Abstract:
There is described a heating panel comprising: a heat conductive plate having a first surface that is grooveless and planar and an opposite surface thereof; a self-regulating heating cable residing on the first surface; and an insulating layer covering the self-regulating cable and the first surface to direct the heat towards the opposite surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is the first application filed for the present invention. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to the field of residential, commercial, and industrial heating systems. 
       BACKGROUND OF THE INVENTION 
       [0003]    Electric ceiling or floor heating systems usually comprise regular series resistive wires in which an electric current flows. The resistance of the wires converts the electric energy into heat. These electric heating systems are particularly efficient as an additional heating source. However, these systems present a fire hazard. As a result, they cannot be installed directly in contact with wood for example. Not leaning the heating system against the wood implies a waste of heat and renders the heating less efficient. Other models allow direct contact with wood, but are limited in the thickness of the wood itself. 
         [0004]    Therefore, there is a need for improving the safety of heating systems of this kind without reducing their efficiency. 
       SUMMARY OF THE INVENTION 
       [0005]    In accordance with a first broad aspect, there is provided a heating panel comprising: a heat conductive plate having a first surface that is grooveless and planar and an opposite surface thereof; a self-regulating heating cable residing on the first surface; and an insulating layer covering the self-regulating cable and the first surface to direct the heat towards the opposite surface. 
         [0006]    In accordance with a second broad aspect, there is provided a heating floor comprising: a floor having a walking side and an underside; and at least one heating panel attached to one of the underside and the walking side of the floor and comprising a heat conductive plate having a first surface that is grooveless and planar and an opposite surface thereof; a self-regulating heating cable residing on the first surface; and an insulating layer covering the self-regulating cable and the first surface to direct the heat towards the opposite surface. 
         [0007]    In accordance with a third broad aspect, there is provided a heating ceiling comprising: a ceiling having a top side and an opposite bottom side; and at least one heating panel attached to one of the top side and the bottom side of the ceiling and comprising a heat conductive plate having a first surface that is grooveless and planar and an opposite surface thereof; a self-regulating heating cable residing on the first surface; and an insulating layer covering the self-regulating cable and the first surface to direct the heat towards the opposite surface. 
         [0008]    In accordance with a fourth broad aspect, there is provided a heating wall comprising: a wall; and at least one heating panel embedded within the wall and comprising a heat conductive plate having a first surface that is grooveless and planar and an opposite surface thereof; a self-regulating heating cable residing on the first surface; and an insulating layer covering the self-regulating cable and the first surface to direct the heat towards the opposite surface. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Further features and advantages of the present invention will become apparent from the following detailed description, taken in combination with the appended drawings, in which: 
           [0010]      FIG. 1  is a top view of a heating panel in accordance with one embodiment; 
           [0011]      FIG. 2  is a cross-sectional view of a heating panel with a flexible insulating material, in accordance with one embodiment; 
           [0012]      FIGS. 3A and 3B  are cross-sectional views of a heating panel with a rigid insulating material, in accordance with two embodiments for the insulating material; 
           [0013]      FIG. 4  is a top view of a heating panel with a u-shaped self-regulating cable having wires extending through a side of the panel, in accordance with one embodiment; 
           [0014]      FIG. 5  is a side view of the heating panel of  FIG. 4 ; 
           [0015]      FIG. 6  is a top view of a heating panel with a u-shaped self-regulating cable having wires extending through a top of the panel, in accordance with one embodiment; 
           [0016]      FIG. 7  is a side view of the panel of  FIG. 6 ; 
           [0017]      FIG. 8  is a schematic illustrating a parallel connection of two heating panels, in accordance with one embodiment; 
           [0018]      FIG. 9  is a side view of a heating ceiling installed on a top floor/roof ceiling, in accordance with one embodiment; 
           [0019]      FIG. 10  is a side view of a heating ceiling installed on an inner ceiling, in accordance with one embodiment; 
           [0020]      FIG. 11  is a side view of heating panels installed underneath a floor, in accordance with one embodiment; 
           [0021]      FIG. 12  is a side view of heating panels installed on top of a floor with a floor cover directly on the heating panels, in accordance with one embodiment; 
           [0022]      FIG. 13  is a side view of heating panels installed on top of a floor with spacing between the panels and the floor cover, in accordance with one embodiment; 
           [0023]      FIG. 14  is a side view of a heating panel installed on a floor that juts out from the rest of the residence; and 
           [0024]      FIG. 15  is a top view of heating panels embedded in side walls, in accordance with one embodiment. 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    The heating system presented herein uses self-regulating electric cables as a heat-source. The self-regulating cable comprises two electric conductive wires arranged in parallel and surrounded by a semi-conductive plastic material which has an electric conductivity that varies with temperature. A semi-conductive plastic material is also provided in between the two conductive wires. The conductivity of the plastic material is inversely proportional to temperature, and the plastic material reduces its conductivity to a negligible current at a predetermined threshold temperature. By applying different electrical potentials to both conductive wires, an electrical current flows through the semi-conductive plastic material located between both conductive wires along the entire length of the self-adjusting cable. The flow of current through the plastic material generates heat. The magnitude of the current varies with the conductivity of the plastic material, which varies with temperature. As a result, in low temperature regions of the self-adjusting cable, both the conductivity of and the current flowing through the plastic material are higher, and this generates heat. In the high temperature regions of the self-adjusting cable, both the conductivity of and the current flowing through the plastic material are lower, and less heat is generated. In regions of the self-adjusting cable where the temperature is higher than the threshold temperature, the current flow drops to a minimum between both conductive wires and minimum heat is generated. 
