Patent Publication Number: US-6216957-B1

Title: Heated floor system for a movable structure

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention relates to a hot water floor heating system for use in connection with a movable structure exposed to cold weather. More particularly, the invention is directed to a gravity-operated hot water circulation heating system for use in outdoor storage cabinets, hunting blinds, ice shanties and the like. 
     Hot water heating systems have long been used to heat structures during periods of cold weather. Such systems generally include a heating element, a water reservoir exposed to the heating element, a pump and a piping or conduit system which extends through the structure for circulating hot water from the reservoir through the structure and back to the reservoir. Systems of this type generally include a radiator or the like located within each space of the structure to be heated. All of the components of the system are permanently mounted within the structure and require a significant amount of time and effort to install. 
     In non-permanent or movable structures, it is known to provide a space heater for heating the interior of the structure. This type of heating arrangement is common in movable structures such as hunting blinds or ice fishing shacks. Heaters of this type take up space within the interior of the structure and provide uneven heat, in that the amount of heat provided to areas remote from the heater is less than that provided to areas closer to the heater. Further, this type of heating arrangement provides little heat to the lower area of the interior adjacent the floor, since heat discharged from the heater tends to rise. Structures of the this type are typically used in cold weather, and it is thus common for occupants to experience uncomfortably cold feet. 
     The same general difficulties are encountered in movable structures which are not intended for occupation by humans, such as cabinets which are located at a construction site or on a vehicle for storing supplies which require heat. Depending on the nature of the items contained within the structure, it may not be possible to locate a heater within the interior of the structure. For example, some types of heaters cannot be located within the interior of a structure housing petroleum products, due to the flammability of such products. 
     Further, when a gas-fired heater is used, it is necessary to vent the heater to the outside of the structure in order to prevent buildup of combustion fumes in the interior of the structure. 
     It is an object of the present invention to provide a heating system for a movable structure in which the heating element is located outside the interior of the structure, so as to eliminate the need to vent the heater and to make available the interior space which otherwise would be occupied by the heating element and its associated venting. A further object of the invention is to provide such a system which distributes heat evenly throughout the interior of the structure. Yet another object of the invention is to provide such a system in which heat is supplied to the lower areas of the structure adjacent the floor. A still further object of the invention is to provide such a system which is relatively simple in its components and construction, yet which provides highly satisfactory heat distribution and operation. 
     In accordance the present invention, a structure includes one or more walls and a floor which cooperates to define an interior, and a heating arrangement is associated with the floor. The heating arrangement includes an internal cavity which underlies the floor and which contains a quantity of fluid, and a heater located exteriorly of the structure. A circulating arrangement is interconnected between the internal cavity and the heating arrangement for circulating fluid from the heater to the internal cavity and from the internal cavity to the heater. The circulating arrangement is preferably in the form of a fluid inlet associated with the internal cavity for receiving heated fluid from the heater, and a fluid outlet associated with the internal cavity for supplying return fluid to the heater from the internal cavity. Heated fluid from the inlet circulates through the internal cavity toward the outlet, and heat from the fluid is dissipated through the floor for heating the interior of the structure. The internal cavity may be defined by a substantially flat tank underlying the floor, and the tank may be constructed and configured so as to underlie substantially the entire surface area of the floor. The tank preferably includes an upper wall over which the floor is located, and one or more side walls depending from the upper wall. The fluid inlet and the fluid outlet are preferably interconnected with one of the tank side walls. The tank is preferably oriented at an angle to horizontal such that the fluid inlet is located at an elevation above that of the fluid outlet, to enable fluid to flow by gravity from the inlet to the outlet. The heater is preferably in the form of a gravity-type heater interconnected with the fluid outlet for receiving return fluid therefrom and interconnected with the fluid inlet for supplying heated fluid thereto. A removable and replaceable fuel tank is adapted for interconnection with the heater, and may either be located within the interior of the structure or exteriorly of the structure. An insulating layer preferably underlies the tank for preventing heat from dissipating from the tank other than through the floor. The structure may either be adapted for storage of items or for occupation by humans, such as a hunting blind or an ice fishing shack. 
