Air circulating fireplace

Abstract

The invention provides an improved prefabricated air circulating fireplace. A separate air distribution assembly is positioned generally above the fireplace and a removable hearth is positioned above the fireplace circulation air inlet opening. The air distribution assembly and removable hearth conceal the fireplace circulation air inlet and outlet grilles. The air distribution assembly is adapted to convey convection heat generated by the fireplace. During fireplace operation convection heat is conveyed behind the decorative fireplace facing and discharged at or along the ceiling providing additional opportunities for the use and positioning of combustible mantels and materials on the decorative facing of the fireplace.

Description

FIELD OF THE INVENTION

This invention relates to an improved fireplace of the prefabricated air circulating type and the installation thereof.

BACKGROUND OF THE INVENTION

While historically fireplaces have been used to provide heat and a means for cooking, a modem household usually has a separate stove for cooking purposes and a separate home heating system. Nonetheless, fireplaces are a very common and desirable feature to have in a home in this day and age, although its present day utility has changed somewhat. While it is still common for a fireplace to be a feature in a home to provide heat, it is usually in a supplementary capacity; however, it is also important to many homeowners for a fireplace to have aesthetic attributes since the fireplace is also a primary household feature for people to gather around to socialize or relax. This socializing function of the fireplace is utilized regardless if the fireplace is providing either heat or a view of a fire. In fact, the fireplace usually constitutes the focal point of a room and a substantial portion of the overall cost of the fireplace is related to the materials and labor associated with constructing the aesthetic appearance of the fireplace. In addition, the placement of furniture in a room is usually directed toward or adjacent the fireplace, highlighting the household importance and functionality of the fireplace in the cultural framework that dominates North American and European home life today. Furthermore, it is common place for the household's most valued or treasured items to adorn the fireplace, such as: works of art; crafts; keepsakes; and even items of spiritual value such as an urn containing the cremation ashes of a loved one or pet. Accordingly, consumers make purchase decisions heavily influenced by the overall aesthetic appearance of the completed fireplace and its capability to display valued or treasured household items. The ability to cost effectively provide a warm, comforting and aesthetically pleasing environment are important attributes of a modem fireplace which are the subject of this invention.

Within the last fifty years, prefabricated air circulating fireplaces have been, and continue to be, a popular product category of fireplaces manufactured and sold throughout the world, and especially in North America. Prefabricated air circulating fireplaces have used air as means to cool the outer enclosure of the fireplace to facilitate their installation with combustible framing and materials rather than the traditional brick or stone construction. During fireplace operation, air used to cool the fireplace is heated and some fireplace designs use this heated air to heat the room or dwelling; and other fireplace designs vent this heated air up the chimney to the outside; and still other fireplace designs combine these strategies and direct some heat into the dwelling and some heat to the outside. During the evolution of prefabricated air circulating fireplaces, ducts were used to connect the fireplace's air circulation system to the room. Many of these fireplaces utilize one or more ducts to direct room and/or outside air into the bottom portion of the fireplace air circulation passageways and one or more ducts leading from the upper portion of the air circulation passageways to the room where heated air is discharged. The air inlet and outlet ducts are typically covered with grilles visibly mounted on the face of the fireplace, for example U.S. Pat. No. 4,185,612. One of the drawbacks to this design, is the ductwork that forms part of the fireplace air circulation system is assembled on site and depending on the number of bends and the slope of the ducting, the effectiveness of the air circulation system varies dramatically. This can lead to the overheating of the fireplace and requires the prefabricated fireplace to be constructed for these worst case scenarios adding to the cost of manufacture. In addition, there is a considerable amount of cost involved in installing the ductwork and incorporating it into the framing and the decorative fireplace facing. Subsequently, a compact, self contained prefabricated fireplace that incorporates the complete air circulation system with inlet and outlet openings and grilles positioned on the visible face of the fireplace (requiring no ductwork) has emerged as the most popular style of prefabricated air circulating fireplace in the North American marketplace.

These self-contained prefabricated air circulating fireplaces are also a very broad category of fireplace design manufactured in a variety of sizes, shapes and configurations for use with a variety of fuel types and electricity, and available with various vented and unvented models.

A very popular style of this type of prefabricated air circulating fireplace is designed to be built-in and covered with a decorative facing leaving only the front portion of the prefabricated fireplace exposed to the room. This type of fireplace has a firebox or flame effect apparatus that is positioned within an outer enclosure including one or more air passageways whereby room air is drawn into louvered openings in the lower portion of the fireplace unit, subsequently heated and discharged directly into the room in which the fireplace is situated, through another series of louvered opening on the upper portion of the fireplace unit. In a typical construction, the firebox is fitted with a screen or glass panel.

The inlet and outlet louvers and grilles serve several purposes including the prevention of accidental contact with extremely hot surfaces, concealment of mechanical components and to provide access to fans, gas valves and other controls that may form part of the fireplace. These fireplaces are very cost effective to manufacture, transport, install and are well represented in the product offerings of most major fireplace manufacturers throughout North America and capture a substantial market share of new fireplace sales. In addition, there are a vast number of these fireplaces installed in the existing housing stock throughout North America. These types of fireplaces are well represented in the US and Canadian Patent data bases, for example: U.S. Pat. No. 4,519,376; U.S. Pat. No. 4,793,322; U.S. Pat. No. 5,320,086; U.S. Pat. No. 5,218,953; U.S. Pat. No. 6,295,981 and CA 2,295,459.

