CA2736458C - Unvented gas fireplace - Google Patents
Unvented gas fireplace Download PDFInfo
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- CA2736458C CA2736458C CA2736458A CA2736458A CA2736458C CA 2736458 C CA2736458 C CA 2736458C CA 2736458 A CA2736458 A CA 2736458A CA 2736458 A CA2736458 A CA 2736458A CA 2736458 C CA2736458 C CA 2736458C
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- air
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- combustion chamber
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- room
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- 238000002485 combustion reaction Methods 0.000 claims abstract description 123
- 239000003570 air Substances 0.000 claims description 157
- 239000012080 ambient air Substances 0.000 claims description 28
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 2
- 239000000203 mixture Substances 0.000 abstract description 4
- 239000007789 gas Substances 0.000 description 13
- 206010022000 influenza Diseases 0.000 description 4
- 230000037361 pathway Effects 0.000 description 4
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
- 238000013022 venting Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Direct Air Heating By Heater Or Combustion Gas (AREA)
Abstract
An unvented gas fireplace in which air flow through a closed combustion chamber is controlled by means of a restriction in the air flow path through an outer plenum chamber surrounding the combustion chamber, causing a pressure differential between the plenum and combustion chamber, forcing air from the plenum into the combustion chamber, where it is combusted and mixed with the cool air that has passed the restriction in the plenum, before the air mixture is exhausted into the surrounding room or area. A diverter selects between exhausting the heated air in the same or the opposite side as the air intake. The unit may be used as an outdoor stand-alone fireplace.
Description
TITLE OF INVENTION
UNVENTED GAS FIREPLACE
FIELD OF THE INVENTION
This invention relates to an improved unvented gas fireplace. In particular, the invention relates to an unvented linear gas fireplace in which the air flow into a unvented closed combustion chamber is controlled by a restriction in the path of the air flow through a plenum chamber around the combustion chamber.
BACKGROUND OF THE INVENTION
Gas-fired fireplaces are becoming extremely popular because they are generally cleaner, safer and less expensive to build than wood-fired fireplaces.
Unvented gas-fired fireplaces in particular have become increasingly popular, because they allow the consumer to fit or retrofit a fireplace into any pre-existing room having a gas line, without incurring the costs associated with chimney construction or construction of a venting system. Further, because unvented fireplaces do not require chimneys or flues, it is possible to locate the fireplace in practically any location. For example, the fireplace may be located against a wall, or in a corner, or in the middle of a room, where the flame is visible from two or more sides. The fireplace may also be of any shape and size, depending on the location in which it is to be installed.
Such fireplaces are considered to be highly efficient, drawing room air in for combustion and returning the warmed air directly to the room. However, because unvented fireplaces vent most or all of the combustion products to the directly to the room rather than outside, they must meet rigid standards, requiring that the fireplace burn extremely efficiently in order to minimize the buildup of the combustion products.
U.S. Patent No. 2696205 to Ruhl describes a space heater that operates similarly to a typical unvented fireplace. The heater comprises a heater unit surrounded by a series of flues and baffles. Ambient air passes through the heater section, where it is combusted by a flame within a metal radiant element. The flow of the combustion air from the heater to the surrounding room is partially controlled by a deflecting choke surface, which accelerates expulsion of the heated air by increasing the air pressure at the choke. A second stream of air also freely flows behind the heater unit, through the flues and out the baffles. This second stream of air is warmed by thermal contact with the flues and thus also warms the room, but in addition it serves a cooling function, ensuring that the area immediately around the rear of the heater does not get too hot.
.io U.S. Patent No. 5054468 to Moon et al. describes an unvented fireplace assembly consisting of two chambers, namely a combustion chamber surrounded by a plenum chamber. Ambient air moves through the plenum chamber, warming by contact with the outside of the combustion chamber, before returning to the room in which the fireplace is located. Air is also pulled directly into the combustion chamber by a fan;
the heated combustion air is then expelled back into the room. U.S. Patent No.
5139011 to Moon describes a similar unvented fireplace with a pair of airflow paths.
Ambient air passes through a duct assembly around the combustion chamber, heating the air before returning it to the room. Combustion air is again pulled directly into the combustion chamber by a fan and heated before being returned to the room.
Each of these patents uses a dual intake system, which makes the system more complex, and makes it difficult to maintain a steady flow of air into both airflow pathways. If air moves relatively quickly into the combustion chamber, for example, there may not be sufficient plenum airflow to cool the area outside the combustion chamber. Further, in each of these cases, the combustion air and the plenum air are expelled into the room at different places and likely at different rates. The combustion air is hotter than the radiantly heated plenum air, which can lead to undesirable localized temperature variations.