     In accordance with another aspect of the invention, a heated floor arrangement adapted for use with a structure includes a heater having an inlet port and an outlet port, and a container or tank including a heat-conductive floor having an upper surface spaced from a lower surface. An inlet valve and an outlet valve are connected to the container and communicate with the space between the upper and lower surfaces of the heat-conductive floor. Tubing is interconnected between the outlet valve and the inlet port of the heater and between the inlet valve and the outlet port of the heater, for circulating fluid to the container from the heater and from the container to the heater. The heat-conductive floor defines a point of lowermost elevation located adjacent the outlet valve, and the inlet valve is positioned at an elevation above that of the outlet valve. The heat-conductive floor slants downwardly from the location of the inlet valve toward the location of the outlet valve, for circulating fluid by gravity through the container. The heat-conductive floor preferably slopes downwardly in both a first direction from the inlet valve toward the outlet valve, and in a second direction transverse to the first direction toward the outlet valve, to ensure circulation of fluid to the outlet valve from the inlet valve. 
     Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The drawings illustrate the best mode presently contemplated of carrying out the invention. 
     In the drawings: 
     FIG. 1 is an isometric view of a movable storage container incorporating the heated floor system of the present invention; 
     FIG. 2 is an isometric view of a non-permanent structure, in the form of a hunting blind, incorporating the heated floor system of the present invention; 
     FIG. 3 is an isometric view of a non-permanent structure, in the form of a runnermounted ice fishing shack, incorporating the heated floor system of the present invention; 
     FIG. 4 is a partial section view taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a partial section view taken along line  5 — 5  of FIG. 1; and 
     FIG. 6 is a section view taken along line  6 — 6  of FIG.  4 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS.  1  and  4 - 6  illustrate a first embodiment of the invention, in the form of a cabinet or container  10  which is adapted for use in an outdoor environment. For example, container  10  may be placed at a construction site for housing supplies, such as grease or oil which are to be maintained in a warm environment to provide proper viscosity for use. Alternatively, container  10  may be adapted for mounting onto a vehicle such as a maintenance truck or the like for housing any supplies components desired to be maintained in a warmed environment. 
     Container  10  generally includes a series of vertical side walls  12 , one of which consists of a stationary vertical panel  14  and a hinged door  16  provided with a handle  18 . A floor  20  extends between side walls  12  for enclosing the bottom of container  10 . A removable top or cover  22  having a pair of handles  24  is adapted for removable engagement with the upper ends of side walls  12 . Side walls  12  and floor  20  cooperate to define an interior  26 , and cover  22  may be removed using handles  24  to selectively provide access to interior  26 . Alternatively, interior  26  can be accessed by opening door  16  with cover  22  in place. Preferably, side walls  12  and cover  22  are formed of a thermally insulating material. 
     Referring to FIG. 4, the lower ends of side walls  12  are adapted to engage a supporting surface  28 , and floor  20  is located above supporting surface  28 , such that a volume is defined between floor  20  and supporting surface  28  bounded by the lower ends of side walls  12 . 
     Container  10  includes a heating arrangement for imparting heat to interior  26 , which generally includes a reservoir or tank  30  located below floor  20 , a heater  32  (FIG.  1 ), a supply arrangement  34  interconnected between heater  32  and tank  30  for providing heated water to tank  30 , and a return arrangement  36  interconnected between tank  30  and heater  32  for providing return flow of fluid from tank  30  to heater  32 . 