Despite all the virtues that make the aforementioned fireplaces popular, these fireplaces have fundamental design features that are not desirable. For example, the prominence of the air inlet and/or air outlet louvers (grilles) detract from the overall appearance of the fireplace and impart to it an “appliance like” appearance. These grilles are a departure from the “clean” look of a traditional fireplace, and that clean look is preferable by most consumers, but the grilles are tolerated as a means of satisfying the desire for heat. Prior art fireplaces attempting to minimize the prominence of grilles on the face of the fireplace have had minimal success or have significantly compromised the circulation of heat into the room. For example, U.S. Pat. No. 5,626,127 discloses a fireplace with inlet and outlet openings positioned within the front opening of the fireplace but these small openings are very restrictive to air flow and require a fan to circulate the air. In addition much of the room air drawn into this fireplace and heated is exhausted up the chimney to the outside thereby reducing the fireplace's heating efficiency. Furthermore, to access the compartment below the firebox, the fireplace grate and firebox floor must be removed and this design would not be acceptable for gas fireplaces where this lower compartment houses the gas valve and one can not be expected to remove the gas burner and firebox floor in order to adjust the flame height for example, particularly if the fireplace has been operating for a while.

Another fundamental drawback of these fireplaces is that both the radiant heat output from the firebox and the convection heat output discharged through the air outlet grille, located immediately above the firebox, are effectively combined at the same location which can quickly lead to an overheating of the prime usable area directly in front of the fireplace. This sometimes causes the user to stop operating the fireplace sooner than desired, when it is still desirable to enjoy the ambiance of the fire itself. In addition, dust that has accumulated within the fireplace air passageways since its last use is also discharged directly into this prime area. These problems are compounded if the fireplace is equipped with a fan which directs the heated air out horizontally with more force. It is also not desirable to breath in air that is substantially elevated in temperature.

Another example of a fundamental drawback of these fireplaces is that it exposes facing materials, mantels, decorative elements and other objects normally placed on the face of the fireplace structure to high temperatures sometimes causing deterioration, damage or discoloration. Consequently for fire safety reasons, the testing bodies responsible for approving these products for sale (e.g. Underwriters Laboratories UL, or American Gas Association AGA, approvals division) require combustible mantel shelves to be substantially elevated above the air outlet. This requirement can result in a combustible mantel shelf having to be placed so high above the fireplace opening that it is aesthetically unpleasing, or for practical purposes too high for its intended use. It can also limit the size of an object such as a painting that can be placed on or above the mantel. Frequently, this problem requires the consumer to make unwanted compromises to the size or construction of the mantel shelf.

In addition, wood burning models are subject to the staining of the decorative face of the fireplace by smoke that escapes from the firebox. Wood burning fireplaces that do not have good draft, or are subject to regular downdrafts etc. soil the decorative face of the fireplace immediately above the firebox opening with dark stains that are very difficult and sometimes impossible to remove.

There is a need for a method and/or apparatus for use with this popular type of prefabricated fireplace that provides a more even distribution of the heat produced by these fireplaces. In addition, there is a need to improve the aesthetic appearance of this popular type of prefabricated fireplace by concealing the air circulation inlet and outlet grilles, while maintaining good air circulation. There is also a need to prevent the decorative face of the fireplace from being exposed to high temperatures and from smoke that escapes from the firebox of wood burning models.

The present invention seeks to solve these problems. The invention comprises a method and apparatus to collect heated air discharged from existing models of prefabricated fireplaces and to convey this heated air and discharge it at a location displaced from the actual air outlet of the prefabricated fireplace. In ways that are otherwise not afforded by this type of fireplace, this device has the capability to cost effectively transform and improve the aesthetic appearance of the fireplace and enhance the distribution of the heated air. Also, the invention may be embodied into the design of new prefabricated fireplaces.

BRIEF SUMMARY OF THE INVENTION

The present invention provides improvements to the heat distribution, the use of combustible finishing materials, and the aesthetic appearance of prefabricated air circulating fireplaces, while maintaining the heating efficiency and cost effectiveness to manufacture, transport, and install these prefabricated fireplaces. The present invention can be utilized on many existing models of prefabricated fireplaces as well as being embodied into new prefabricated fireplace designs. More specifically, the present invention provides a separate air distribution assembly adapted to prefabricated air circulating fireplaces that collects heated air that would normally be discharged into the room from an opening immediately above the firebox and instead conveys the heated air upward behind the decorative facing of the fireplace where it is discharged into the room at or near the ceiling. The air distribution assembly is positioned generally above the prefabricated fireplace and forms a main portion of the fireplace facing. The assembly includes a housing with a vertical air passageway that extends through it with an opening corresponding to the outlet opening of the fireplace. The air distribution assembly conveys the heated air discharged from the fireplace outlet air opening behind the decorative fireplace facing through the assembly for discharge at or along the ceiling. The visible portions of the air distribution assembly may be pre-finished to form the decorative face of the fireplace, or unfinished for subsequent on site finishing. In an alternate arrangement, the separate air distribution system conveys the heated air discharged from the fireplace to an adjacent room. One improvement afforded by this invention is that it conceals from most vantage points the large outlet grilles visibly mounted on the face of the subject prefabricated fireplaces which detracts from the aesthetic appearance of the fireplace. Another advantage of this invention is that it redirects the heated air from the prefabricated fireplace that would normally gravitate up the decorative face of the fireplace exposing the facing, materials, mantel shelves, paintings and other decoration that commonly form part of the completed fireplace to high temperatures that could lead to damage, discoloration, or potential fire hazards. The heated air is instead conveyed in a separate air distribution assembly behind the decorative face of the fireplace thereby keeping the face of the fireplace relatively cool, facilitating the safe use of combustible facing materials in applications that it would otherwise not be safe to do so. This provides the user of this invention with new decorative finishing options. Still another advantage of this invention is that it prevents the quick overheating of the area immediately in front of the fireplace, which is usually where most seating is arranged, by separating the radiant heat output into the room by the firebox from the convection heat output, by conveying the convection heat behind the face of the fireplace for discharge at or along the ceiling. The invention can also increase convection airflow through the prefabricated fireplace with proper sizing of the air distribution assembly whereby the vertical column of heated air within the air distribution assembly greats a chimney effect drawing more air through the prefabricated fireplace.