U.S. Patent No. 5678534 to Fleming and U.S. Patent No. 5906197 to French each disclose a single-intake fireplace in which the incoming airflow is divided into several pathways, one flowing to the combustion chamber, and the others flowing to various convection pathways or plenum chambers surrounding the combustion chamber.
The air from the plenum or convection areas is then mixed with the combustion air
UNVENTED GAS FIREPLACE
FIELD OF THE INVENTION
This invention relates to an improved unvented gas fireplace. In particular, the invention relates to an unvented linear gas fireplace in which the air flow into a unvented closed combustion chamber is controlled by a restriction in the path of the air flow through a plenum chamber around the combustion chamber.
BACKGROUND OF THE INVENTION
Gas-fired fireplaces are becoming extremely popular because they are generally cleaner, safer and less expensive to build than wood-fired fireplaces.
Unvented gas-fired fireplaces in particular have become increasingly popular, because they allow the consumer to fit or retrofit a fireplace into any pre-existing room having a gas line, without incurring the costs associated with chimney construction or construction of a venting system. Further, because unvented fireplaces do not require chimneys or flues, it is possible to locate the fireplace in practically any location. For example, the fireplace may be located against a wall, or in a corner, or in the middle of a room, where the flame is visible from two or more sides. The fireplace may also be of any shape and size, depending on the location in which it is to be installed.
Such fireplaces are considered to be highly efficient, drawing room air in for combustion and returning the warmed air directly to the room. However, because unvented fireplaces vent most or all of the combustion products to the directly to the room rather than outside, they must meet rigid standards, requiring that the fireplace burn extremely efficiently in order to minimize the buildup of the combustion products.
U.S. Patent No. 2696205 to Ruhl describes a space heater that operates similarly to a typical unvented fireplace. The heater comprises a heater unit surrounded by a series of flues and baffles. Ambient air passes through the heater section, where it is combusted by a flame within a metal radiant element. The flow of the combustion air from the heater to the surrounding room is partially controlled by a deflecting choke surface, which accelerates expulsion of the heated air by increasing the air pressure at the choke. A second stream of air also freely flows behind the heater unit, through the flues and out the baffles. This second stream of air is warmed by thermal contact with the flues and thus also warms the room, but in addition it serves a cooling function, ensuring that the area immediately around the rear of the heater does not get too hot.
.io U.S. Patent No. 5054468 to Moon et al. describes an unvented fireplace assembly consisting of two chambers, namely a combustion chamber surrounded by a plenum chamber. Ambient air moves through the plenum chamber, warming by contact with the outside of the combustion chamber, before returning to the room in which the fireplace is located. Air is also pulled directly into the combustion chamber by a fan;
the heated combustion air is then expelled back into the room. U.S. Patent No.
5139011 to Moon describes a similar unvented fireplace with a pair of airflow paths.
Ambient air passes through a duct assembly around the combustion chamber, heating the air before returning it to the room. Combustion air is again pulled directly into the combustion chamber by a fan and heated before being returned to the room.
Each of these patents uses a dual intake system, which makes the system more complex, and makes it difficult to maintain a steady flow of air into both airflow pathways. If air moves relatively quickly into the combustion chamber, for example, there may not be sufficient plenum airflow to cool the area outside the combustion chamber. Further, in each of these cases, the combustion air and the plenum air are expelled into the room at different places and likely at different rates. The combustion air is hotter than the radiantly heated plenum air, which can lead to undesirable localized temperature variations.
U.S. Patent No. 5678534 to Fleming and U.S. Patent No. 5906197 to French each disclose a single-intake fireplace in which the incoming airflow is divided into several pathways, one flowing to the combustion chamber, and the others flowing to various convection pathways or plenum chambers surrounding the combustion chamber.
The air from the plenum or convection areas is then mixed with the combustion air
2 before being returned to the room. In order to minimize the combustion products being expelled into the room, the combustion air passes through a catalytic converter to convert any combustion products to carbon dioxide and water before the combustion air mixes with the plenum air and re-enters the room.
U.S. Patent No. 6425390 to Campbell and U.S. Patent No. 5,701,882 to Champion each disclose a gas fireplace in which combustion air is drawn directly into the combustion chamber while a second pathway for room air is provided in one or more plenum chambers surrounding the combustion chamber. Neither Campbell nor io Champion disclose a combustion chamber that is essentially sealed from the surrounding room, meaning that there is little to no control over the amount of air passing into the combustion chamber. This may adversely affect the appearance of the flame and the efficiency of burning within the combustion chamber.
