Abstract:
A boiler apparatus is provided with a forwardly-opening hinged door. To open the door, the top of the door is moved away from the housing and toward the technician. One or more hinges may be located at the bottom of the door. Since the door does not open sideways, the apparatus requires reduced side-to-side floor space. The door may be used to obtain access to heat transfer surfaces. The door is preferably constructed to minimize the floor space occupied by and required to service the apparatus. The apparatus may include a stand for supporting the boiler at an elevated location for inspection and maintenance. A water tank may be located underneath the boiler.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a boiler apparatus or other fluid heating apparatus, and to a housing for containing and supporting a boiler. The present invention also relates to a door for providing access to a boiler located in a confined location. The present invention also relates to a method of operating and/or maintaining a boiler apparatus. 
     2. Description of the Related Art 
     Known boilers (fluid heating devices) use various combustion processes which produce flue products consisting of water vapor, carbon dioxide, unburned fuel, oxidized contaminants, carbon and other particulate material which may and do adhere to the heat transfer surfaces. These surfaces are designed to absorb the heat of combustion as much as possible before the heat exits the boiler into the vent system. 
     Periodic inspection and cleaning of boiler heat exchange surfaces may be required to insure optimum heat transfer performance. Such maintenance may also be needed to insure that flow passages are free and open so as not to restrict the flow of combustion products. Such obstructions could create back pressure at the burner and reduce proper fuel balance resulting in subsequently less clean burning and increased surface contamination and restriction. There is thus a need in the art for a boiler apparatus that provides optimum heat transfer surface contact for efficient transfer as well as access to the heat transfer surfaces to permit inspection and complete and thorough cleaning when required. 
     A known boiler that provides efficient heat transfer is described in U.S. Pat. No. 4,261,299. The known boiler has an insulated back cover. The cover may be removed to provide access to the interior heat exchange surfaces for maintenance and repair. Obtaining access to the back cover, which is opposite to the front of the boiler (and opposite the burner and controls), requires a clearance space of at least twelve inches (and preferably twenty-four to thirty inches for easier servicing). The known apparatus has significant space requirements. 
     Other known boilers, which vary significantly in design of combustion, heat transfer and flue passages, have removable cleanout panels on the top, sides, back or front. Recently, it has been proposed to mount the burner on a hinged door which could swing to either the right or the left (horizontally) to allow access to passages without physical removal and setting the cover aside. A disadvantage associated with the proposed arrangement, however, is that when the door swings to the side, the burner and the cover require a relatively large side access area. The need for side access space may preclude use of the door. In certain confined locations, the door may have to be removed from the housing to gain access to the boiler for inspection and cleaning. 
     Conventional boilers, due to their heavy weight, are normally mounted on or near the floor. This is a disadvantage because it makes it difficult to service them. The repair technician must be seated on the floor or bent over in an awkward position with poor or incomplete visibility of the passages that need to be inspected or cleaned. 
     Prior art heating devices are shown in U.S. Pat. Nos. 787,617 (Evans); 1,416,487 (Mauck); 2,200,304 (Sands); 2,237,054 (Jensen); 2,562,023 (Dufault); 3,151,615 (Siniaho); 3,934,554 (Carlson); 4,418,649 (Purvis); and 4,872,443 (Ruark). 
     SUMMARY OF THE INVENTION 
     The present invention overcomes many of the problems and disadvantages of the prior art. The present invention relates to an apparatus that has a heater (such as a boiler) for heating water and a housing for containing the heater. According to one aspect of the invention, the heater has a front cover and interior heat transfer surfaces. The housing may have a door for providing access to the heat transfer surfaces. In a preferred embodiment of the invention, the front cover of the heater is a door. One or more hinges may be located at the bottom of the door for supporting the door in a substantially horizontal, open position. 
     According to another aspect of the invention, the heater is a boiler with spiral flow passages, and the passages are covered and sealed by the front cover when the door is in its closed position. In a preferred embodiment of the invention, the inside of the cover may be lined with compressible insulation material. 
     In a preferred embodiment of the invention, the housing is supported on a rigid stand. The stand mays be used to provide space for a water tank without increasing the overall footprint of the apparatus. The stand may also be used to elevate the boiler to a position where it can be easily inspected and serviced by a technician in a comfortable position. 
     According to yet another aspect of the invention, the boiler support legs form a stop or the stand may be used as the hinge stop for supporting the door in its open, horizontal position. If desired, rubber bumpers may be provided on the stand to resiliently support the lightweight door in its open position. 
     According to yet another aspect of the invention, an electrical switch may be activated by the door for automatically disabling the burner when the door is opened. 