The present invention also provides a novel fireplace hearth that conceals the prefabricated fireplace room air inlet grilles from view, such as from a seated or standing position, while maintaining room air flow into the fireplace, and this improves the aesthetic appearance of the fireplace. It should be understood that fireplace manufacturers recommend the hearth to be installed below the inlet grille of the prefabricated fireplace so as not to block the flow of room air into the fireplace air circulation system as well as to provide access into the air circulation system where gas valves or fan controls are typically located. Typically these prefabricated fireplaces have the inlet grilles positioned immediately below the firebox leaving insufficient space for a conventional hearth to be positioned in this location. However, the novel hearth assembly provides a hearth section that is generally hollow in construction that has a relatively thick cross-section at the front of the hearth that conceals the inlet grille from most vantage points, and a thin cross-section at the rear portion of the hearth preventing the obstruction of air flow into the inlet grille. In addition, the invention provides for the need with some prefabricated fireplaces to gain access into the air circulation air inlet and/or outlet. Both the air distribution assembly and hearth section can be removable allowing access to the circulation air inlets and outlets. Also, an access opening can be provided on the lower portion of the front panel, or on the bottom panel of the air distribution assembly to gain access to the prefabricated fireplaces air circulation outlet.

The present invention has applications for many types of prefabricated air circulating fireplaces in the marketplace and consequently the specific form in which the invention is to be constructed would vary depending on the application. For example, an electric prefabricated air circulating fireplace does not have a firebox; it has a flame effect apparatus that produces images of flames and glowing embers and therefore does not direct significant amounts of radiant heat at the components of the subject invention positioned in front of the fireplace outlet grille and therefore there would be no need for a heat shield or non-combustible air distribution assembly. Another example of a fundamental difference between different types of prefabricated fireplaces that can affect the construction of the invention is that gas and electric fireplaces do not require a hearth that extends in front of the fireplace opening because they do not generate sparks or contain loose pieces of burning fuel that could roll out of the firebox onto the floor and present a fire hazard, as is the case with wood burning fireplaces. The air distribution assembly of the present invention may be used without a hearth providing all the benefits described except for the concealment of the inlet grille and/or opening. However, a hearth is still commonly used for aesthetic purposes with gas and electric fireplaces. Therefore, a smaller less robust hearth can be utilized in gas and electric fireplaces to reduce cost and/or take advantage of other aesthetic design opportunities that could not be utilized with the hearth requirements of wood burning fireplaces.

While the present invention could be embodied in a single construction that addresses the various prefabricated fireplace applications and provide for extreme levels of radiant and convection heat, it is more practical to construct the elements of the invention tailored to a smaller range of fireplace applications so consumers are not burdened with additional costs built into the invention that are not needed in their particular application. For example, in the case of a wood burning air circulating fireplace that can generate a substantial amount of radiant heat as well as the occasional flame tips projecting out of the firebox, the air distribution assembly could be constructed with a housing made of sheet metal that has an outer casing positioned in a spaced relationship in front of the housing. In this construction the housing conveys the convection heat from the outlet air opening upward behind the decorative fireplace facing and protects the outer casing from excessive radiant heat or occasional flames. The air space between the outer casing and the housing keeps the outer casing relatively cool and facilitates the safe use of combustible materials. The outer casing may be attached to the housing with spacers or channels to secure it in a spaced relationship to the housing. Subject to the proximity of the side panels of the housing to the outlet air opening and firebox, only the front panel of the outer casing should need to be spaced from the housing in most cases. Alternatively, in a gas fireplace installation, a single housing of non-combustible or combustible construction in combination with a heat shield on the lower portion of the inner surfaces of the housing could be safely utilized in a more cost effective construction of the invention.

In one embodiment of the present invention, the air distribution assembly is adapted for use with an air circulating fireplace having inlet and outlet air openings on the face of the fireplace. The air distribution assembly may be constructed with common materials such as wood and metal or materials that can be molded into complex shapes such as with glass reinforced gypsum or glass reinforced cement. The air distribution assembly includes a housing constructed of one or more panels joined together, with the housing disposed generally above the fireplace. The housing extends at least the width of the outlet air opening and includes a front panel that projects in front of the outlet opening. The housing also includes side panels and a rear panel with the rear panel disposed in a spaced relationship from the front panel so that the inner surfaces of the front, side and rear panels of the housing define a substantially vertical air passageway extending through the housing. The bottom edge of the rear panel is disposed in close proximity to the top of the outlet air opening. While it is possible in some applications for the room wall along which the fireplace is installed to be used as a rear panel of the housing, the use of a separate rear panel is recommended. The bottom edge of the rear panel is positioned above the bottom edges of the front and side panels by a dimension that corresponds to the height of the fireplace outlet air opening, providing an opening in the lower portion of the housing adapted for flow communication between the fireplace outlet air opening and the air passageway. An opening is provided in the upper portion of the housing that is in flow communication between the room and the air passageway. During fireplace operation, air flows from the room in which the fireplace is situated, in through the fireplace inlet air opening and through the fireplace, and out through the outlet air opening into the air distribution assembly, and out through the air distribution assembly into the room in which the fireplace is situated. The front and side panels that form the housing may be constructed of decorative materials to form a portion of the decorative facing of the completed fireplace structure. Additional embodiments of the present invention include: a removable hearth that is adaptable to dispose above the inlet opening, whereby air flows beneath the hearth into the air inlet air opening; an opening provide in the lower portion of the housing that is in flow communication between the room in which the fireplace is situated and the air passageway permitting room air to flow into and through the air passageway; a heat shield disposed in a spaced relationship to one or more inner surfaces of the housing to intercept the radiant heat generated by the metal and/or glass surfaces of the prefabricated fireplace to prevent portions of the housing from getting too hot; one or more support members secured to inner surfaces of the housing providing structural rigidity to the housing and a means to facilitate the attachment of mantel shelves and wall decor items with the support members constructed and arranged so as not to adversely affect the air flow through the air passageway, (e.g. vertically arranged metal channels, angles etc.); an outer casing constructed of one or more panels positioned in front of the housing so that at least the front wall of the outer casing is disposed in a spaced relationship in front of the housing so that materials used to construct the outer casing will be shielded from the heat of the fireplace permitting the use of combustible materials or temperature sensitive materials to be used to form the decorative facing for the fireplace; at least one opening located in proximity to a lower edge and an upper edge of the front wall of the outer casing to permit the flow of circulation air between the housing and the front wall to provide a cooling effect to the front wall;a top plate disposed on the top of the housing with the top plate having at least one flanged opening in flow communication with the air passageway and adapted for the connection of at least one duct, to convey heated air from the housing to a room other than where the fireplace is situated; apertures or openings located on the top surface of the hearth permitting air to flow through the hearth into the air inlet opening; a pivot means adapted to the hearth whereby the hearth can be pivoted upward to facilitate access to the inlet air opening; an electrical disconnect switch adapted to the hearth for gas fireplace applications whereby the displacement of the removable hearth causes the fireplace to be shut off.