It is therefore an object of this invention to provide an unvented gas fireplace that overcomes one or more of the disadvantages found in the prior art fireplaces referred to above.
SUMMARY OF 'THE INVENTION
The invention comprises an unvented gas fireplace in which air flow through a closed combustion chamber is controlled by means of a restriction in the air flow path through an outer plenum chamber surrounding the combustion chamber. The restriction in the air flow path through the plenum chamber causes a pressure differential between the plenum and combustion chambers. The relative increase in plenum chamber pressure forces air into the combustion chamber, where it is combusted and mixed with the air in the plenum chamber before the air mixture is exhausted into the surrounding room.
In one aspect, the invention comprises an unvented gas fireplace comprising a closed combustion chamber; a plenum outside of the combustion chamber, the plenum having an ambient air intake to receive air from a room in which the fireplace
U.S. Patent No. 6425390 to Campbell and U.S. Patent No. 5,701,882 to Champion each disclose a gas fireplace in which combustion air is drawn directly into the combustion chamber while a second pathway for room air is provided in one or more plenum chambers surrounding the combustion chamber. Neither Campbell nor io Champion disclose a combustion chamber that is essentially sealed from the surrounding room, meaning that there is little to no control over the amount of air passing into the combustion chamber. This may adversely affect the appearance of the flame and the efficiency of burning within the combustion chamber.
It is therefore an object of this invention to provide an unvented gas fireplace that overcomes one or more of the disadvantages found in the prior art fireplaces referred to above.
SUMMARY OF 'THE INVENTION
The invention comprises an unvented gas fireplace in which air flow through a closed combustion chamber is controlled by means of a restriction in the air flow path through an outer plenum chamber surrounding the combustion chamber. The restriction in the air flow path through the plenum chamber causes a pressure differential between the plenum and combustion chambers. The relative increase in plenum chamber pressure forces air into the combustion chamber, where it is combusted and mixed with the air in the plenum chamber before the air mixture is exhausted into the surrounding room.
In one aspect, the invention comprises an unvented gas fireplace comprising a closed combustion chamber; a plenum outside of the combustion chamber, the plenum having an ambient air intake to receive air from a room in which the fireplace
3 is located, and an ambient air outlet to exhaust air into the room; the plenum comprising a restriction, the restriction adapted to cause a positive air pressure differential between the plenum and the combustion chamber, upstream of the restriction; wherein the increase in air pressure forces air into the combustion chamber through a combustion air intake between the combustion chamber and the plenum; and wherein heated air is exhausted from the combustion chamber into the plenum through a combustion air outlet between the restriction and the ambient air outlet. The fireplace may further comprise at least one blower to pull air into the ambient inlet, and may comprise ducting between the ambient inlet and the blower.
In a further aspect of the invention, the heated air from the combustion chamber may be mixed with cool air in the plenum before exhausting the mixed air from the fireplace.
In another aspect, the invention comprises a method of heating a room with an unvented gas fireplace having a plenum outside of a closed combustion chamber, comprising the steps of receiving a flow of ambient air from the room into the plenum; restricting the flow of ambient air at a restriction in the plenum to create a positive air pressure differential between the plenum and the combustion chamber upstream of the restriction, and thereby force air from the plenum into the combustion chamber through a combustion air intake; exhausting heated air from the combustion chamber to the plenum downstream of the restriction; mixing the heated air with cool air within the plenum to form warm air; and exhausting the warm air to the room. In a further aspect, the method may comprise the additional step of blowing ambient air from the room into the plenum through an ambient air intake.
In yet another aspect, the invention comprises an unvented gas fireplace comprising a closed combustion chamber; a plenum outside of the combustion chamber for carrying air from an ambient air intake to an ambient air outlet; the plenum comprising a restriction, the restriction adapted to cause a positive air pressure differential between the plenum and the combustion chamber, upstream of the restriction; wherein the increase in air pressure forces air into the combustion chamber through a combustion air intake between the combustion chamber and the plenum; and wherein heated air is exhausted from the combustion chamber into the
In a further aspect of the invention, the heated air from the combustion chamber may be mixed with cool air in the plenum before exhausting the mixed air from the fireplace.
