US 3637975 A
An areal heating element, having a polyurethane backing member with an embedding and sealing layer thereon in which is embedded a meandering heating conductor.
Description (OCR text may contain errors)
United States Patent Eilhardt et al. [451 Jan. 25, 1972 AREAL HEATING ELEMENT  References Cited  Inventors: Bernd Eilhardt, Brandriede; Gerhard UNITED STATES PATENTS manmvenbmh Germany 2,138,217 li/l938 Sutter ..219/544 x  Assignee: Kabel-und Metallwerke Gutehoff- 3,020,379 2/1962 Ludlow et al.
nungshutte Aktiengesellschaft, Hannover, 3,043,943 7/1962 Moot ..2l9/449 Germany Primary Examiner-C. L. Albritton  Ffled' 1970 Att0rne'y-Smyth, Roston & Pavitt [211 App]. No.: 15,812
'  ABSTRACT  Foreign Application Priority Data An areal heating element, having a polyurethane backing member with an embedding and sealing layer thereon in which Mar. 14, [969 Germany 10 is embedded a meandering heating conductor.
 US. Cl ..2l9/2l3, 219/345 2 Claims, 2 Drawing Figures  Int.Cl. ..H05b 1/00  Field ofSearch ..2l9/2l3, 345,528, 544,546, 219/548, 538, 449, 450
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xfraz/yizf AREAL HEATING ELEMENT The present invention relates to an areal heating element for direct heating or for indirect heating with temporary buffer storage of thermal energy and using a meandering heating conductor.
' It is known to provide electrical heating conductors in pipes or to provide mats and to install such conductors in floors, walls or ceilings of rooms or to provide heating for streets, airport runways etc. The providing and installation of these types of heating equipment is time consuming and complicated. Thus, it is been suggested to provide and to prepare areal heating elements such as mats in which a heating conductor is run in a meandering contour path. Other heating mats are known using conductors with a layer of low conductivity material in between.
The present invention relates particularly to improvements in heating mats. In accordance with the invention, the heating conductor is provided as a meandering element for a mat which is embedded in a layer of material such as is used or floor covering, e.g., flooring plaster, or in a layer of plastic material. The embedded mat is disposed on a heat transfer impeding layer as backing member provided for disposition between the embedded heating conductor and the wall, floor ceiling etc., of the room or area to be heated. Such an areal heating element can easily be installed and operates as a very effective heater.
Preferably, the mat is embedded in the layer at a distance of one-third the thickness thereof from the surface having the backing, i.e., two-thirds down into the layer from the front. The heating elements can be provided for standard heating power, i.e., in units for 0.5, l or 1.5 kilowatts. The backing member is preferably made of polyurethane foam which was found to significantly impede heat transfer from the heating conductor to the wall.
It should be mentioned that it is known per se to provide a heat transfer impeding layer between a floor and a heating conductor of areal heating installations. However, this known equipment required rather cumbersome procedure for installation. First, that layer was deposited on the floor. Next, the heating conductor was placed thereon and finally heat storage material was deposited thereon in liquid fonn. As stated, this kind of equipment could be installed only in or on floors, not on vertically extending walls or the like. The individually and separately prepared heating elements in accordance with the invention are prepared as self-containing units that can be handled individually and can be installed subsequently on any surface regardless of orientation.
While the specification concludes with claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention, it is believed that the invention, the objects and features of the invention and further objects, features and advantages thereof will be better understood from the following description taken in connection with the accompanying drawings in which:
FlG. 1 is a perspective view of a representative heating element in accordance with the invention; and
FIG. 2 is a cross section along lines 2-2 in FIG. 1.
Proceeding now to the detailed description of the drawings, in FIGS. 1 and 2 thereof there is illustrated a heating conductor l, illustrated as a metallic wire or the like. Altemately, the heating conductor may be included in a corrugated, longitudinally seam welded tubing. The heating conductor is provided in a meander pattern and forms a heating mat together with flat tapes 2.
The thus formed mat is embedded in a layer'4 of sealing material such as used for floor cover or of a suitable plastic material. The thus embedded mat is disposed on a layer 3 which serves as backing member and impedes heat transfer. Thus, the backing layer 3 establishes a direction of preferred heat transfer through the oppositely facing, front surface of embedding and sealing layer 4. Layer 3 may consist, for example, of foamed polyurethane. It was found that particularly good heating is obtained if the heating conductor is placed into layer 4 at about two-thirds of its thickness down from the front, i.e., at one-third of the thickness of layer 4 above the interface with backing member 3. Suitable hanger 5 may be embedded in layer 3, for example, for hanging the areal heating element on a wall or the like. However, the areal heating element may also be used as floor heater and can be installed accordingly.
The areal heating element as described is made as follows:
A flat mold is provided, and the material for forming layer 4 is poured into the mold to provide a flat layer therein having about two-thirds thickness of the embedding and sealing layer to be made ultimately. Independently therefrom a mat is made by means of a heating conductor 1 and of suitable pieces of tape 2. That mat is now placed likewise into the mold. Next, the remaining one-third thickness of the layer 4 is provided by pouring about half the amount of material as was used first onto the mat. Of course, care must be taken that the ends of the heating conductor protrude out of the mold, not to be covered, or other connecting means are provided and connected to the heating conductor to protrude from the layering made.
After the layer material 4 has solidified, foamed polyurethane is placed thereon to establish backing member 3. Hangers 5, if needed, are suitably placed to become anchored in the backing member.
The completed areal heating element can be handled easily. It can be stacked and transported and is easily attachable to vertical walls or the like. If the embedding layer 4 is rather thick, it serves as a thermobuffer, storing thermal energy to obtain uniform heating. Generally, the material for layer 4 should be selected to provide a high thermal energy transfer rate, and in cases, it should also have a rather high heat capacity. The backing member provides insulation so that the efficiency of the areal heating element was found to be very high.
The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.
1. Areal heating element for direct or buffered heating of a room or an area and having two flat sides and two opposite ends, comprising a heat transfer impeding backing member made of polyurethane foam;
an embedding and sealing layer of plastic material on the backing member, having a front surface for facing a room or area to be heated;
at least two flat elongated elements arranged parallel to each other and embedded in the layer and extending therein from one end of the layer of plastic material to the other; and
a heating conductor included in a corrugated longitudinally seam welded tubing and provided in a meandering configuration, disposed on and supported by the flat elements and also embedded in said layer, the meandering configuration running along the extension of the elements so that opposite ends of the heating conductor are provided for electrical connection and on opposite ends of the areal heating element.
2. Areal heating element as in claim 1, the layer having particular thickness, the conductor embedded in the layer at a distance from the front surface. about two-thirds of the thickness down into the layer.
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