The foregoing and still further objects and important advantages of the present invention will become more fully apparent from the ensuing description and the accompanying drawings, although referring to a specific construction of my invention, is by no means intended to restrict the same to the actual disclosure.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a front view of a prior art prefabricated air circulating fireplace.

FIG. 2 is a front view of an embodiment of the present invention used in conjunction with the fireplace of FIG. 1.

FIG. 3 is an enlarged cross-sectional side view, taken along line 3-3 of FIG. 2.

FIG. 4A-4C illustrate cross-sectional side views of variations in construction of the air distribution assembly according to the invention and the top portion of the fireplace of FIG. 3.

FIG. 5A-5D illustrate perspective front views of the hearth of the present invention and the fireplace of FIG. 3.

FIG. 6A and FIG. 6B are enlarged cross-sectional side views of the hearth and pivoting means, taken along line 6A-6A of FIG. 5A and line 6B-6B of FIG. 5C, respectively.

FIG. 7 is a partially fragmented perspective front view of an embodiment of the air distribution assembly and a removable, cantilevered hearth with apertures.

FIG. 8 is a perspective front view of an embodiment of the present invention used in a new installation of a prefabricated fireplace.

FIG. 9 is a perspective front view of an embodiment of the present invention in a new prefabricated fireplace design.

FIG. 10 is an enlarged cross-sectional side view of the fireplace of FIG. 9, taken along line 10-10, with the air distribution assembly attached to the fireplace.

Corresponding reference characters indicate corresponding parts throughout several views of the following description and drawings.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a front view of a prior art air circulating fireplace installed in a typical application with a raised hearth and a mantel shelf is illustrated. Prior art fireplace 10 has inlet grille 11 and outlet grille 12 visibly mounted on the face of the fireplace positioned below and above firebox 13, respectively. During fireplace operation, radiant heat is directed into the room from firebox 13 and convection heat is directed into the room from outlet grille 12, located immediately above firebox 13. Heated air discharged from outlet grille 12 flows upward in front of the decorative fireplace facing exposing facing materials, mantel, paintings or other ornamentation to high temperatures.

Referring to FIG. 2, an embodiment of the present invention used in conjunction with the same prefabricated fireplace shown in FIG. 1 is illustrated. Air distribution assembly generally designated 20, is positioned above prefabricated fireplace 10 with the lower portion of air distribution assembly 20 projecting below the top of prefabricated fireplace 10 concealing outlet grille 12 from eyesight, such as viewed from a standing or seated position. A hearth 30 is positioned in front of prefabricated fireplace 10 with the horizontal surface of hearth 30 positioned above inlet grille 11, concealing inlet grille 11 from eyesight as viewed from a standing or seated position. During fireplace operation, radiant heat is directed into the room from firebox 13 and convection heat from outlet grille 12 is directed behind the decorative face of the fireplace through air distribution assembly 20 and discharged at or along the ceiling, thereby separating the radiant heat output into the room from the convection heat output into the room. Heated air discharged from outlet grille 12 flows upward behind the decorative face of the fireplace keeping mantels, facing materials, paintings or other ornamentation relatively cool, unaffected by the convection heat discharged from outlet grille 12. The comparison of FIG. 2 with FIG. 1 illustrates the effectiveness of the invention in concealing inlet grille 11 and outlet grille 12 of a typical prior art prefabricated fireplace.

Referring to FIG. 3, an enlarged cross-sectional side view, taken along line 3-3 of FIG. 2 is shown. Prefabricated fireplace 10 includes a firebox 13 with a fire viewing opening 18, and a fireplace enclosure 16 having a front opening 19 disposed around firebox 13 in a spaced relationship forming one or more circulation air passageways 17, for room air to be heated. Inlet grille 11 is positioned in inlet air opening 14 located below firebox 13, with inlet air opening 14 in flow communication between the room and circulation air passageway 17. Outlet grille 12 is positioned in outlet air opening 15 located above firebox 13, with outlet air opening 15 in flow communication between circulation air passageway 17 and housing 21 of air distribution assembly 20.