In another aspect, the invention comprises a method of heating a room with an unvented gas fireplace having a plenum outside of a closed combustion chamber, comprising the steps of receiving a flow of ambient air from the room into the plenum; restricting the flow of ambient air at a restriction in the plenum to create a positive air pressure differential between the plenum and the combustion chamber upstream of the restriction, and thereby force air from the plenum into the combustion chamber through a combustion air intake; exhausting heated air from the combustion chamber to the plenum downstream of the restriction; mixing the heated air with cool air within the plenum to form warm air; and exhausting the warm air to the room. In a further aspect, the method may comprise the additional step of blowing ambient air from the room into the plenum through an ambient air intake.
In yet another aspect, the invention comprises an unvented gas fireplace comprising a closed combustion chamber; a plenum outside of the combustion chamber for carrying air from an ambient air intake to an ambient air outlet; the plenum comprising a restriction, the restriction adapted to cause a positive air pressure differential between the plenum and the combustion chamber, upstream of the restriction; wherein the increase in air pressure forces air into the combustion chamber through a combustion air intake between the combustion chamber and the plenum; and wherein heated air is exhausted from the combustion chamber into the
4 plenum through a combustion air outlet between the restriction and the ambient air outlet.
The foregoing may cover only some of the aspects of the invention. Other aspects of the invention may be appreciated by reference to the following description of at least one preferred mode for carrying out the invention in terms of one or more examples. The following mode(s) for carrying out the invention is not a definition of the invention itself, but is only an example that embodies the inventive features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described by reference to the detailed description of the preferred embodiment and to the drawings thereof in which:
Fig. 1 is a side sectional schematic view of an unvented gas fireplace according to an embodiment of the invention;
Fig. 2 is a side sectional schematic view of an unvented gas fireplace according to another embodiment of the invention;
Fig 3 is a front view of the unvented gas fireplace of Fig. 2 with the combustion chamber removed;
Fig. 4 is a side sectional schematic view of a third embodiment of the invention straddling a wall of a building with a selectable diverter in a first position;
Fig. 5 is a side sectional schematic view of the third embodiment with the diverter in a second position;
Fig. 6 is a front perspective view of a stand-alone outdoor embodiment of the invention with the diverter in a first position;
Fig. 7 is a front perspective view of a stand-alone outdoor embodiment of the invention with the diverter in a second position; and, Fig. 8 is a rear perspective view of a stand-alone outdoor embodiment of the invention with the diverter in the second position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A first embodiment of the fireplace of the invention is shown in Fig. 1.
Fireplace 10 comprises a combustion chamber 12 at least partially within an outer or plenum to chamber 14. Combustion chamber 12 is closed with respect to the room in which the fireplace 10 is located, in that combustion air intake 16 and combustion air outlet 18 of combustion chamber 12 are not in direct communication with the surrounding room. Rather, combustion air intake 16 receives air only from plenum 14 and combustion air outlet 18 exhausts only into plenum 14. Panels 20 are provided on is one or more sides of combustion chamber 12; these panels may be glass or any other suitable transparent material to permit viewing of the flame 30 within the combustion chamber 12, or may be metal or any other suitable opaque material if such viewing is not required.
20 Air from the surrounding room accesses fireplace 10 through ambient air intake 22 in the plenum 14, while air is exhausted from fireplace 10 through ambient air outlet 24 of plenum 14. Blower 26 may be used at or near ambient air intake 22 to draw air into plenum 14.
25 Under startup conditions, air entering the fireplace 10 through ambient air intake 22 will preferentially remain in plenum 14, flowing along path 28, without a great deal of air entering combustion air intake 16, because the size of path 28 is much greater than that of combustion air intake 16. However, path 28 is provided with restriction 32, a relatively narrow section of path 28, which restricts the air flow through path 28.
30 This backs up the air between restriction 32 and blower 26, causing a positive pressure differential between plenum 14 and combustion chamber 12, upstream of the restriction. The pressure differential forces air in plenum 14 to enter combustion chamber 12 through combustion air intake 16, which is preferably located below the flame 30, and which may take the form of one or more openings arranged in any suitable pattern. The air is heated within combustion chamber 12, and rises above the flame, where it escapes through combustion air outlet 18, which may also take the form of one or more openings arranged in any suitable pattern. The pressure differential between plenum 14 and combustion chamber 12 therefore helps to maintain the pressure and air velocity within combustion chamber 12, by forcing air through the chamber 12 without over-pressurizing it.
io Restriction 32 is shown in Fig. 1 as being in an upper part of path 28, but it will be understood that it may be located anywhere within plenum 14 along path 28 between combustion air intake 16 and combustion air outlet 18.
