UNDERFLOOR COVERING HEATING SYSTEM

Abstract: An under floorcovering heating pad comprises a heat conducting substrate (22), and a solid conductor resistance heating wire (26) positioned within the substrate (22) in a serpentine manner for heating the substrate. The wire (26) is covered by at least one layer of (28, 30) of material providing electrical insulation and strong mechanical strength, jacketed by an electrically conductive "self-healing" ("self-curing") strong layer (32) of material for the purposes of grounding and protecting the pad. An electrical connector (40) for connecting the resistance wire (26) to a source of electricity includes an earth terminal (42) connected to the jacketed conductive material (32) for grounding the system. The jacketed material is preferably a braid (34) of metal such as stainless steel.

Description: This invention relates to under floorcovering heating systems or pads and the like and in some applications, to systems and pads for the heating of carpets, broadloom, tiles and linoleum. Systems, pads and nets (resistance wire woven into a piece of material embodied in epoxy) have been proposed for positioning under carpets, broadloom, linoleum, tiles and the like for heating the covered floor area. When used with carpet and broadloom, the systems are positioned on the underlay or underpadding. When used with linoleum or tiles, the systems are applied directly onto the substrate or subfloor. These systems and pads suffer many deficiencies. For example, the prior art systems are expensive to install, difficult to maintain and/or have many safety problems. It is therefore an object of this invention to provide an improved under floorcovering heating system and pads and components therefor which are easily installed and serviced and of improved safety. Further, and other objects of the invention will be realized by those skilled in the art from the following summary of the invention and detailed description of an embodiment thereof. In the DE-A-2 157 356 there is disclosed an electric heating blanket which is not installed permanently under a floor. According to the invention these objects are obtained with the features of the under floorcovering heating system or pad of claim 1. Further advantageous embodiments are disclosed in the dependent claims. In one embodiment the solid conductor resistance heating wire is covered by two non-homogeneous (distinct) insulation layers of for example Tefzel (t.m.) or Teflon (t.m.) by Dupont. The insulation material provides high electrical insulation values while at the same time providing a strong mechanical or physical barrier. The material also preferably provides a good humidity barrier. The solid conductor resistance heating wire provides preferably a fixed voltage per square metre. Therefore the resistance of the wire used is varied according to the size of system or pad. To achieve the variable resistance, different alloys may be used, for example an alloy of copper, tin, lead and platinum. The jacketed "self-healing" layer of conductive material for example comprises braided stainless steel. If a sharp foreign object (e.g. pin or nail) engages the layer of "self-healing" material (for example the braid), the material (e.g. braid) resists penetration. If the material is penetrated by the object and then removed, the material (e.g. braid strands) "self-heals" and covers up the opening created by the penetration of the foreign object (for example the strands of braid move to fill the gap, moving towards their original position). The heat conducting substrate is for example a bicomponent polymer [e.g. nylon and P.V.C. (Polyvinyl Chloride) manufactured by BASF which can be rolled up for shipping and unrolled and positioned at the point of installation]. A thermostat may be connected to the system or pad to control the temperature, however not being part of the invention, is not further described. The invention will now be illustrated with respect to the following drawings illustrating embodiments of the invention in which: Figure 1 is a cross-sectional view of a carpet installed on a wooden floor having an under floorcovering heating system disposed on the underlay or underpad according to one embodiment of the invention. Figure 2 is a top plan view illustrating in plan some of the member shown in Figure 1. Figure 3 is a close-up perspective view of resistance wire used in the embodiment shown in Figures 1 and 2. Figures 4 and 5 are close-up views illustrating the "self-healing" ("self-curing") abilities of the jacket covering of the resistance wire to the penetration by a foreign object. Figure 6 is a close-up view of the connector shown in Figure 2 according to an embodiment of the invention. Figure 7 is a side view of the connector shown in Figure 6 to which the resistance heating wire and jacketed material are connected. With reference to Figure 1, there is shown carpet 10 supported on wooden floor 12 supported by wood beams 14. Underpad or underlay 16 is interposed between the floor 12 and carpet 10 and carries on its upper surface 18, under floorcovering heating system 20 comprising (a) heat conducting substrate 22 being a bicomponent polymer of nylon and P.V.C. manufactured by BASF which can be rolled up for shipping and unrolled and positioned at the point of installation. (b) solid conductor resistance heating wire 26 (an alloy of copper, tin, lead and platinum) positioned within the substrate 22 in a serpentine manner for heating the substrate 22, resistance heating wire 26 being covered by two non-homogeneous distinct layers of Tefzel (t.m.) (manufactured by Dupont) 28 and 30 (see Figure 3) to provide electrical insulation and strong mechanical strength and surrounded by jacket 32 of braided stainless steel 34 (manufactured by Harbour Industries, Normandie Avenue, Fanham Quebec) for the purposes of grounding the system and protecting the system. With reference to Figures 4 and 5, two braid strands 32A and 32B of jacket 32 are shown. When a foreign object 36 (as for example a pin 36) penetrates the space between adjacent braids 32A and 32B, the braids are displaced (see Figure 4). When however the object is removed, the braids "self-heal" moving towards their original position covering the opening. With reference to Figure 2, 6 and 7, flat copper connector 40 is provided to which the ends 26A and 26B of the resistance wire 26 are electrically connected. With reference to figure 6, jacket 32 has been removed from each end of the cable and is fastened to ground 42 in the connector 40. Wire ends 26A and 26B are connected to the different terminals - wire end 26A to negative terminal 44 and wire end 26B to positive terminal 46. Connector 40 comprises a pair of holes 40A through the negative terminal, a pair of holes 40B through the positive terminal and a pair of holes 40c through the ground 42. With reference to Figures 6 and 7, ends 26A and 26B have been threaded through holes 40A and 40B respectively (over and under) and the material of the resistance wire 26 proximate the holes is soldered or welded to the connector 40 with the soldering or welding material filling the holes as at 49. Similarly, the jacketed stainless steel braided material 34 removed from each of the wires 26 is gathered as at 50 threaded through the holes 40c (over and under) and soldered as at 49. A thermostat (not shown) may be provided on a wall (not shown). The solid conductor resistance heating wire preferably provides a fixed voltage per square metre. Therefore the resistance of the wire used is varied according to the size of the system or pad. To achieve the variable resistance, different alloys may be used to comprise the solid conductor material (for example an alloy of copper, tin, lead and platinum).

