Abstract:
A flexible tubular body with annular ribs defining an expanded heating surface and a pair of integral clamps constitute a heat exchanger that is mountable to a fireplace lintel. Opposite ends of the tubular body, which are exposed at oppposite sides of the fireplace opening, are provided with deflection grates for directing air flow. A panel extends across the fireplace opening at an upper region thereof and constitutes a smoke deflector. A thermostatically controlled, variable speed blower is contained within the tubular body for drawing cool air from the room and for exhausting heated air into the room, the cool air being heated within the tubular body by a fire in the fireplace.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to heating devices and more particularly to fireplace heaters. 
     2. Description of the Prior Art 
     It is well known that the heating efficiency of an open fire in a fireplce is extremely low. Most of the heat generated by the fire passes up the flue and only a small percentage of the heat generated passes into the room. Various devices, which have been designed to utilize the intense heat generated within the fireplace containing an open fire, have been introduced with varying degrees of success. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a heat exchanger for use with an existing fireplace which will greatly increase the heating efficiency of the fireplace. The heat exchanger includes a flexible tubular body with annular ribs that define an expanded heating surface as well as supporting members. A pair of clamps at opposite ends of the tubular body are provided for mounting the heat exchanger to a fireplace lintel, the tubular body being disposed horizontally at an upper region of the fireplace chamber with the tubular body ends exposed at opposite sides of the fireplace opening, one of the ends defining an inlet port and the other end defining an outlet port. A panel which extends across the entire fireplace opening at an upper region thereof constitutes a smoke deflector, the ends of the tubular body project through holes formed in the panel. A deflection grate is fitted over each end of the tubular body for directing air flow. A thermostatically controlled, variable speed blower is housed within the tubular body adjacent the inlet port for drawing cool air from the room and for exhausting heated air through the outlet port into the room, the cool air being heated as it passes within the tubular body by an open fire in the fireplace. 
     Other objects of the present invention will in part be obvious and will in part appear hereinafter. 
     The invention accordingly comprises the devices, together with their parts, elements and interrelationships, that are exemplified in the following disclosure, the scope of which will be indicated in the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A fuller understanding of the nature and objects of the present invention will become apparent upon consideration of the following detailed description taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a heat exchanger embodying the invention in a fireplace; 
     FIG. 2 is a sectional view taken along the lines 2--2 in FIG. 1; 
     FIG. 3 is a top plan view of the heat exchanger of FIG. 1; 
     FIG. 4 is a schematic diagram; and 
     FIG. 5 is a sectional view taken along the lines 5--5 of FIG. 3. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, particularly FIGS. 1 and 2, there is shown a fireplace 10 having an opening 12 in which there is mounted a heat exchanger 14 embodying the present invention. Heat exchanger 14 is mounted to a lintel 16 which extends across the top of opening 12. Heat exchanger 14 includes a continuous flexible tubular body 18 having annular ribs 20 which constitute an expanded heating surface. Tubular body 18 is composed of a metal that will withstand a temperature range of 1500° F to 2500° F without exhibiting any deleterious effects, for example stainless steel, steel or aluminum. In the preferred embodiment, tubular body 18 is composed of stainless steel and withstands temperatures of 2000° F. The diameter of tubular body 18 typically is in the range of 4 inches to 8 inches and preferably 6 inches. The length of tubular body 18 is in the range of 2 feet to 8 feet and typically is 4 feet for standard fireplace openings. Typically, the wall thickness of tubular body 18 is in the range of 0.004 inch to 0.25 inch and preferably 0.12 inch. The peak to valley distance of ribs 20 typically is in the range of 0.015 inch to 0.5 inch and preferably 0.125 inch. 
     A pair of bands 22 and 24 are placed about opposite end margins of tubular body 18 for holding a pair of clamps 26 and 28, respectively. Each band 22 and 24 is provided with quick release latches 30 and 32, each latch having locked and unlocked positions. When the latch is in its unlocked position, its associated band is slidable and rotatable with respect to tubular body 18. When the latch is in its locked position, its associated band is fixed against movement relative to tubular body 18. 
     As best shown in FIG. 5, clamp 26 has a substantially C-shaped profile in right cross section and includes a medial body 34 and a pair of legs 36, 38 which extend upwardly from opposite ends of body 34. Leg 38, the rear leg, is formed with a threaded hole 40 in which a screw 42 having a wind head 43 is turned. Clamp 28 has a sustantially C-shaped profile in right cross section and includes a medial body 44 and a pair of legs 46, 48 which extend upwardly from opposite ends of body 44. Leg 48, the rear leg, is formed with a threaded hole 50 in which a screw 52 having a wing head 54 is turned. 
     As previously indicated, heat exchanger 14 is mounted to lintel 16 of fireplace 10. Tubular body 18 is bent into a substantially U-shaped configuration and inserted into opening 12. Typically, the radius of curvature is in the range of 2 inches to 10 inches. As illustrated in FIG. 3, the bend of tubular body 18 is such that the inner most portion is near the rear wall of the fireplace and the ends of the tubular body are flush with the face of the fireplace. Latches 30 and 32 are placed in their unlocked positions, and screws 42 and 52 are loosened. Tubular body 18 is lifted to the upper portion of opening 12. Bands 22 and 24 are moved relative to tubular body 18 until clamps 26 and 28 are in registration with lintel 16 at opposite ends of opening 12. Clamps 26 and 28 are positioned so that they fit into lintel 16. That is, legs 36 and 46, the forward legs, are positioned at the front face of the fireplace and rearward legs 38 and 48 are at the back side of the lintel. Screws 42 and 52 are turned into their respective threaded hole for securing the clamps to the lintel. Then, latches 30 and 32 are locked for clamping tubular body 18 to lintel 16. Tubular body 18 is sufficiently flexible to be readily bent into the desired configuration and is sufficiently rigid to be supported in a substantially horizontal plane when the body ends are clamped to the fireplace lintel. Annular ribs 20 constitute stiffeners which provide support for tubular body 18. 
