations.
Accordingly, what is therefore needed is a fireplace assembly that allows construction of an efficient wood burning masonry fireplace, that provides for good fuel combustion with little resulting pollution, that allows masons to construct such fireplaces quickly and easily primarily with material on hand, that provides forms for the construction of difficult and precise geometries, that does not result in cracking of the masonry due to different expansion rates of the constituent materials of the fireplace assembly, that uses light-weight durable materials for the forming of geometries, and that allows operators to use traditional wood-burning methods.
SUMMARY OF THE INVENTION
The present invention overcomes the aforesaid drawbacks of the prior art by providing in a first aspect a fireplace assembly comprising a smoke chamber and a firebox in fluid communication with the smoke chamber. A masonry casing sits adjacent to the firebox, the casing having a pair of spaced apart side walls which together define an opening to the firebox. A lintel supports at least one chimney breast block across the opening, the lintel extending between the pair of side walls and being supported by the side walls.
In a second aspect of the invention, a masonry fireplace assembly comprises a smoke chamber and a firebox in fluid communication with the smoke chamber. A masonry casing sits adjacent to the firebox, the casing having a pair of spaced apart side walls which together define an opening to the firebox. A damper is mounted above the smoke chamber.
In a third aspect of the invention, a fireplace assembly comprises a smoke chamber and a firebox in fluid communication with the smoke chamber. A masonry casing sits adjacent to the firebox, the casing having a pair of spaced apart side walls which together define an opening to the firebox. The firebox is comprised of a plurality of firebrick, a metal firebox frame for guiding installation of the firebrick, and insulation between the firebox frame and the firebrick.
In a fourth aspect of the invention, a method of constructing a fireplace is provided. A metal firebox frame is formed. At least a major portion of the firebox frame is surrounded with insulation. A plurality of firebrick is placed within the firebox frame to form a firebox. The firebox sits adjacent to a masonry casing, the casing having a pair of spaced apart side walls which together with the firebrick and the firebox frame define an opening to the firebox. A smoke chamber is mounted above the firebox in fluid communication with the firebox.
The various aspects of the present invention have one or more of the following advantages. By providing a lintel to extend across the opening to the firebox to support the chimney breast block, the geometry of the breast and throat of the firebox may be easily and precisely defined by the mason. In addition, the lintel and its support brackets may provide additional reinforcement to the masonry structure and define the ultimate maximum width of the opening of the firebox. The support brackets allow for easy and precise assembly without having to modify the side walls of the masonry casing.
Mounting the damper above the smoke chamber results in an improved draft by allowing the heated gases of the fire to rise relatively unimpeded into the chimney, creating a reduced risk of smoke spillage by inducing the flow of room air into the throat at the top of the firebox opening, and consequently resulting in more trouble-free performance.
By providing a metal firebox frame, the shape of the firebox may be precisely defined, thus allowing even a relatively unskilled mason to construct fireplaces that provide extremely efficient combustion with little pollution. The sloped shape of the rear wall, continuously inclined toward the firebox starting at the base of the wall, also provides advantages for clean burning. By deflecting radiant heat from the fuel load back into the grating, primary combustion temperatures are increased and smoky startup conditions are reduced. This radiant effect also directs more radiant energy into the room without raising the height of the opening to the firebox because of the sloped geometry. Both combustion a
Chernoff Vilhauer & McClung & Stenzel
Yeung James C.
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