     Referring to FIGS. 4 and 5, tank  30  is generally flat and planar, and has a shape corresponding to that of floor  20  so as to encompass substantially the entire surface are of floor  20 . Tank  30  includes a top wall  38 , a bottom wall  40  spaced below top wall  38 , and a series of side walls  42  which extend between and interconnect top and bottom walls  38 ,  40 , respectively, to define an internal cavity  44 . Referring to FIG. 6, a baffle  45  is located within internal cavity  44 . Baffle  45  is in the form of a wall extending between tank top and bottom walls  38 ,  40 , respectively. Baffle  45  extends laterally from one of tank side walls  42 , and terminates at a location spaced from the opposite wall  42 , to define a passage  46 . 
     As shown in FIGS. 4 and 5, a layer of insulation  47  is located below bottom wall  40  of tank  30 , encompassing substantially the entire surface area of tank  40  in order to prevent loss of heat through tank bottom wall  40 . Floor  20  and tank  30  are in intimate contact with each other, in that the underside of floor  20  engages the upper surface of tank top wall  38 . 
     Referring to FIG. 1, an inlet nipple  48  and an outlet nipple  50  are mounted to the tank side wall  42  from which baffle  45  extends. Inlet nipple  48  forms a part of supply arrangement  34 , which also includes an inlet valve  52  mounted to inlet nipple  48  and a supply conduit  54  extending between inlet valve  52  and the outlet of heater  32 . Similarly, outlet nipple  50  forms a part of return arrangement  36 , which also includes an outlet valve  56  and a conduit  58  interconnected between outlet valve  56  and the inlet of heater  32 . Inlet nipple  48  and outlet nipple  50  are located on opposite sides of baffle  45 . 
     Tank  30  is oriented at a compound angle relative to horizontal and relative to side walls  12 . The end of tank  30  adjacent inlet nipple  48  is the point of highest elevation of tank  30 , and tank  30  is pitched relative to horizontal so as to slope or slant toward outlet nipple  50  from inlet nipple  48 . In addition, tank  30  is pitched toward outlet nipple  48  in a transverse direction, i.e. tank  30  slopes or slants toward outlet nipple  50  from the side of tank  30  opposite nipples  48  and  50 . In this manner, internal cavity  44  of tank  30  defines a lowermost point  60  adjacent outlet nipple  50 . 
     With reference to FIGS. 4 and 5, a fill/vent tube  62  extends through floor  20  and tank top wall  38 , and defines a lower end which opens into tank internal cavity  44  at lowermost point  60 . Tube  62  defines a vertical section  64  extending upwardly from the lower end within container interior  26 , and a horizontal section  66  which extends through a sleeve  68  mounted to side wall  12 . Tube  62  defines an upper opening located outwardly of sleeve  68  for communicating exteriorly of container  10 . 
     Heater  32  may be a conventional outdoor heater, such as that typically used to heat engine blocks. Heater  32  is portable and is typically fired using fuel supplied from a separate fuel tank, such as a propane tank having a fuel line interconnected with a fuel inlet for heater  32 . 
     In operation, heated fluid flows from the outlet of heater  32  through supply conduit  54  and into the internal cavity  44  of tank  30  through inlet valve  52  and inlet nipple  48 . The heated water flows into tank  30  and through internal cavity  44 , and heat from tank  30  is transmitted through tank top wall  38  and floor  14  into interior  26  of container  10 . In this manner, heat is supplied to the entire volume of container interior  26 , including the lowermost regions adjacent floor  20 . The heated fluid flows from the uppermost point of tank  30  adjacent inlet nipple  48  first into the upper portion of internal cavity  44  above baffle  45 . The heated fluid then flows through passage  46  into the lower portion of internal cavity  44  below baffle  45 , and circulates through tank internal cavity  44  to lowermost point  60  adjacent outlet nipple  50 . By the time the fluid reaches lowermost point  60 , a majority of the heat from the fluid has been dissipated through tank top wall  38  and floor  20  into container interior  26 , and the cooled fluid is then discharged from tank  30  through outlet nipple  50  and outlet valve  56  into return conduit  58  for supply to the inlet of heater  32 . The fluid is then reheated in heater  32  and again supplied through supply conduit  54  to tank  30 . 