Air entering combustion chamber 12 assists in the combustion reaction to create flame 30 and hot air, which exits the combustion chamber 12 at combustion air outlet 18. When the hot air exits combustion chamber 12 into path 28 in plenum 14, it may exhaust directly into the room or to the outside, or it may mix with relatively cool air that has flowed along path 28 through restriction 32. The combination of hot and cool air flows creates a warm air flow that exhausts to the surrounding room or to the outside at ambient air outlet 24. Combustion air outlet 18 is shown as being at the top of combustion chamber 12, which may be preferred because the heated air will naturally rise towards the combustion air outlet 18. However, it will be understood that combustion air outlet 18 may appear anywhere in path 28 between restriction 32 and ambient air outlet 24. Factors such as the preferred time available for the heated air to mix with the cool air flowing through path 28 may influence the exact location of combustion air outlet 18. It will also be understood that path 28 can be of any preferred shape and length, such that ambient air outlet 24 terminates at any desired point, such as at the top of the fireplace 10 (as shown in Fig. 1) or anywhere along the bottom or side of the fireplace 10, thus providing a stream of warm air to the surrounding room or to the outside at any desired point.
Another embodiment of the unvented fireplace 10 of the invention is shown in Figs. 2 and 3. This embodiment works essentially in the same manner as the embodiment described above, although in this embodiment, blower 26 of Fig. 1 is replaced by one or more backward inclined blowers 34. Further, blower 34 (or an equivalent fan or blower assembly) may be placed anywhere suitable within path 28, and additional ducting 36 may be used as necessary between ambient air intake 22 and blower 34.
Blower 34 draws air into plenum 14 through ducting 36, and distributes it throughout the plenum 14. Restriction 32 causes an increase in air pressure in the plenum 14, forcing air from plenum 14 through combustion air intake 16 (which may take the form of one or more openings arranged in any suitable pattern), and into combustion chamber 12. The combustion air rises towards the top of combustion chamber 12 as it is heated. The air then passes out of combustion chamber 12, where it may be io exhausted directly to the ambient room in which the fireplace is located or to the outside, but preferably it is exhausted into path 28 of plenum 14 via combustion air outlet 18. The heated combustion air mixes with cool air that has flowed along path 28 past restriction 32, creating a warm air mixture that may be vented through ambient air outlet 24. Again, it will be understood that path 28 can be of any preferred shape, such that ambient air outlet 24 terminates at any desired point along the top, bottom or side of the fireplace 10, thus providing a stream of warm air to the surrounding room or to the outside wherever it is preferred.
A third embodiment is shown in Figs. 4 and 5. The fireplace according to this embodiment is provided in an external wall 40 of a building such that one side 42 of the unit faces the outside 44 of the building and the opposite side 46 of the unit faces the interior 48 of a room of the building. Air is drawn into the unit by intake opening 50 on the outdoor side of the unit. Incoming air is drawn by blower 52 into passageway 54. A portion of the air in passageway 54 passes into the combustion chamber at 56 and a portion is driven past restriction 58.to mix with air and combustion gases exiting the combustion chamber at chamber outlet 60. The combined air flow is directed down a passageway 62 that is preferably formed of two spaced transparent panels 64, 66 allowing viewing into the firebox from the outside of the building as well as from the inside of the building through two spaced transparent panels 68, 70. A diverter 72 is operable by a user to pivot between a first position shown in Fig. 4 and a second position shown in Fig. 5. by means of a knob (not shown).
In the first position shown in Fig 4, the combined combustion and excess drawn air flow is directed to the exterior of the building by outlet 74. In the second position shown in Fig. 5, the combined air flow is directed to outlet 76 that exhausts to the inside of the building.
In yet a further embodiment, shown in Fig. 6, the fireplace is provided as a standalone outdoor unit 80 rather than straddling the exterior wall of a building.
According to the preference of the user, the relatively warm exhaust air may be directed to one side or the other of the unit, for example to accommodate where io people may be seated around the fireplace. In Fig. 6, the diverter 72 is in the first position corresponding to Fig. 4 in which the air intakes 82, 84 are on the same side as the air outlet 86. Fig. 7 illustrates the standalone outdoor unit wherein the diverter is in the second position corresponding to Fig. 5 in which the air is outlet at 88 to the opposite side of the unit. This allows the user to select the direction of exhaust of relatively warm air depending on the location of the standalone unit, the location of persons seated around the unit and the ambient outdoor temperature. Fig. 8 shows the outlets at the rear of the standalone unit with the diverter in the second position.
As in the embodiment of Figs. 4 and 5, the panels forming the air passageways along the sides of the unit are transparent to allow viewing of the firebox from either the front or the back of the unit 80.
