Abstract:
This invention relates to a means for using waste heat to preheat water going to a water heater to reduce the amount of energy needed to raise the temperature of the water to a desired level. The invention, further, is portable so that it can be easily moved to accommodate the location of the waste heat source and water heater.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    There are several devices on the market that draw waste heat from clothes dryers, furnace flues, and other sources to warm the surrounding air. These devices typically involve installing a diverter unit at some point downstream of the heat source and directing the waste heat into a living space, hence reducing the energy that would need to be supplied to heat the air to the same temperature. While these devices work well for heating air adjacent to the source of waste heat, they are not suitable to preheating water going to a water heater because they are fixed and the water heater may not be in close proximity to the source of waste heat. The current invention eliminates this problem by providing a portable heat exchanger that can be readily moved and connected between the source of waste heat and the water heater. 
         [0002]    Several patents have been issued which use waste heat to heat or preheat water, however, these appear to be of the permanent or fixed installation type. These include U.S. Pat. No. 7,360,580, 7,216,696, 6,749,014 and 6,564,755. 
     
    
     
       DETAILED DESCRIPTION OF DRAWINGS 
         [0003]    The above and other objects, advantages and features of the present invention will be more fully understood when considered in conjunction with the attached drawings of which: 
           [0004]      FIG. 1  is a dimetric view of the heat source and plenum assembly of the present invention with one side of the plenum assembly removed showing the elements of the heated air collection and transfer portion of the invention; 
           [0005]      FIG. 2  is a dimetric view of a typical installation of the present invention with the outer shell of the heat transfer cabinet removed showing the elements of the heat transfer system according to the invention; and 
           [0006]      FIG. 3  is a dimetric view of a typical installation of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0007]    The present invention is directed to a method of providing preheated water to a domestic or commercial water heater. The invention makes use of hot waste flue gases by using these waste flue gases to heat the air in a plenum chamber and redirecting the heated air through a heat transfer cabinet to preheat the water prior to its introduction into the water heater. 
         [0008]    With initial reference to  FIG. 1 , the method can be accomplished by inserting a plenum assembly  1  into the flow of hot waste gases in the flue  7  from, but not limited to, a furnace  8 , boiler, wood or pellet stove, clothes dryer, solar device or other source of heated air. As the hot gases move through the plenum flue  4 , the air inside the plenum assembly  1  is heated. The amount of make-up air inside the plenum assembly  1  can be controlled by means of an adjustable shutter device  2 . At a predetermined temperature, a switch  6  is activated and a high temperature blower  3  moves the heated air through duct work  5  to the heat transfer cabinet  9  in  FIG. 2 . 
         [0009]    The heated air from the plenum assembly  1  in  FIG. 1  enters the top of a heat transfer cabinet  9  in  FIG. 3  from the duct work  5  and passes over and around a heat transfer assembly  16  shown in  FIG. 2 . Once the heat has been extracted from this air flow, the cooled air is vented from the heat transfer cabinet  9  thru an exhaust port  21  shown in  FIG. 3 . The heat transfer cabinet  9  is mounted on casters  10  to enable it to be easily moved and positioned relative to the chosen heat source. The heat transfer assembly  16  is made of tubing and other fittings arranged and assembled together in such a way as to provide a continuous path for water from a suitable water source  12  such as a municipal water supply, well, spring or other viable source. The tubing and fittings used in the heat transfer assembly  16  are made of copper, type L copper, aluminum or other suitable heat conductive material. The diameter of the tubing used and the effective length of its assembly can be varied to accommodate different heat sources and permit the water moving through the tubing to remain long enough to increase in temperature by at least 10° F. In one part configuration ½ inch tubing was used in an arrangement that provided approximately 196 feet of continuous pathway for the water and proved to be effective in increasing the water temperature by the desired amount. Included in the heat transfer assembly  16  are water hammer arrestors  15  to prevent pressure pounding in the system. As the heated air introduced from the plenum assembly  1  is forced over, around and through the tubing of the heat transfer assembly  16 , heat is transferred through the tubing to the water moving inside. The pre-warmed water then exits the heat transfer cabinet  9  through approved tubing or hose  13  which is fitted with an approved quick detachable fitting or approved union  11  or other approved fittings and enters the hot water heater  14  where the heating is completed with a reduced consumption of energy. Hot water exits the water heater  14  through household plumbing  17  on demand. 
         [0010]    The heat transfer cabinet  9  is made of a framework of wood or other suitable material. The outer covering of the heat transfer cabinet  9  is an insulated shell of exterior grade plywood, metal, molded plastic, fiberglass or other suitable material. The insulation is of sufficient thickness and composition such that heat loss is kept to a minimum. The dimensions of the heat transfer cabinet  9  can be customized so that the insulation is kept from contacting the heat transfer assembly  16  allowing the heated air to circulate freely over and around the tubing of the heat transfer assembly  16 . The heat transfer assembly  16  is attached to cross members  19  of suitable material by means of standard tubing brackets  18  and is supported inside the heat transfer cabinet  9  on supports  20  of wood or other suitable material, thereby making it easily removable for inspection or repair.