Since the time that central heating systems became the most common method of heating domestic living quarters, fireplaces have been used primarily for esthetic effects. With the recent shortages and emphasis on conservation of fossil fuels, the fireplace has again come into prominence as a space heating appliance.
In order to optimize heating efficiency, it is desirable that oxygen supporting combustion should be provided by air drawn from outside the room or space to be heated. In many prior devices, when air from the room is drawn into the firebox by the natural draft of combustion products passing up the flue, cold outside air must be drawn into the room through whatever path is available. Consequently, air is often drawn into the house through doors, windows, and other openings, thereby defeating the heating function of the fireplace.
In relatively recent years, the so-called "factory built" fireplaces have come into prominent usage. Such fireplaces are constructed chiefly of sheet metal and are shipped in a condition ready for installation in a dwelling, as opposed to the traditional masonry fireplace which is essentially an integral part of the sturcture in which it is built. The factory built fireplaces generally require that passages be provided for flow of air under the hearth and about other areas of the fireplace structure subject to direct heat in order to avoid the possibility of overheating and igniting flammable portions of the building in which the fireplace is installed. For the reasons previously mentioned, it is desirable that air from outside the room or space to be heated be utilized for purposes of providing a moving layer of cooling air between elements of the fireplace and adjacent portions of the structure in which it is installed.
It is a principal object of the present invention to provide novel and improved apparatus for supplying air to a fireplace structure within a room from a source outside the room, while at the same time preventing exposure of the room to the cooler temperature of the outside air.
Another object of the invention is to provide means for supplying air both for supporting combustion and for preventing an overheating condition in a factory-built fireplace from a source outside the room in which the fireplace is installed.
A further object is to provide air supply means, drawn from an outside source, for supplying combustion supporting air to an open fireplace in a relatively evenly distributed air curtain across the front of the firebox.
A further object of the present invention is the provision of baffle means which separates outside air into two areas so as to facilitate partial cooling in the vicinity of the baffle.
A further object of the present invention is the utilization of a baffle means which provides protection against hot particles falling into the base of the air vent tubes.
A further object of the invention is the provision of a device which can be installed after the fireplace is in position and with a minimum of structural changes.
A further object of the present invention is the provision of a device which has means for easy access to the air inlet damper for repair and maintenance.
A further object of the present invention is a device which includes a grill cover designed to withstand the impact of a wood log which may be dropped when the fireplace is being fueled.
A further object of the present invention is the provision of a device which permits outside air to enter the fireplace through openings beneath the glass door frame whenever a glass door frame is used with the fireplace.
Other objects will in part be apparent and will in part appear hereinafter.