Stoves and furnaces – Fireplaces or accessories – Fluid fuel
Reexamination Certificate
1999-01-22
2001-07-10
Price, Carl D. (Department: 3743)
Stoves and furnaces
Fireplaces or accessories
Fluid fuel
C126S502000, C126S504000, C126S084000, C431S125000, C237S047000, C237S046000, C454S239000, C454S256000
Reexamination Certificate
active
06257230
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to gas fireplaces and heaters and more particularly to a room exhausting gas fireplace in which the amount of exhaust products, heat and moisture vented into a room are controlled without sacrifice of flame appearance.
BACKGROUND OF THE INVENTION
In a gas fireplace, a combustible gas, e.g., natural gas or propane, is mixed with a source of oxygen, e.g., air, and burned. In a ventless gas fireplace, air is drawn into the combustion chamber or firebox of the fireplace typically from the room in which the fireplace is situated, and hot exhaust gases containing combustion products including carbon monoxide, carbon dioxide, nitrogen dioxide and water are vented directly into the room.
In gas fireplaces, it is desirable to adjust the air/gas ratio to create a bright yellow flame which mimics the flame produced in a wood burning fireplace. Such a flame, however, tends to produce an undesirably high level of emission products. This is particularly troublesome in a ventless fireplace which has strict emission requirements. For example, the ANSI standard for carbon monoxide emission is no more than 200 ppm. The ANSI standard for nitrogen dioxide is no more than 20 ppm. To control these emissions, an operator typically uses a clean burning blue flame, sacrificing the more aesthetically pleasing yellow flame.
Another problem associated with the use of a ventless fireplace is the generation of too much water vapor which is vented directly into a room. This not only creates high humidity, but if the fireplace is used frequently, there is a possibility of moisture condensation on the walls or other objects within the room. Yet another problem associated with ventless fireplaces is the generation of too much heat.
One method for controlling the amount of carbon monoxide and nitrogen dioxide in the exhaust of a ventless fireplace is through the use of a catalytic converter. Such a use is described in U.S. patent application Ser. No. 08/509,426 and patent application entitled “GAS FIREPLACE”, filed Oct. 1, 1996, naming French, et al. as inventors. While this method is useful in controlling carbon monoxide and nitrogen dioxide levels in the exhaust, it does nothing to control the amount of moisture in the exhaust or the amount of heat generated by the fireplace. Currently, the only way to control the amount of heat and moisture generated by a ventless fireplace and vented into a room is to reduce the amount of combustion, i.e., reduce the size or quality of the flame or shut off the fireplace. Reduction or elimination of the flame diminishes the aesthetic look and appeal for which the fireplace was designed.
There is therefore, a need for a means by which an operator can control the amount of heat and moisture vented into a room by a ventless gas fireplace.
SUMMARY OF THE INVENTION
The present invention provides a factory built fireplace in which the amount of heat exhausted from the fireplace into the room in which the fireplace is located may be controlled without changing the size or color of the flame within the fireplace. The gas fireplace comprises a housing and a firebox within the housing. A plenum is provided between the firebox and the housing from which heated gases are vented into the room in which the fireplace is located. First and second openings are provided through the housing wall into the plenum. A first vent pipe is attached to the housing in surrounding relation to the first opening so that the interior of the first vent pipe is in communication with the plenum. A second vent pipe is attached to the housing in surrounding relationship to the second opening so that the interior of the second vent pipe is also in communication with the plenum. The second opening is downstream from the first opening. When the gas fireplace is installed in a room, the vent pipes extend through a wall of the room, preferably an exterior wall of the room. The first and second openings and vent pipes are located so that heated air may be withdrawn from the plenum through the first vent pipe and cool air may be introduced into the plenum through the second vent pipe. Means are provided for controlling the amount of heated air withdrawn from the plenum and cool air introduced into the plenum through the first and second vent pipes.
A preferred means for controlling the amount of heated air withdrawn from the plenum through the first vent pipe and cool air introduced into the plenum through the second vent pipe comprises means for reversibly blocking the vent pipes. A particularly preferred reversibly blocking means comprises at least one door which is movable between a closed position blocking passage of air through at least one and preferably both vent pipes and an open position wherein passage of air through the vent pipes is minimally restricted. Means are also provided for controllably moving the door or doors between its open and closed positions. The door may be movable in any fashion, e.g., slidably movable, hingedly movable or rotatably movable. Preferred means for controllably moving the door comprises a movable handle and a linkage which is connected at one end to the handle and at the other end to the door whereby movement of the handle results in movement of the door. Alternatively, movement of the door or doors may be controlled by an electric motor or the like. The electric motor may be activated by electrical switches accessible to an operator or, for example, by a thermostat. In yet another embodiment of the invention, movement of the door is controlled automatically by a thermally responsive mechanism such as a bi-metal spring.
In a preferred embodiment, the fireplace further comprises means for preventing cool air entering the plenum through the second vent pipe from passing into the firebox or combustion chamber. In one embodiment of the invention, such means comprises a baffle which extends across at least a portion of the plenum between the first and second openings preventing cool air entering the plenum from the second opening from flowing in an upstream direction toward the opening into the firebox or combustion chamber. Alternatively, such means may comprise a fan located within the plenum which directs air in a downstream direction thus preventing cool air entering the plenum through the second vent pipe from flowing upstream toward the fire opening into the firebox or combustion chamber.
In another aspect of the invention, there is provided an adapter for a ventless gas fireplace. The adapter comprises first and second vent pipes which are attachable to the housing in surrounding relation to first and second openings made in the housing. Each of the vent pipes are sufficient length to extend from the fireplace through a selected wall of the room in which the fireplace is located. Means are provided for controllably restricting the flow of air through at least one and preferably both of the first and second vent pipes. A particularly preferred means for controllably restricting the flow of air through the first and second vent pipes comprises a pair of baffles rotatably mounted within each of the first and second vent pipes. The baffles are mounted on a rod which extends through the first and second vent pipes whereby rotational movement of the rod results in rotational movement of the baffles within the vent pipes. A linkage and handle are connected to the rod such that movement of the handle results in rotational movement of the rod and baffles. The baffles are movable between a closed position or when the baffles are transverse to the access of the vent pipes and an open position wherein the plane of the baffles is generally along the access of the vent pipes. Preferably, means are provided for preventing the flow of air through the first vent pipe into the plenum and for preventing the flow of air through the second vent pipe out of the plenum.
REFERENCES:
patent: 1365912 (1921-01-01), Greene
patent: 2877834 (1959-03-01), Campbell
patent: 4185612 (1980-01-01), Briner et al.
patent: 4609346 (1986-09-01), Siccardi
patent: 52
Barudi Samir E.
Kelly Andrea D.
Kelly John R.
Mitchell Rodger Duke
Christie Parker & Hale LLP
Kelly Andrea D.
Price Carl D.
Superior Fireplace Company
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