It will be appreciated by those skilled in the art that the preferred embodiment has been described in some detail but that certain modifications may be practiced without departing from the principles of the invention.
The foregoing may cover only some of the aspects of the invention. Other aspects of the invention may be appreciated by reference to the following description of at least one preferred mode for carrying out the invention in terms of one or more examples. The following mode(s) for carrying out the invention is not a definition of the invention itself, but is only an example that embodies the inventive features of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will be described by reference to the detailed description of the preferred embodiment and to the drawings thereof in which:
Fig. 1 is a side sectional schematic view of an unvented gas fireplace according to an embodiment of the invention;
Fig. 2 is a side sectional schematic view of an unvented gas fireplace according to another embodiment of the invention;
Fig 3 is a front view of the unvented gas fireplace of Fig. 2 with the combustion chamber removed;
Fig. 4 is a side sectional schematic view of a third embodiment of the invention straddling a wall of a building with a selectable diverter in a first position;
Fig. 5 is a side sectional schematic view of the third embodiment with the diverter in a second position;
Fig. 6 is a front perspective view of a stand-alone outdoor embodiment of the invention with the diverter in a first position;
Fig. 7 is a front perspective view of a stand-alone outdoor embodiment of the invention with the diverter in a second position; and, Fig. 8 is a rear perspective view of a stand-alone outdoor embodiment of the invention with the diverter in the second position.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
A first embodiment of the fireplace of the invention is shown in Fig. 1.
Fireplace 10 comprises a combustion chamber 12 at least partially within an outer or plenum to chamber 14. Combustion chamber 12 is closed with respect to the room in which the fireplace 10 is located, in that combustion air intake 16 and combustion air outlet 18 of combustion chamber 12 are not in direct communication with the surrounding room. Rather, combustion air intake 16 receives air only from plenum 14 and combustion air outlet 18 exhausts only into plenum 14. Panels 20 are provided on is one or more sides of combustion chamber 12; these panels may be glass or any other suitable transparent material to permit viewing of the flame 30 within the combustion chamber 12, or may be metal or any other suitable opaque material if such viewing is not required.
20 Air from the surrounding room accesses fireplace 10 through ambient air intake 22 in the plenum 14, while air is exhausted from fireplace 10 through ambient air outlet 24 of plenum 14. Blower 26 may be used at or near ambient air intake 22 to draw air into plenum 14.
25 Under startup conditions, air entering the fireplace 10 through ambient air intake 22 will preferentially remain in plenum 14, flowing along path 28, without a great deal of air entering combustion air intake 16, because the size of path 28 is much greater than that of combustion air intake 16. However, path 28 is provided with restriction 32, a relatively narrow section of path 28, which restricts the air flow through path 28.
30 This backs up the air between restriction 32 and blower 26, causing a positive pressure differential between plenum 14 and combustion chamber 12, upstream of the restriction. The pressure differential forces air in plenum 14 to enter combustion chamber 12 through combustion air intake 16, which is preferably located below the flame 30, and which may take the form of one or more openings arranged in any suitable pattern. The air is heated within combustion chamber 12, and rises above the flame, where it escapes through combustion air outlet 18, which may also take the form of one or more openings arranged in any suitable pattern. The pressure differential between plenum 14 and combustion chamber 12 therefore helps to maintain the pressure and air velocity within combustion chamber 12, by forcing air through the chamber 12 without over-pressurizing it.
io Restriction 32 is shown in Fig. 1 as being in an upper part of path 28, but it will be understood that it may be located anywhere within plenum 14 along path 28 between combustion air intake 16 and combustion air outlet 18.
Air entering combustion chamber 12 assists in the combustion reaction to create flame 30 and hot air, which exits the combustion chamber 12 at combustion air outlet 18. When the hot air exits combustion chamber 12 into path 28 in plenum 14, it may exhaust directly into the room or to the outside, or it may mix with relatively cool air that has flowed along path 28 through restriction 32. The combination of hot and cool air flows creates a warm air flow that exhausts to the surrounding room or to the outside at ambient air outlet 24. Combustion air outlet 18 is shown as being at the top of combustion chamber 12, which may be preferred because the heated air will naturally rise towards the combustion air outlet 18. However, it will be understood that combustion air outlet 18 may appear anywhere in path 28 between restriction 32 and ambient air outlet 24. Factors such as the preferred time available for the heated air to mix with the cool air flowing through path 28 may influence the exact location of combustion air outlet 18. It will also be understood that path 28 can be of any preferred shape and length, such that ambient air outlet 24 terminates at any desired point, such as at the top of the fireplace 10 (as shown in Fig. 1) or anywhere along the bottom or side of the fireplace 10, thus providing a stream of warm air to the surrounding room or to the outside at any desired point.