Air distribution assembly 20 is a separate assembly adaptable to dispose generally above prefabricated fireplace 10. Air distribution assembly 20 includes a housing 21 with an air passageway 24 that is functional to redirect heated air discharged from prefabricated fireplace 10 behind the finished decorative facing of the fireplace, and discharging it into the room at or along the ceiling. Air distribution assembly 20 further having an outer casing 35 constructed of one or more panels disposed in front of housing 21 to form part of the decorative facing of the completed fireplace. In applications where prefabricated fireplace 10 generates a substantial amount of heat, one or more panels of outer casing 35 may be mounted in a spaced relationship to housing 21 forming air space 37 with the use of spacers or channels 76, as illustrated in FIG. 9. In this embodiment, outer casing 35 has a front wall 36 positioned in a spaced relationship in front of housing 21. Housing 21 having a front panel 22, side panels 23, rear panel 25 and bottom panel 29 defining a substantially vertical air passageway 24 extending through housing 21. Front panel 22 is positioned in front of outlet grille 12 of prefabricated fireplace 10 with the lower portion of front panel 22 extending below the top of prefabricated fireplace 10. Preferably, outlet grille 12 is removed to allow the heated air to flow directly through outlet air opening 15 into air passageway 24. Rear panel 25 has an opening 26 in the lower portion of housing 21 adapted for flow communication between air passageway 24 and outlet air opening 15. The lower portion of front panel 22 is spaced in front of outlet air opening 15 to provide sufficient air space to optimize the convection air flow through prefabricated fireplace 10. The spacing of front panel 22 in front of outlet air opening 15 can be approximately by calculating the effective opening area of the outlet grille 12, and positioning front panel 22 so that there is an equivalent cross-sectional opening area in air passageway 24, in the area immediately in front of the outlet opening 15. If air distribution assembly 20 is to be constructed for a specific line of prefabricated fireplaces, the optimum size of the air passageway 24 could be determined very simply through actual testing. An opening 27 is provided in the upper portion of housing 21 that is in flow communication between air passageway 24 and the room in which the fireplace is situated. Opening 27 is located on the top of housing 21 and extends the width and depth of housing 21. Bottom panel 29 is removably mounted to the bottom of air distribution assembly 20 to provide access into air passageway 24 and outlet air opening 15, if required. Front panel 22, side panels 23, rear panel 25, and bottom panel 29 are constructed of sheet metal and have internally disposed structural members 52, as illustrated in FIG. 7, to provide structural integrity to air distribution assembly 20.

One or more openings 38 and 39 are located in proximity to a lower edge and an upper edge, respectively, of front wall 36 of outer casing to permit the flow of room air between front wall 36 and housing 21, shown as air flow 40. Air flow 40 minimizes the transmission of heat from housing 21 to front wall 36. The outer surfaces of outer casing 35 may be pre-finished for example with wood veneer, decorative metal, paint or other decorative coatings etc. Alternatively, the outer surfaces of the outer casing 35 may be provided as unfinished surfaces to be subsequently covered or coated on site with materials to form the decorative fireplace facing.

Hearth 30 is constructed to conceal the inlet grille 11 from a typical vantage point such as from a seated or standing position while facilitating the flow of room air into inlet air opening 14. In situations where access is required to the inlet air opening 14 for servicing or to access concealed controls located behind inlet grille 11, hearth 30 is constructed to be removable. Hearth 30 has a top section 32 and a front section 33. Top section 32 extends outwardly from the front of prefabricated fireplace 10 into the room. Front section 33 extends downward from the front edge of top section 32 providing rigidity to hearth 30 and a means to conceal inlet grille 11 from eyesight. Hearth 30 is generally hollow in construction or has one or more cavities beneath top section 32 that extend to the rear edge of top section 32 so that room air is permitted to flow into inlet air opening 14 even though it appears to be blocked off by the apparent thickness of hearth 30, established by the downward projection of front section 33. Hearth supports 31 are attached to front section 33 and top section 32 providing structural reinforcement to hearth 30. To ensure the adequate flow of room air into inlet air opening 11, the bottom edge of front section 33 is spaced above any floor or secondary hearth surface to provide an opening of equivalent size or greater than the effective opening area of inlet grille 11. Hearth 30 may comprise the entire hearth assembly or it may be constructed as one of several segments that form the overall hearth assembly, as a means of minimizing the size and weight of hearth 30 that needs to be removed, as illustrated in FIG. 5A-5D. With further reference to FIG. 5A-5D, hearth 30 is supported on recessed flanges 47 of hearth segments 46.

During fireplace operation, room air flows underneath hearth 30 and through concealed inlet grille 11 into inlet air opening 14 where the room air is heated in circulation air passageway 17 of prefabricated fireplace 10 and discharged from outlet air opening 15 through outlet grille 12. The heated air discharged from the outlet air opening 15 is prevented by the air distribution assembly 20 from entering directly into the room. The increased buoyancy of the heated air (compared to room air) causes it to flow upward in air passageway 24 and through top opening 27 whereby it is discharged into the room. Air passageway 24 contains the heated air as a vertical column of air, and if properly sized, air passageway 24 creates a chimney effect that increases the convection air flow through prefabricated fireplace 10. Alternatively, a fan can be utilized to circulate air through fireplace 10 and air distribution assembly 20.

In alternate arrangements, variations in the construction of air distribution assembly 20 are illustrated in FIG. 4A-4C. With specific reference to FIG. 4A, air distribution assembly 20 illustrates air passageway 24 positioned between front panel 22 and rear panel 25. An opening 26 is located in the lower portion of housing 21 and is in flow communication between air passageway 24 and outlet grille 12. Bottom panel 29 may be removably mounted to provide access to outlet air opening 15, if required. Front panel 22 and side panels 23 form part of the decorative face of the fireplace. The outer surfaces of front panel 22 and side panels 23 may be pre-finished, or unfinished for the subsequent covering with a material or coating that forms the decorative face of the fireplace. During fireplace operation, heated air 34 is discharged from fireplace outlet grille 12 into air passageway 24 whereby it is conveyed upward behind the decorative fireplace facing and discharged into the room air, though opening 27 located in the upper portion of the housing.