         [0026]    In addition to regulating the temperature by itself, a self-regulating cable also reduces the fire hazard in comparison to traditional electric cables and wires since the electric current drops to a minimum when the temperature of the self-regulating cable has reached a threshold. 
         [0027]      FIG. 1  illustrates one embodiment of a heating panel  10 . The heating panel  10  comprises a casing  12 , a plurality of self-regulating cables  14  and a thermal insulating layer  16 . The casing  12  accommodates the self-regulating cables  14  and the insulating layer  16 . 
         [0028]    As shown in  FIG. 2 , a self-regulating cable  14  is embedded between the casing  12  and the insulating layer  16 . The self-regulating cable  14  comprises two conductive wires  20  and a plastic material  22  of which the conductivity varies with temperature.  FIGS. 2 and 3  illustrate the cable as having a pseudo-rectangular shape. It should be understood that round cables may also be used, or self-regulating cables of any other shape known to a person skilled in the art. 
         [0029]    The casing  12  comprises a heat conductive plate  24  and two flanges  26 . The heat conductive plate  24  is made of a heat conductive material and presents a planar surface. The self-regulating cable  14  resides on the heat conductive plate  24  so that heat generated by the self-regulating cable  14  is transferred to the heat conductive plate  24 . As the heat conductive plate  24  is made of a heat conductive material, the generated heat propagates along the heat conductive plate  24 . The insulating layer  16  is used to direct the heat in the direction of arrow B. 
         [0030]    The planar shape of the heat conductive plate  24  improves the heat transfer between the self-regulating cable  14  and the heat conductive plate  24  and reduces the amount of heat wasted in the case of a non-planar surface. The heating panel  10  may be provided with a cover on top of the casing  12  to enclose the self-regulating cable  14  and the insulating material  16  inside the casing  12 . 
         [0031]    In one embodiment, the self-regulating cable  14  and the insulating layer  16  are deposited on top of the heat conductive plate  24  and a cover is used to maintain the assembly in position. Alternatively, the self-regulating cable  14  and/or the insulating layer  16  can be secured on the heat conductive plate  24 . Any mechanical connector such as an adhesive, an adhesive tape, or a heat transfer tape can be used. 
         [0032]    In one embodiment, both the heat conductive plate  24  and the flanges  26  are made of a heat conductive material. It should be understood that any material characterized as having good heat conductivity can be used. Examples of materials are aluminium, satinized steel, galvanized steel, regular steel, etc. Alternatively, only the heat conductive plate  24  of the casing  12  is made of a heat conductive material. The heat conductive plate may be rigid or flexible. The thermal insulating layer  16  can be made of any thermal insulating material having any form. For example, it can be in the form of a rigid material such as polystyrene, a foam such as opened-cell or close-cell foams, or a flexible material such as glass wool, rock wool, acoustic lining, etc. 
         [0033]      FIGS. 3A and 3B  illustrate two embodiments of a heating panel  50  comprising a rigid insulating panel  52 . In  FIG. 3A , the insulating panel  52  comprises grooves  54  designed to accommodate the self-regulating cable  14  which is embedded between the insulating panel  52  and a heat conductive plate  56 . In  FIG. 3B , the insulating layer does not have grooves and air is between the insulating panel  52  and the conductive plate  56  where the self-regulating cable  14  is not present. Another insulating material may also be present in this space  53 . 