Claims: An under floorcovering heating system or pad for positioning below a floorcovering, comprising (a) a heat conducting substrate (b) solid conductor resistance heating wire positioned within the substrate in a serpentine manner for heating the substrate, the wire covered by at least one layer of material providing electrical insulation and strong mechanical strength, to withstand the loading placed on the floorcovering and prevent damage to the heating wire and jacketed by an electrically conductive "self-healing" ("self-curing") strong layer of material which minimizes the effect of puncturing or other damage on the jacket or hearing wire, the jacket being provided for the purposes of grounding and protecting the system or pad; and (c) electrical connecting means for connecting the resistance wire to a source of electricity including means connected to the jacketed conductive material for grounding the said system. The under floorcovering system or pad of Claim 1, wherein the "self-healing" strong layer of material comprises a metal braid of material. The under floorcovering system or pad of Claim 2, wherein the metal braid of material is a metal braid of stainless steel material. The under floorcovering system or pad of any one of Claims 1 to 3, wherein the at least one layer of material providing electrical insulation and strong mechanical strength is two distinct layers. The under floorcovering system or pad of Claim 4, wherein the solid conductor resistant heating wire comprises two non-homogeneous (distinctive) insulation layers. The under floorcovering system or pad of any one of Claims 1 to 5, wherein the substrate can be rolled up for shipping and unrolled and positioned at the point of installation. The under floorcovering system or pad of any one of Claims 1 to 6, wherein the resistance wire has two ends and the electrical connecting means for connecting the resistance wire to a source of electricity including means connected to the jacketed conductive material for grounding the said system comprises a connector for connecting the ends of the conductor resistance heating wire to a source of electricity, the connector comprising a body having a positive terminal, a negative terminal and a ground, the positive terminal, negative terminal and ground each carrying holes therethrough to permit the ends of the wires to be threaded through the holes, in the negative and positive terminal and the electrically conductive layer to be threaded through the hold of the ground and to permit material of the wire and the electrically conductive material proximate the holes to be mechanically fixed or fastened to the connector by material (eg. solder or a welding material) filling the holes.

Inventors: WILLNER, JONATHAN
Applicants: NUHEAT INC.
Application year: 1989
Main classification: F24D13
IPC codes: H05B3, F24D13, F28F13