     Preferably, heat exchanger 14 includes a panel 56 which constitutes a smoke deflector and extends across opening 12. Panel 56 has a substantially L-shaped profile in right cross section and includes a skirt 58 and a flange 60. Skirt 58 is formed with a pair of openings 62, 64 which are in registration with the ends of tubular body 18. Flange 60 is formed with a pair of slots 66, 68 which are in registration with forward legs 36, 46, respectively. Smoke deflector 56 is mounted to lintel 16 by inserting legs 36 and 46 through slots 66, 68, the ends of tubular body 18 projecting through openings 62, 64. When clamps 26 and 28 are secured to lintel 16, flange 60 is sandwiched between the medial body of each clamp and the lintel. In the illustrated embodiment, openings 62 and 64 have a substantially semi-circular profile. Preferably, skirt 58 extends to the midpoint of tubular body 18 and spans the width of opening 12, the ends of the skirt in contact with the sides of opening 12. 
     The exposed ends of tubular body 18 are covered with caps 70 and 72 which are composed of a metal such as stainless steel, steel or aluminum and constitute air deflectors. Cap 70 includes a face plate 74 and an annular flange 76. Face plate 74 includes a plurality of interwoven strips 78 that define a mesh configuration. Annular flange 76 is configured to be snugly received about one end of tubular body 18. Cap 72 includes a face plate 80 and an annular flange 82. Face plate 80 includes a plurality of interwoven strips 84 that define a mesh configuration. Annular flange 76 is configured to be snugly received about the other end of tubular body 18. 
     In the illustrated embodiment, by way of example, the end of tubular body 18 to which cap 70 is attached constitutes an inlet port through which cool air enters and the end of tubular body to which cap 72 is attached constitutes an outlet port through which warm air exits. Cool air is drawn into the inlet port by means of a blower 86 which inclues a driver 88, for example a brush or brushless shaded pole AC motor, and a blade assembly 90. Motor 88 is mounted to the interior surface of tubular member 18 by means of a bracket 92 attached to the motor housing, blade assembly 90 facing cap 70. Blade assembly 90, for example ten blades assemblage, is operative to draw air into the inlet port. The amount of air drawn into the inlet port is governed by the speed at which blade assembly 90 is rotated by motor 88. A controller 94, for example a 0-350 ohm rheostat, regulates the speed of motor 88 and hence the flow of cool air into the inlet port. Rheostat 94 includes a shaft 96 which is connected to a wiper arm 98 of a resistor 100. Shaft 96 is received through an opening in face plate 74 and secured thereto by means of fasteners 102, 104, for example nuts that are turned onto a threaded sleeve 106 of the rheostat. The end of shaft 96 projects outwardly of cap 70, the body of rheostat 94 being disposed within tubular body 18. A knob 105 is mounted to the projecting end of shaft 96 for adjusting rheostat 94. 
     A sensor 106, for example a snap action bimetallic thermostat, is mounted to the interior surface of tubular body 18 approximately 10 inches to 15 inches from cap 70. Thermostat 106 is operative as a switch for energizing and deenergizing motor 88. Typically, thermostat 106 closes at a temperature rise in the range of 100° F to 140° F, and preferably 120° F, and opens at a temperature drop in the range of 80° F to 120° F and preferably at 100° F. That is, in the preferred embodiment, thermostat 106 closes when the ambient temperature about the thermostat rises to 120° F and opens when the ambient temperature drops to 100° F. 
     As best shown in FIG. 4, power from a source 108 is applied to one side of thermostat 106 via a line 110 and is applied to one side of rheostat 94 via a line 112. The other side of thermostat 106 is connected to one side of motor 88 via a line 114 and the other side of motor 88. Preferably, lines 110, 112 and 114 have an outer covering composed of a high temperature resistance plastic consisting of a tetrafluoroethelyne polymer. A clamp 115 is provided for holding the lines away from blade assembly 90. A sleeve 116, composed of a high temperature resistant material, for example a plastic such as polyvinyl chloride, is placed about lines 110 and 112 as they exit through an opening 118 in tubular body 18. A grommet or strain relief 120, composed for example of rubber or plastic, is inserted into opening 118 to protect lines 110 and 112 against abrasion. The ends of lines 110 and 112 are connected to a male plug 122, which is adapted to be interconnected with source 108, for example a female socket. 
     In operation of heat exchanger 14, male plug 122 is inserted into female socket 108. Then, an open fire is started within opening 12, preferably the flames engulf the medial regions of tubular body 18. When the ambient temperature about thermostat 106 rises to approximately 120° F, the thermostat closes and motor 88 is energized. In consequence, blade assembly 90 rotates and cool air with the room is drawn inwardly through the inlet port. As the cool air passes through tubular body 18, it is heated by the open fire, whereby warm air is exhausted through the outlet port for warming the room. Knob 105 is rotated for controlling the air flow through tubular body 18. If the ambient temperature about thermostat 106 drops to approximately 100° F, the thermostat opens and motor 88 is deenergized. 
     Since certain changes may be made in the foregoing disclosure without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description be construed in an illustrative and not in a limiting sense.