Another embodiment of the unvented fireplace 10 of the invention is shown in Figs. 2 and 3. This embodiment works essentially in the same manner as the embodiment described above, although in this embodiment, blower 26 of Fig. 1 is replaced by one or more backward inclined blowers 34. Further, blower 34 (or an equivalent fan or blower assembly) may be placed anywhere suitable within path 28, and additional ducting 36 may be used as necessary between ambient air intake 22 and blower 34.
Blower 34 draws air into plenum 14 through ducting 36, and distributes it throughout the plenum 14. Restriction 32 causes an increase in air pressure in the plenum 14, forcing air from plenum 14 through combustion air intake 16 (which may take the form of one or more openings arranged in any suitable pattern), and into combustion chamber 12. The combustion air rises towards the top of combustion chamber 12 as it is heated. The air then passes out of combustion chamber 12, where it may be io exhausted directly to the ambient room in which the fireplace is located or to the outside, but preferably it is exhausted into path 28 of plenum 14 via combustion air outlet 18. The heated combustion air mixes with cool air that has flowed along path 28 past restriction 32, creating a warm air mixture that may be vented through ambient air outlet 24. Again, it will be understood that path 28 can be of any preferred shape, such that ambient air outlet 24 terminates at any desired point along the top, bottom or side of the fireplace 10, thus providing a stream of warm air to the surrounding room or to the outside wherever it is preferred.
A third embodiment is shown in Figs. 4 and 5. The fireplace according to this embodiment is provided in an external wall 40 of a building such that one side 42 of the unit faces the outside 44 of the building and the opposite side 46 of the unit faces the interior 48 of a room of the building. Air is drawn into the unit by intake opening 50 on the outdoor side of the unit. Incoming air is drawn by blower 52 into passageway 54. A portion of the air in passageway 54 passes into the combustion chamber at 56 and a portion is driven past restriction 58.to mix with air and combustion gases exiting the combustion chamber at chamber outlet 60. The combined air flow is directed down a passageway 62 that is preferably formed of two spaced transparent panels 64, 66 allowing viewing into the firebox from the outside of the building as well as from the inside of the building through two spaced transparent panels 68, 70. A diverter 72 is operable by a user to pivot between a first position shown in Fig. 4 and a second position shown in Fig. 5. by means of a knob (not shown).
In the first position shown in Fig 4, the combined combustion and excess drawn air flow is directed to the exterior of the building by outlet 74. In the second position shown in Fig. 5, the combined air flow is directed to outlet 76 that exhausts to the inside of the building.
In yet a further embodiment, shown in Fig. 6, the fireplace is provided as a standalone outdoor unit 80 rather than straddling the exterior wall of a building.
According to the preference of the user, the relatively warm exhaust air may be directed to one side or the other of the unit, for example to accommodate where io people may be seated around the fireplace. In Fig. 6, the diverter 72 is in the first position corresponding to Fig. 4 in which the air intakes 82, 84 are on the same side as the air outlet 86. Fig. 7 illustrates the standalone outdoor unit wherein the diverter is in the second position corresponding to Fig. 5 in which the air is outlet at 88 to the opposite side of the unit. This allows the user to select the direction of exhaust of relatively warm air depending on the location of the standalone unit, the location of persons seated around the unit and the ambient outdoor temperature. Fig. 8 shows the outlets at the rear of the standalone unit with the diverter in the second position.
As in the embodiment of Figs. 4 and 5, the panels forming the air passageways along the sides of the unit are transparent to allow viewing of the firebox from either the front or the back of the unit 80.
It will be appreciated by those skilled in the art that the preferred embodiment has been described in some detail but that certain modifications may be practiced without departing from the principles of the invention.