     The heating system, consisting of heater  32 , tank  30 , supply arrangement  34  and return arrangement  36 , is a gravity-fed system in which heated water flows by gravity from the outlet of heater  30  toward inlet nipple  50 , and by gravity through tank internal cavity  44  from inlet nipple  48  to lowermost point  60  and outlet nipple  50 . Fluid from outlet nipple  50  flows by gravity through return conduit  58  to the return inlet of heater  32 . 
     Fill/vent tube  62  is employed to supply additional fluid to the system if necessary, and to provide a vent to prevent the buildup of pressure within tank  30 . Valves  52  and  56  are used to disconnect conduits  54  and  58 , respectively, when heater  32  is not needed or requires service or replacement. 
     The heating medium which circulates through tank  30  and heater  32  may be any satisfactory fluid which can be heated, cooled or circulated. Representatively, the medium may be a liquid such as water or a glycol-based antifreeze such as is commonly used in automotive cooling systems, or a combination thereof. 
     FIG. 2 illustrates an alternative embodiment of the present invention, which may be a structure such as a hunting blind  70 , which includes a series of side walls  72  which are generally similar to side walls  12  of container  10 , and one of which is provided with a window or opening  74 . A roof  76  is fixed to the upper ends of side walls  72  for enclosing an interior defined by hunting blind  70 , which is again generally similar to interior  26  defined by container  10 . 
     Hunting blind  70  includes a floor constructed similarly to floor  20  of container  10 , and a tank  30  and insulation layer  46  underlying the floor. A series of legs  77  extend downwardly from the corners of tank  30  for spacing the tank  30  and the floor of hunting blind  70  above the ground or other supporting surface. Supply arrangement  32  and return arrangement  34  are interconnected with the tank of hunting blind  70  and with heater  32 . FIG. 2 illustrates a fuel tank  78  interconnected with heater  32  through a fuel supply line  80 , for supplying fuel to heater  32 . An awning  82  is mounted to the side wall  72  of hunting blind  70  over inlet and outlet valves  52 ,  56 , respectively, to protect the valves during transport and from weather. 
     While fuel tank  78  and fuel supply line  80  are illustrated in FIG. 2, it is understood that a fuel tank and fuel supply line are also provided for the embodiment of FIG. 1, for supplying fuel to heater  32 . 
     With the arrangement of FIG. 2, heat is supplied to the interior of blind  70  in the same manner as described above with respect to container  10 . 
     FIG. 3 illustrates yet another embodiment of the invention, in the form of an ice fishing shack or shanty  82 . Shanty  82  is mounted on a set of skis or runners  84  mounted to the lower ends of a set of legs  86 , to facilitate movement of shanty  84  over the ground and over ice to a desired location. Shanty  82  includes a series of side walls  88 , one of which includes a transparent window  90 . A roof  92  is located at the upper ends of side walls  86  for enclosing the interior of shanty  82 , which includes a floor similar to floor  20  of container  10 . A tank underlies the floor of shanty  82  in the same manner as tank  30  of container  10 . In this embodiment, fuel tank  78  may be supported on a shelf  94  located within the interior of shanty  82 , with fuel supply line  80  extending outwardly from shanty  82  through an opening formed in one of the side walls  88  for connection to heater  32 . Again, heater  32  functions in the same manner as described previously with respect to container  10  for heating the interior of shanty  82 . 
     It can thus be appreciated that the invention provides a simple and efficient means for imparting heat to the interior of a container or other structure, in which heat is supplied even to the lowermost regions of the structure and evenly throughout the entire volume of the structure. The heating system is simple in its components, construction and operation, and provides a simple and safe means for heating supplies or occupants of a structure without the need to vent exhaust fumes from the interior of the structure and without a heating element being located within the interior of the structure. 
     Various alternatives and embodiments are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter regarded as the invention.