         [0034]    Alternatively, a heat conductive material, such as concrete, can be present in the space  53 . This conductive material is used to create a heat mass that will redistribute the heat generated by the self-regulating cable  14  across the entire panel. Such a panel can be used in a sidewalk, driveway or other to melt away snow or ice. Using concrete as the additional conductive material makes it solid enough to withstand the weight of vehicles that may be driven over it when covered with concrete, asphalt, stones or other. The concrete (or other conductive material) is poured over the cable and hardens around it, thereby embedding the self-regulating cable  14  within this additional conductive material. The insulating layer  52  is then placed on top of the additional conductive layer. When positioned in the ground for snow melting, the conductive plate  56  faces upwards to direct the heat towards the snow and melt it away. When used in freezers as a frost barrier, underneath a concrete floor, the conductive plate  56  is installed face down on the soil with the insulating material facing up towards the floor. 
         [0035]    The insulating panel  52  illustrated in  FIGS. 3A and 3B  is rigid, which increases the mechanical resistance of the heating panel  50 . The conductive plate  56  can be fixed to the insulating panel  52  by an adhesive or other types of fixing means. In one embodiment, the self-regulating cable  14  and the insulating panel  52  are embedded into a casing such as casing  12  illustrated in  FIG. 2 . A cover may also be provided to maintain the assembly into position. In this case, the insulating panel does not need to be fixed to the casing. 
         [0036]    Since each one of the conductive wires  20  of the self-adjusting cable  14  only needs to be connected to a respective electrical potential at one end of the cable, the self-adjusting cable  14  can be cut anywhere along its length. Any shape can be given to the self-adjusting cable. 
         [0037]      FIG. 4  illustrates one embodiment of a heating panel  60  comprising a U-shaped self-regulating cable  62  embedded in a casing  64 . It should be understood that the U-shape is one of many configurations possible for the self-regulating cable  62  and should not be considered limiting. Other possible configurations are a straight line, circular shapes, closed perimeters, etc. For simplification purposes, the insulating layer is not shown in  FIG. 4 . The self-regulating cable  62  has a U-shape that improves the heat distribution along the heat conductive plate of the casing  64 . An electrical wire protector  66  is positioned on one side of the casing  64  around an aperture on one end thereof. The feeder wires  68  comprise a ground feeder wire and two electrical wires connected to different potentials. The feeder wires  68  enter the aperture and are connected to the conductive wires  70  of the self-regulating cable  62  and to a ground wire  72 . The ground wire  72  is connected to a ground screw  74 , as illustrated in  FIG. 5 , in order to ground the casing  64 . 
         [0038]      FIG. 6  illustrates one embodiment of a heating panel  80  having a junction box  82  located on top of a casing  84 . For simplification purposes, the insulation layer is not shown in  FIG. 6 . The feeder wires  68  enter the junction box  82  and are connected to the conductive wires  86  of a self-regulating cable  88  and to a ground wire, as illustrated in  FIG. 7 . 
         [0039]    Several heating panels can be used to create a heating floor or heating ceiling, for example.  FIG. 8  illustrates one embodiment of the parallel electrical connection of two heating panels  60  to a single feeder cable  90 . The feeder cable  90  is connected to a power supply (not shown) and comprises two conductive feeder wires  92  having a different electrical potential and a ground feeder wire  94 . The feeder cable  90  and the feeder wires  92 ,  94  are provided in the vicinity of the connectors  66  of the heating panels  60 . The conductive wires  70  of the self-adjusting cables are connected to the conductive feeder wires  92  and the ground wire  72  of the heating panels  60  is connected to ground feeder wire  94 . A sleeve can be used to protect the electrical connections. 
         [0040]    The electrical connection principle illustrated in  FIG. 8  can be applied to the heating panels  60  illustrated in  FIGS. 6 and 7  and having the connectors  82  located on top of casing  84 . The feeder cable  90  is connected to a thermostat used to control the temperature of a room heated by the heating panels. The thermostat turns the power on or off according to a preset temperature. 
         [0041]    While the feeder cable  90  and the heating panels  60  and  80  are adapted to ground the heating panels  60  and  80 , it should be noted that the heating panels  60  and  80  do not have to be grounded between the panel and junction box since they are spot welded together. 
         [0042]    In one embodiment, a first group of heating panels can be connected together in series to a first thermostat and a second group of heating panels can be connected in series to a second thermostat. This configuration allows both groups of heating panels to be separately controlled. Alternatively, each heating panel can be controlled by a corresponding thermostat or all heating panels can be controlled by a single thermostat. 
         [0043]    The heating panels can be used as a principal heating system or as an additional heating system. The required number of heating panels depends on their function. Usually, a greater number of heating panels is required to create a principal heating system. The heating capacity of the self-adjusting cables and their length within a heating cable also affect the performance of the heating system. 