With reference to FIG. 4B, front panel 22 and side panels 23 have a complex shape made with the use of molds including molded-in decorative features such as a mantel shelf and cornice and made for example of glass reinforced gypsum or glass reinforced cement. An opening 28 extends across the bottom of housing 21 to permit the flow of room air into housing 21. Heat shield 41 is positioned in a spaced relationship to the inside surface of front panel 22 to intercept the radiant heat directed at front panel 22 from the metal and/or glass front of prefabricated fireplace 10. The space between heat shield 41 and the inner surface of front panel 22 permits room air to flow therethrough, shown as air flow 42, cooling the inner surface of front panel 22. Subject to the nature of a particular prefabricated fireplace and its surface temperatures during operation, and also subject to the engineering properties of the material used to construct front panel 22, heat shield 41 may not be required. For example, if prefabricated fireplace 10 is an electric fireplace and contains a flame simulating apparatus instead of a firebox, it is most likely that heat shield 41 would not be required. During fireplace operation, heated air flows through fireplace 10 into and through air passageway 24 and out top opening 27 into the room, shown as air flow 34. Air flow 34 creates an updraft that draws room air through bottom opening 28 into air passageway 24, shown as air flow 43. Air between front panel 22 and heat shield 41 rises upward into air passageway 24, shown as air flow 42. Air flows 42 and 43 into air passageway 24 reduce the surface temperature of front panel 22 and join with air flow 34 and are discharged through top opening 27 into the room at or along the ceiling.

With reference to FIG. 4C, the upper portion of rear panel 25 is formed rearward increasing the distance between front panel 22 and rear panel 25. Top plate 44 is disposed on the top of housing 21. Top plate 44 has one or more flanged openings 45 in flow communication with air passageway 24 and are adapted for the connection of ducts (not shown) for the purpose of conveying heated air flow 34 from housing 21 to a room other than where the fireplace is situated. Outer casing 35 is constructed of one or more panels and is disposed in front of housing 21 with an air space 37 between front wall 36 and front panel 22. One or more openings 38 and 39 are located in proximity to a lower edge and an upper edge, respectively, of front wall 36 to permit the flow of room air between front wall 36 and front panel 22. During fireplace operation, heated air 34 is discharged through outlet grille 12 into air passageway 24 where it is conveyed upward through housing 21, and discharged through flanged opening 45 into one or more ducts (not shown) whereby it is conveyed to an adjacent or upper room. Air between front panel 22 and front wall 36 increases in temperature through the transmission of heat from front panel 22 and room air flows therebetween, shown as air flow 40.

Numerous variations to these embodiments could be made that would fall within the scope of the invention. For example, bottom panel 29 may contain openings to introduce room air that could be drawn into air passageway 24. Also, bottom panel 29 and heat shield 41 could be constructed as one multifunctional piece. In addition, opening 27 in the upper portion of air passageway 24 in flow communication with the room could be formed laterally through front panel 22, or through one or more side panels.

With reference to FIG. 5A-5D, four views of removable hearth 30 illustrate the concealment of inlet grille 11 and the accessibility to inlet grille 11 by pivoting or removing hearth 30. In reference to FIG. 5A, hearth 30 is positioned in front of prefabricated fireplace 10 with the horizontal surface of hearth 30 positioned above inlet grille 11. When viewed from most vantage points inlet grille 11 is concealed while room air is allowed to flow freely through inlet grille 11 for circulation within prefabricated fireplace 10. In this embodiment, hearth 30 is one of three segments that form the overall fireplace hearth assembly thereby reducing the size and weight of hearth 30 making it easier to remove or pivot to gain access to inlet grille 11. Hearth segments 46 add a traditional look to the overall hearth assembly.

FIG. 5B illustrates hearth 30 completely removed from its normal position in front of prefabricated fireplace 10 thereby revealing inlet grille 11 and providing complete access to controls located behind inlet grille 11. Recessed flanges 47 projecting from hearth segments 46 support hearth 30.

With reference to FIG. 5C and 5D, hearth 30 is pivoted upwards thereby revealing inlet grille 11. Inlet grille 11 is opened to provide convenient access to controls such as gas valves or fan controls etc. without having to remove hearth 30.

With reference to FIG. 6A and 6B, enlarged cross-sectional side views of hearth 30 are illustrated. The fireplace hearth is typically installed below the bottom edge of the prefabricated fireplace 10 so as not to block inlet grille 11. However, it is an object of the invention to conceal inlet grille 11 while facilitating air flow into prefabricated fireplace 10. Since it is most common with prefabricated fireplaces to have inlet grille 11 positioned immediately below firebox 13, there is very little space to accommodate a hearth above the inlet grille. However, the novel hearth assembly provides a hearth 30 that is generally hollow in construction, or has one or more cavities extending to the rear edge of hearth 30 to allow room air to flow into inlet grille 11. Hearth supports 31 are secured to top section 32 and front section 33 to strengthen hearth 30 when the thickness of top section 32 must be minimized to prevent blocking of the inlet air opening. Alternatively, hearth 30 may be molded or cast, with areas of the hearth increased in thickness to form ribs that provide the necessary strength without the use of hearth supports 31. A pivot means 48 is adapted to hearth 30 to facilitate the upward pivoting of hearth 30 thereby providing improved access to inlet opening 14. Pivot means 48 is constructed with formed metal pins 49 that fit into pivot slots 50 that are positioned at the rearward portion of recessed flanges 47. Hearth 30 may be lifted and removed completely or rotate upward. When hearth 30 is pivoted upward, metal pin 49 travels forward in slot 50 where it makes contact with the front portion of slot 50 where further rotation is stopped. The length of slot 50 facilitates a range of movement, or rotation of less than 90 degrees, for safety reasons, to prevent hearth 30 from making contact with prefabricated fireplace 10 which could be very hot. The limited rotation of hearth 30 also prevents it from being left in an inclined position on its own where it could be exposed to excessive radiant heat and consequently a potential safety hazard. An additional embodiment of hearth 30 for use with gas fireplace applications is illustrated in FIG. 6B providing a secondary electrical disconnect switch 51 adapted to hearth 30 whereby the displacement of hearth 30 from its normal position opens the primary circuit used to activate the gas fireplace thereby shutting off the gas fireplace and preventing potential problems with too much heat being directed at hearth 30. Electrical disconnect switch 51 has a spring loaded lever or pin that is depressed by the weight of hearth 30 closing the circuit when hearth 30 is in its normal position thereby allowing a gas fireplace to be tuned on by its primary on/off switch.