Claims (6)
1. An unvented gas fireplace comprising:
a substantially closed combustion chamber;
a plenum for circulating air outside of and around said combustion chamber, said plenum having an ambient air intake to receive air from a room in which the fireplace is located and an air outlet to exhaust air into said room;
a fan for drawing air from said room and for pressurizing said plenum;
said combustion chamber comprising an air inlet from said plenum into said combustion chamber, said air inlet downstream from said fan, and an air outlet from said combustion chamber into said plenum;
said plenum comprising a restriction located between said combustion chamber air inlet and said combustion air outlet, said fan and said restriction cooperating to cause a positive air pressure differential between said plenum and said combustion chamber, upstream of said restriction and at said combustion chamber air inlet, whereby to force a portion of the air in said plenum to enter said air inlet from said plenum to said combustion chamber while allowing the balance of the air in said plenum to proceed to said air outlet;
and wherein heated air is exhausted from said combustion chamber into said plenum through said combustion air outlet between said restriction and said air outlet.
a substantially closed combustion chamber;
a plenum for circulating air outside of and around said combustion chamber, said plenum having an ambient air intake to receive air from a room in which the fireplace is located and an air outlet to exhaust air into said room;
a fan for drawing air from said room and for pressurizing said plenum;
said combustion chamber comprising an air inlet from said plenum into said combustion chamber, said air inlet downstream from said fan, and an air outlet from said combustion chamber into said plenum;
said plenum comprising a restriction located between said combustion chamber air inlet and said combustion air outlet, said fan and said restriction cooperating to cause a positive air pressure differential between said plenum and said combustion chamber, upstream of said restriction and at said combustion chamber air inlet, whereby to force a portion of the air in said plenum to enter said air inlet from said plenum to said combustion chamber while allowing the balance of the air in said plenum to proceed to said air outlet;
and wherein heated air is exhausted from said combustion chamber into said plenum through said combustion air outlet between said restriction and said air outlet.
2. The gas fireplace of claim 1 further comprising at least one blower to pull air into said ambient inlet.
3. The gas fireplace of claim 2 further comprising ducting between said ambient inlet and said blower.
4. The gas fireplace of claim 1 wherein said heated air is mixed with cool air in said plenum before exhausting the mixed air from said fireplace.
5. A method of heating a room with an unvented gas fireplace having a substantially closed combustion chamber, and a plenum for circulating air outside of and around said combustion chamber, said method comprising the steps of:
receiving from a fan, a flow of ambient air from said room into said plenum and thereby pressurizing said plenum;
restricting said flow of ambient air at a restriction in said plenum between a combustion air intake from said plenum, said combustion air intake being downstream from said fan, and a combustion air outlet into said plenum to create a positive air pressure differential between said plenum and said combustion chamber upstream of said restriction, and thereby force air from said plenum into said combustion chamber through said combustion air intake;
exhausting heated air from said combustion chamber to said plenum through said combustion air outlet downstream of said restriction;
mixing said heated air with cool air within said plenum to form warm air;
and exhausting said warm air to said room.
receiving from a fan, a flow of ambient air from said room into said plenum and thereby pressurizing said plenum;
restricting said flow of ambient air at a restriction in said plenum between a combustion air intake from said plenum, said combustion air intake being downstream from said fan, and a combustion air outlet into said plenum to create a positive air pressure differential between said plenum and said combustion chamber upstream of said restriction, and thereby force air from said plenum into said combustion chamber through said combustion air intake;
exhausting heated air from said combustion chamber to said plenum through said combustion air outlet downstream of said restriction;
mixing said heated air with cool air within said plenum to form warm air;
and exhausting said warm air to said room.
6. The method of claim 5 further comprising the step of blowing ambient air from said room into said plenum through an ambient air intake.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2736458A CA2736458C (en) | 2011-02-01 | 2011-04-06 | Unvented gas fireplace |
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US13/018,720 US8567387B2 (en) | 2011-02-01 | 2011-02-01 | Unvented gas fireplace |
| US13/018,720 | 2011-02-01 | ||
| CA2730807A CA2730807A1 (en) | 2011-02-01 | 2011-02-02 | Unvented gas fireplace |
| CA2,730,807 | 2011-02-02 | ||
| US13/081,209 US20120192853A1 (en) | 2011-02-01 | 2011-04-06 | Unvented gas fireplace |
| CA2736458A CA2736458C (en) | 2011-02-01 | 2011-04-06 | Unvented gas fireplace |
| US13/081,209 | 2011-04-06 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2736458A1 CA2736458A1 (en) | 2012-08-01 |
| CA2736458C true CA2736458C (en) | 2016-06-28 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2736458A Active CA2736458C (en) | 2011-02-01 | 2011-04-06 | Unvented gas fireplace |
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| Country | Link |
|---|---|
| CA (1) | CA2736458C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2813871C (en) | 2013-04-19 | 2016-05-31 | Canadian Heating Products Inc. | Cooling system for gas fireplace |
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2011
- 2011-04-06 CA CA2736458A patent/CA2736458C/en active Active
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| Publication number | Publication date |
|---|---|
| CA2736458A1 (en) | 2012-08-01 |
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