         [0044]      FIG. 9  illustrates one embodiment of an outside heating ceiling  100  installed in a roof  102 . The roof  102  comprises a truss  104  on which a thermal insulation layer  106 , such as glass wool, is deposited. The internal face  108  of the truss  104  is covered with a vapour barrier  110 . Heating panels  112  are secured below the vapour barrier  110  between two following furrings  114 . The heating panels  112  can be any one of heating panels  10 ,  50 ,  60  and  80 . The heating panels  112  are installed with their heat conductive plate facing down so that the generated heat goes down in the direction of arrow B. 
         [0045]      FIG. 10  illustrates one embodiment of a heating system  120  installed in an interior ceiling. The heating panels  112  are secured below a joist  122  of an internal ceiling. The heating panels  112  are located between two following furrings  124 . The heating panels  112  are installed with their heat conductive plate facing down so that the generated heat goes down in the direction of arrow C. An insulating layer  128  such as glass wool is also installed on top of the heating panels  112  in order to improve the heating of the room. 
         [0046]    In one embodiment, the width of the heating panels  112  is substantially equal to that of furrings  114 ,  124  in order to facilitate the installation of a board such as a gypsum board below the furrings  114 ,  124  and the heating panels  112 . It also improves the contact and the heat transfer between the gypsum board and the heating panel. While the present application refers to gypsum boards, it should be understood that any other boards such as chipboards can be used. 
         [0047]      FIG. 11  illustrates one embodiment of heating system  130  installed below a floor  132 . Heating panels  134  are secured below the floor  132  between two following joists  136 . The floor  132  may be covered with ceramic tiles  138 , for example. The floor can be made of any type of material, including wood and concrete, as is found in large commercial buildings having a garage underneath a first floor of offices. 
         [0048]    Alternatively, the heating panels  134  may be embedded between the floor  132  and the ceramic tiles  138  as illustrated in  FIG. 12 . The heating panels  134  can be any ones of heating panels  10 ,  50 ,  60  and  80 . The heating panels  134  are installed with the insulating layer facing down in order to direct the generated heat in the direction of arrow D. While  FIGS. 11 and 12  refer to ceramic tiles  138  as a floor covering, it should be noted that other floor coverings such as a linoleum or a carpet can cover the floor  132 . Alternatively, no floor covering can be present on top of the floor  132 . 
         [0049]    In the case of the heating system  140  illustrated in  FIG. 12 , the heating panels  134  are preferably of the kind of heating panels  50  illustrated in  FIG. 3 . The heating panels  134  are installed on top of the floor  132  below the ceramic tiles  138  with their insulating layer facing down. Having a rigid insulating layer increases the mechanical resistance of the heating panel so that a person can walk on the ceramic tiles without any risk of damaging the heating panels. It should be understood that the heating panels may be installed on top of any type of floor, such as wood or concrete floors. 
         [0050]      FIG. 13  illustrates an embodiment similar to that shown in  FIG. 12 , but where a material, such as wood panels or concrete plates are provided between the heating panels  134  and the floor covering  138 . A series of posts  137  are used to raise the floor covering  138  and provide the space. 
         [0051]      FIG. 14  illustrates another type of environment in which a heating panel can be used to heat a floor. In this case, the panel  134  is used to heat a floor of a room  135  which extends beyond the walls of whatever space is found below it. Directly beneath the room  135  is the outside air  137 , which would result in a colder floor if the heating panel were not used. The heating panel  134  may be placed on top of the floor, as illustrated in  FIG. 12 , or beneath the floor, as illustrated in  FIG. 11 . 
         [0052]      FIG. 15  illustrates one embodiment of a wall heating system  200  which comprises heating panels  202 ,  204  installed inside walls. The heating panel  202  is used to warm up towels laying on a towel rack  106  and the heating panels  204  are used to heat-up the walls of a shower unit  208 . The heating panels  202  and  204  are installed inside walls behind a gypsum board  210 . The heat conductive plate of the heating panels  202 ,  204  is facing the gypsum board  210  in order to direct the generated heat towards the towel rack  206  and the shower unit  208 , respectively. 
         [0053]    Heating panels can be installed in other locations such as in the frame of a window for example. A single heating panel may be installed either in a ceiling or in a floor at a specific location, such as where a chair happens to be, for example. 
         [0054]    Having the electric heating cables be self-regulating allows an easy installation. The self-regulating cable may be in contact with wood without risking a fire hazard. Conventional electric cables would fail to satisfy the fire-safety regulations if installed directly underneath the floor. 
         [0055]    The heating panels can be secured to the floor, the ceiling or the wall with screws, adhesive, and/or special clips supplied therefor. Any mechanical connector can be used. The heating panels can be of any shape and size. They can be rectangular, square or circular. They can also be designed to fit one into the other to form a continuous floor or ceiling for example. In addition, a same self-regulating cable may be used by a plurality of panels, or each panel may have its own self-regulating cable. 
         [0056]    It should be noted that the embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.