     The present invention also relates to a method of operating and maintaining a boiler apparatus. 
     An object of the invention is to provide a boiler apparatus that has reduced space requirements. Another object of the invention is to provide an apparatus that enables easy access and visibility to all combustion areas and passages. 
     According to another aspect of the invention, the boiler may be located on an elevated stand with all water connections and piping on the top or back of the boiler. Once installed, the pipe connections at the back may not need to be serviced. In a preferred embodiment of the invention, all serviceable components are accessible from the front of the apparatus. 
     An advantage of locating the burner in an elevated position is that the passages to be inspected and cleaned are fully visible from a normal standing position. Another advantage of locating the burner in an elevated position is that the stand can accommodate a domestic hot water tank. This way, the boiler and the hot water tank can be located in the same small footprint. 
     In an alternative embodiment of the invention, when vertical height is limited, a base of lesser height may be employed. The reduced height base may perform all of the functions of the taller stand discussed above, except that the reduced height base does not provide a location for the hot water tank. 
     According to another aspect of the invention, a door switch may be located in the electrical box adjacent to the top of the closed door. The switch may be used to disconnect the power supply to the burner upon lowering the door. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other advantages and features of the invention will become more apparent from the detailed description of preferred embodiments given below with reference to the accompanying drawings, in which: 
     FIG. 1 is a front view of a boiler apparatus constructed in accordance with a preferred embodiment of the present invention. 
     FIG. 2 is a side view of the boiler apparatus of FIG.  1 . 
     FIG. 3 is a partial perspective view of the boiler apparatus of FIG. 1, showing the front door in an open position 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring now to the drawings, where like reference numerals designate like elements, there is shown in FIG. 1 a boiler apparatus  10  constructed in accordance with a preferred embodiment of the present invention. The apparatus  10  has a boiler housing  12  and a stand  14  for supporting the housing  12 . In a preferred embodiment of the invention, the legs  15  of the housing  12  rest on the stand  14 . The housing  12  may be formed of sheet metal panels or other suitable materials. The stand  14  may be formed of metal legs and struts or other suitable materials. The housing  12  has a front door  16 . Hinges  18 ,  20  are located at the bottom edge  22  of the door  16 , such that the door  16  opens to the front and downwardly. The door  16  also supports a suitable burner apparatus  24  with flexible fuel and electrical connections (not shown). The open position of the door  16  is shown in dotted lines in FIG.  2 . 
     As shown in FIG. 3, an insulated spiral boiler  26  is located within the housing  12 . Fuel and combustion air are supplied to the boiler  26  by the burner through a suitable opening  28 . The boiler  26  has spiral flow passages  30 ,  32  for providing heat transfer in the manner described in U.S. Pat. No. 4,261,299, the entire disclosure of which is incorporated herein by reference. The flow passages may include an inner passage  30  and an outer passage  32 . The combustion chamber  29  for the boiler  26  may be constructed according to U.S. Pat. No. 4,425,875, the entire disclosure of which is incorporated herein by reference. The present invention should not be limited, however, to the specific instrumentalities described and referred to herein. 
     An insulated multi-component cover  34 ,  36  is located within and is supported by the door  16 . The cover may include a board  34  and a liner  36 . The board  34  may be about two inches thick. In the illustrated embodiment, the board  34  fits within the door  16  and has approximately the same height and width as the door  16 . The board  34  may be formed of moderate heat-insulating material. The liner  36  is integrally connected to the board  34 . The liner  36  may be formed of high temperature resistant insulation. When the door  16  is closed (solid lines in FIGS.  1  and  2 ), the cover  34 ,  36  is in a vertical position and seals off the spiral passages  30 ,  32 . The high temperature liner  36  seals the inner passage  30  and the board  34  seals the outer spiral passage  32 . In other words, the cover  34 ,  36  is shaped to fit and provide a seal against both spiral passages  30 ,  32 . When the door  16  is open, the cover  34 ,  36  is located within the door  16  in the horizontal position shown in FIG. 3 (dotted lines in FIG.  2 ). In the horizontal open position, the door  16  may extend no more than about eight inches beyond the floor space required for the apparatus  10  when the door  16  is in the dosed position, although the present invention should not be limited to the specific dimensions shown and referred to herein. In other words, the dimension  104  shown in FIG. 2 (from the burner  24  in the closed position to the top  56  of the door  16  in the open position) may be less than or equal to eight inches. 