With reference to FIG. 7, a partially fragmented perspective front view of an embodiment of air distribution assembly 20 and removable hearth 30 is illustrated. Support members 52 are secured to inner surfaces of housing 21 providing structural rigidity to housing 21. Hearth 30 is cantilevered above inlet grille 11 with support bracket means 53. In addition, apertures 54 are located on top section 32 permitting air to flow through hearth 30 into inlet grille 11. This embodiment has applications when front section 33 extends close to the floor level and consequently does not provide sufficient air flow for circulation through prefabricated fireplace 10. However, providing openings in a hearth undermines the original purpose of a hearth which is to prevent a fire hazard from sparks and/or pieces of burning fuel that may escape out of the firebox, therefore, the use of novel hearth 30 with apertures 54 in applications with wood burning fireplaces necessitates the use of a secondary non-combustible hearth below apertures 54 to preserve the original function of a hearth.

With reference to FIG. 8, the present invention is illustrated when installing a new prefabricated fireplace 10 into an existing home. In this illustration, the entire body of the prefabricated fireplace 10 (shown in broken lines) projects into the room so that the back surface of prefabricated fireplace 10 is in front of the inside surface of a room wall 55. Air distribution assembly 20 is constructed with curved side panels purely for aesthetic reasons. Air distribution assembly 20 forms a major portion of the decorative fireplace facing and is removably mounted with screws and key hole slots (not shown) to fireplace panels 56 that extend from room wall 55 to the air distribution assembly 20 to enclose the projection of prefabricated fireplace 10 into the room. Hearth 30 is positioned in front of prefabricated fireplace 10 and forms one segment of the overall hearth assembly. Hearth segments 46 are curved in construction for aesthetic reasons and extend from room wall 55 and project in front of prefabricated fireplace 10 and are adapted to fit with hearth 30 to provide a continuation of hearth 30 that extends beyond both sides of the decorative fireplace facing.

With reference to FIG. 9 and FIG. 10, FIG. 9 is a perspective front view of an embodiment of the invention incorporated into a new prefabricated fireplace design. FIG. 10 is an enlarged cross-sectional side view, along line 10-10 of FIG. 9 with the air distribution assembly 57 mounted onto the top of fireplace 58. Air distribution assembly 57 is an integral part of fireplace 58 but is constructed as a separate assembly for on-site attachment to fireplace 58 with screws, or the equivalent. Fireplace 58 includes a firebox 59 having a rear, bottom, side and top panels and a front opening for viewing a fire. Fireplace 58 having an enclosure 60 with rear, bottom, side, and top panels and a front opening with enclosure 60 positioned in a spaced relationship from firebox 59 forming one or more circulation air passageways 61 for the purpose of circulating room air to be heated. An inlet air opening 62 is located on the front face of fireplace 58 below firebox 59 and is in flow communication between the room in which the fireplace is situated and circulation air passageway 61. Inlet grille 63 is positioned in front of inlet air opening 62. Enclosure 60 having a top panel 64 with an outlet air opening 65 that extends substantially the full width of the forward portion of top panel 64 and has upwardly formed flanges 66 along its perimeter edges designed to provide structural reinforcement to top panel 64 and an interconnection means between fireplace 58 and air distribution assembly 57.

Air distribution assembly 57 is constructed of sheet metal and comprises an inner housing 67 and an outer housing 68. Inner housing 67 having an air passageway 69 with an opening 70 in the bottom portion of inner housing 67 in flow communication with outlet air opening 65. An opening 71 is provided in the top portion of inner housing 67 in flow communication with the room in which the fireplace is situated. Outer housing 68 is positioned in front of inner housing 67 and having an air passageway 72 that extends below top panel 64 of fireplace 58. The bottom portion of outer housing 68 having an opening 73 extending the width of outer housing 68 in flow communication with the room, and the top portion of outer housing 68 having an opening 74 in flow communication with the room. Outer housing 68 having an outer panel 77 providing a mounting surface for a decorative fireplace facing to project below the top of the fireplace 58 whereby room air is allowed to flow behind the decorative fireplace facing through outer housing 68. Air distribution assembly 57 is designed to have a decorative fireplace facing cover outer panel 77. One or more structural members 75 are secured to inner housing 67 to provide structural support to the air distribution assembly 57 and one or more channels 76 are secured to outer housing 68 to maintain the integrity of the air space between outer panel 77 and inner housing 67. Air distribution assembly 57 is secured with screws (or the equivalent) to conventional wood or metal framing, not shown, used to enclose the fireplace 58. The conventional framing is positioned flush with outer panel 77 so that the decorative fireplace facing materials will be supported by both the conventional framing and the air distribution assembly 57. During fireplace operation, air within the circulation air passageway 61 of fireplace 58 becomes heated, creating a convection air flow that draws room air through inlet grille 63 into inlet air opening 62 where it is circulated and heated within fireplace 58 and discharged from outlet air opening 65 into air passageway 69 whereby the heated air is conveyed upward through inner housing 67 and discharged through opening 71 into the room, shown as air flow 78. As inner housing 67 increases in temperature the air in outer housing 68 is heated and a secondary convection air flow draws in room air through opening 73 whereby the air is conveyed upward, through air passageway 72 of outer housing 68, and out through opening 74 into the room, shown as air flow 79, providing a cooling effect to the decorative fireplace facing to be attached to outer panel 77. A grille 80 is mounted to the top of air distribution assembly 57. An adapter means 81 can be attached to the top portion of the air distribution assembly 57 to direct the heated air ninety degrees whereby the heated air can be discharged horizontally into the room through an opening located in the upper portion of the decorative fireplace facing.