     An insulated water supply tank  40  may be located within the stand  14  and beneath the boiler housing  12 . Since the stand  14  has an open construction, it is relatively easy to install the tank  40  beneath the housing  12 . In addition, the tank  40  is not hidden from view. The tank  40  may be used to store domestic hot water heated by the boiler  26 . The tank  40  may be connected to the boiler  26  by suitable conduits (not shown). As shown in FIG. 2, room is provided for the burner  24  to be located in front of the tank  40  in the door-open position. Additional conduits and valves  42  may be provided for supplying fuel to the burner  24  and the boiler  26  and for providing water to be heated. The conduits and valves  42  are preferably located toward the rear of the apparatus  10  so that they do not interfere with movement of the door  16  or obstruct access to the boiler passages  30 ,  32  when the door  16  is open. 
     The boiler apparatus  10  preferably occupies a minimum amount of floor space so as to fit easily within a closet or other confined location of a residence or commercial building. In a preferred embodiment of the invention, the floor space occupied by the apparatus  10  does not substantially exceed the space occupied by the water supply tank  40 . The apparatus  10  may be configured so that all of its components are accommodated substantially within the width of the insulated boiler  26 , i.e., such that the total installed width of the apparatus  10  is no more than about one inch (on each side) greater than that of the width of the boiler insulation  44  and side jackets  46 . In other words, the width  100  (FIG. 1) of the stand  14  may be no more than about two inches greater than the width  102  of the housing  12 . If desired, the slightly greater width of the stand  14  may be used to cause the housing side panels  46  to be slightly spaced away from combustible material (such as a combustible wall, not illustrated). 
     The spiral boiler  26  by design has relatively cool outer surfaces. Additional insulation  44  (FIG. 3) is wrapped around the outside of the boiler  26  to further contain heat so that the side jacket surfaces  46  remain cool. The wrapped insulation  44  may be formed of glass wool or another suitable material. The reduced temperatures permit the sides  46  of the housing  12  to be located close to combustible materials (e.g., within one inch of combustible materials), which reduces the amount of space occupied by the boiler apparatus  10 . 
     In operation, to service the apparatus  10 , bolts  50 ,  52 ,  54  (or other suitable connectors) may be released to disconnect the top  56  of the door  16  from the housing  12 . The door  16  may then be rotated downwardly about the hinges  18 ,  20  (by moving the top portion  56  away from the housing top panel  58 ). A switch  60  may be provided on the top panel  58  such that opening the door  16  automatically disables operation of the boiler  26  or burner  24  mounted on the door  16 . A front lower portion  62  of the door  16  engages a top portion of the stand  14 , such that the door  16  rests in the illustrated horizontal position. The door  16  does not rotate downwardly beyond the illustrated horizontal position. In the open position, the service technician can inspect and service the boiler passages  30 ,  32  and the combustion chamber  29 . 
     During servicing, the door  16  may be located between the technician and the opened boiler  26 . The spiral passages  30 ,  32  stay in the housing  12  and do not move. In its horizontal position, the door  16  may be used to support tools, light sources or other equipment. No additional space on the side of the boiler apparatus  10  is needed to provide access to the boiler  26 . When the servicing is completed, the door  16  is returned to its upright (FIG. 1) vertical position. The bolts  50 - 54  are then secured again to the housing  12 , and the snitch  60  automatically enables operation of the boiler/burner  24 ,  26 . The switch  60  may be activated by the top  56  of the front cover  16 . 
     The hinges  18 ,  20  may have an adjustment means for tightening the lower portion of the cover  16 ,  22 ,  34  to create an effective seal for the boiler  26 . The adjustment means may be, for example, threaded rods  80  for adjusting the positions of the hinges  18 ,  20  relative to the housing  12 . 
     In a preferred embodiment of the invention, the door  16 , the hinges  18 ,  20 , and the stand  14  may have sufficient rigidity such that no additional support for the door  16  is required in the open position (FIG.  3 ). In a preferred embodiment of the invention, the bottom  62  of the door  16  rests on rubber bumpers  64 ,  66  on the upper front face of the stand  14 . 
     If desired, the boiler liner  36  may be formed of a soft, compressible, high temperature insulation material. The insulation material may be integrally built into the door  16 . The insulation material seals off the interior  30  of the boiler  26  from the interior of the housing  12  when the door  16  is closed. The compressible nature of the insulation material accommodates any misalignment of the door  16  with respect to the boiler  26  when the door  16  is in the closed position. 
     While preferred embodiments of the invention have been described and illustrated, it should be apparent that many modifications can be made to the preferred embodiments without departing from the spirit or scope of the present invention Accordingly, the invention is not limited by the foregoing description or drawings, but is only limited by the scope of the appended claims.