Other modifications or improvements may be made without departing from the scope of the invention.

Claims

1. An air distribution assembly for use with an air circulating fireplace having an inlet air opening and an outlet air opening located on the face of the fireplace comprising:

a housing disposable generally above said fireplace, said housing extending at least the width of said outlet air opening, said housing having a front panel projecting in front of said outlet air opening;

at least one air passageway extending in a substantially vertical orientation through said housing;

at least one opening in the lower portion of said housing adapted for flow communication between said outlet air opening and said at least one air passageway;

at least one opening in the upper portion of said housing in flow communication between said at least one air passageway and the room in which said fireplace is situated;

whereby during fireplace operation, air flows from the room in which said fireplace is situated in through said inlet air opening and through said fireplace, and out through said outlet air opening into said air distribution assembly, and out through said air distribution assembly into the room in which said fireplace is situated.

2. An air distribution assembly as claimed in claim 1, further comprising a removable hearth, said hearth adaptable to dispose above said inlet air opening, whereby air flows beneath said hearth and into said inlet air opening.

3. An air distribution assembly as claimed in claim 1, further comprising at least one opening in the lower portion of said housing in flow communication between said room and said at least one air passageway whereby room air is permitted to flow into and through said at least one air passageway.

4. An air distribution assembly as claimed in claim 3, further comprising at least one heat shield disposed in a spaced relationship to at least one inner surface of said housing.

5. An air distribution assembly as claimed in claim 1, further comprising at least one support member secured to at least one inner surface of said housing providing structural rigidity to said housing.

6. An air distribution assembly as claimed in claim 1, further comprising an outer casing having a front wall disposed in a spaced relationship in front of said housing.

7. An air distribution assembly as claimed in claim 6, further comprising an opening located in proximity to a lower edge of said front wall and an opening located in proximity to an upper edge of said front wall, permitting the flow of circulation air between said front wall and said housing.

8. An air distribution assembly as claimed in claim 1, further comprising a top plate disposed on the top of said housing, said top plate having at least one flanged opening in flow communication with said at least one air passageway, said at least one flanged opening adapted for the connection of at least one duct, whereby heated air from said housing is conveyed to a room other than where said fireplace is situated.

9. An air distribution assembly as claimed in claim 2, further comprising at least one opening located on the top surface of said hearth permitting air to flow from above said hearth, through said at least one opening located on the top surface of said hearth, up to and through said inlet air opening.

10. An air distribution assembly as claimed in claim 2, further comprising a pivot means adapted to said hearth whereby said hearth pivots upward to facilitate access to said inlet air opening.

11. An air distribution assembly as claimed in claim 2, further comprising an electrical disconnect switch adapted to said hearth for gas fireplace applications, whereby the displacement of said hearth causes the gas fireplace to be shut-off.

12. An air circulating fireplace including a separate air distribution assembly for a room to be heated comprising:

a firebox having a front opening for viewing a fire;

an outer enclosure having a front opening, said enclosure disposed in a spaced relationship about said firebox;

a first air passageway between said firebox and said enclosure for circulating air to be heated;

an inlet air opening located below said firebox in flow communication between said room and said first air passageway;

an outlet air opening located above said firebox in flow communication between said first air passageway and a second air passageway provided in said separate air distribution assembly;

a separate air distribution assembly disposed generally above said enclosure with a lower portion of said assembly projecting in front of said outlet air opening, said assembly having a housing defining a substantially vertical second air passageway extending therethrough, said housing having an opening adapted for flow communication between said second air passageway and said outlet air opening and said housing having an opening in flow communication between said second air passageway and said room;

whereby during fireplace operation, room air flows from said room into and through said fireplace, and into and through said air distribution assembly, and back into said room.

13. A fireplace as claimed in claim 12, whereby said fireplace is a gas fireplace.

14. A fireplace as claimed in claim 12, whereby said fireplace is an electric fireplace and said firebox comprises a flame effect apparatus for simulating a fire.

15. A fireplace as claimed in claim 12, further comprising a removable hearth, said hearth adaptable to dispose above said inlet air opening, whereby air flows underneath said hearth, up to and through said inlet air opening, into said fireplace.

16. A fireplace as claimed in claim 12, further comprising an outer casing having a front wall disposed in a spaced relationship in front of said housing.

17. A fireplace as claimed in claim 16, further comprising at least one opening located in proximity to a lower edge and at least one opening located in proximity to an upper edge of said front wall, permitting the flow of circulation air between said front wall and said housing.

18. An air circulating fireplace including a separate air distribution assembly for a room to be heated comprising:

a firebox having a front opening for viewing a fire;

an outer enclosure having a top panel and a front opening, said enclosure disposed in a spaced relationship about said firebox;

a first air passageway between said firebox and said enclosure for circulating air to be heated;

an inlet air opening located below said firebox in flow communication between said room and said first air passageway;

an outlet air opening located on the forward portion of said top panel adapted for flow communication between said first air passageway and a second air passageway provided in said separate air distribution assembly; and

a separate air distribution assembly disposed generally above said enclosure, said assembly having an inner housing and an outer housing, said inner housing having a second air passageway in flow communication with said first air passageway and said room, said outer housing having a third air passageway with a lower opening and an upper opening each in flow communication with said room;

whereby during fireplace operation, air flows from said room into and through said fireplace, into and through said inner housing and back into said room, and air flows from said room into and through the said outer housing and back into said room.

19. A fireplace as claimed in claim 18, further comprising a removable hearth, said hearth adaptable to dispose above said inlet air opening, whereby air flows underneath said hearth, up to and through said inlet air opening, into said fireplace.

20. A fireplace as claimed in claim 18, wherein said outer housing having a front wall that extends below said top panel and is disposed in a spaced relationship in front of said fireplace.