US 3550267 A
Description (OCR text may contain errors)
H. H. WILLIAMS METHOD OF FABRICATING A HEATING ELEM Dec. 29, 1970 ENT Filed Oct. 9, 1967 lllm" INVENTOR HARRY H. WILLIAMS United States Patent O 3,550,267 METHOD OF FABRICATING A HEATING ELEMENT Harry H. Williams, 400 E. Adams St., Muncie, Ind. 47905 Filed Oct. 9, 1967, Ser. No. 673,588 Int. Cl. Hb 3/28 U.S. Cl. 29-611 6 Claims ABSTRACT OF THE DISCLOSURE A method of fabricating a heating element having a base-sheet of fire resistant material, and an electrical cable assembly formed by a doubled over length of heating wire having a loop end and two halves extending therefrom to two free ends connected to non-heating electrical lead conductors.
BACKGROUND OF THE INVENTION It has heretofore been proposed to pre-assernble for installation in buildings a radiant heating panel formed of gypsum board or the like having substantially plane front and rear faces and provided in its rear face with a repeatedly retroverted groove containing a length of resistance wire. In one form of such a panel, shown in Patent 3,095,491, to G. P. Deacon, the ends of the resist ance wire are connected, at the time of installation, to the non-heating conductors of a two-wire cable at points within the groove, while in another, shown by my prior Patent 3,277,273, the ends of the resistance wire are connected at the time of installation to appropriate nonheating leads at points outside the panel. In the conventional manner of making such panels, the groove and Wire must be of matching lengths, and the resistance wire is laid in the panel groove by starting with one end of the wire at one end of the groove working progressively along the length of the groove and wire until the other end is reached. Thereafter, the connections to the leads are made.
Soldered connections between the resistance wire and its leads are not permitted, and it is common practice to insert the end of the resistance wire and an end of its lead into opposite ends of a tubular metal connector which is then crimped or staked to effect the electrical connection. A sleeve of insulating material is placed over the connector. A connection of this general type is shown in the aforesaid Deacon patent. Building codes generally require that connections so effected carry the approval of Underwriters Laboratories, Inc., hence they must be made in a factory where they can be inspected by an Underwriters inspector, and cannot be made at the installation site. As a result, the heating panels, with the resistance wire in place and with the leads connected are commonly preassebled into units, and such units shipped as such to the site of installation.
Transportation costs place a practical limit on the distance between the place where such units are manufactured and the place where they are to be installed. The problem thus presented cannot be readily solved by multiplying manufacturing sites, as it is impractical to establish the conditions to secure Underwriters approval at a multiplicity of small factories scattered throughout the country. My present invention makes it possible to assemble radiant heating panels at scattered convenient locations without incurring excessive transportation costs, while fully satisfying requirements for Underwriters approval.
SUMMARY OF THE INVENTION In accordance with the invention, an electrical resistance wire is cut to predetermined length to give the deice sired resistance heating characteristics, and its ends are connected by crimped connectors or by other means meeting Underwriters requirements, to appropriate leads which are preferably the two conductors of a two-wire, flexible cable of approved type. Conveniently, the resist ance wire is doubled over at its mid-point and its two ends brought into juxtaposition before the connections to the leads are made. The assembly of the doubled-over resistance wire and connected lead cable is then wound as a continuous unit into a coil, preferably on a spool or reel, with the cable arranged to be unwound first. Coils thus prepared are suitable to receive Underwriters approval as such, and may be distributed to manufacturing plants for assembly into complete panels without need for fur ther Underwriters approval to satisfy building codes. When the wire assembly is installed in a grooved panel, the wire-receiving grooves in the panel are formed in a serpentine pattern, and preferably in a pattern of parallel grooves wherein each point along the groove for one half of the heating wire, as measured from the lead end, is disposed in parallel with the corresponding point of the groove for the other half. The wire assembly is installed in the groove by starting with the lead end and working progressively toward the doubled bight in the wire. A cross-connection groove is cut between the parallel grooves to receive the bight, as the installation is completed.
BRIEF DESCRIPTION OF THE DRAWING The accompanying drawing illustrates the invention. In such drawing:
FIG. 1 is a plan view of the rear face of a heating panel in which is installed a heating cable assembly in accordance with my invention;
FIG. 2 is a perspective view of a lead-retaining cl1p shown in FIG. 1; and
FIG. 3 is a perspective view of my heating cable assembly partially wound on a spool in accordance with my invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT In the construction shown in FIG. 1, a doubled over length of electrical heating wire 10 has its free ends 12 brought into juxtaposition and connected to the two wires 18 of a cable 14, and such assembly is installed in a heating panel 16. The two wires 18 of the cable 14 are each enclosed in insulation and are held together by an additional insulating sheath 20. The heating wire is connected to the lead conductors by insulated clips 26. The panel 16 comprises a rectangular sheet of gypsum board, plaster board, or like fire resistant material, the rear face 22 of which is provided with a continuous serpentine groove 24 for the reception of the heating wire 10 and of short lengths of the lead conductors and the connectors 26 which join the ends of the heating wire to the conductors 18. Preferably a backing sheet 28 of paper or metal foil is applied to the rear face of the panel after the heating wire has been installed. The connectors 26 are conveniently disposed near an edge of the panel and the two-wire cable 14 emerges at the middle of one edge of the panel. At such emergence, the panel may be reinforced with a clip 30, shown in perspective in FIG. 2. The clip 30 is formed of a rigid material and has a body portion 32 and a pair of spaced apart fingers 34 extending from one end thereof which are bent to embrace the edge of the panel to help hold the clip in place. The clip portion is fixed to the panel as by an adhesive or by a tack passed through a hole 36 in the clip and into the panel. The cable emerges from the panel between the fingers of the clip which adds support to the edge of the board and prevents damage thereto.
The serpentine groove 24 in which the heating wire lies is preferably formed, as shown, in a pattern of a pair of spaced parallel channels, where any point, as measured from one end of the groove, is adjacent but spaced apart from a point along the groove as measured from the other end. Both halves of the heating wire 10 are inserted at the same time in the parallel grooves 24 starting with the lead conductors 18 and working progressively toward the doubled bight 38. It is a simple matter to cut a cross connection 39 between the parallel grooves at a point to receive the bight 38 of the heating wire as the wire insertion is completed. Such cross-connection 39 can be cut at any point, such as at 39' shown in dotted lines, to suit the position of the bight 38 when the rest of the wire has been installed.
For shipment and to facilitate installation, the preassembly of doubled-over wire 10 and the connected leads 18 of the cable 14 is wound in a package or on a spool in the arrangement shown in FIG. 3. As shown, the assembly is partially wound onto a spool 40, with the midpoint or bight 38 of the doubled-over heating wire wound first on the spool 40 so that it will be the last portion of the assembly to be unwound, and with the lead end or cable 14 of the assembly wound last on the spool so that it will be the first portion to be unwound.
Installation of the heating wire assembly is conveniently accomplished by pressing the connectors into the groove 24 adjacent the edge of the panel and adjacent the clip 30. Both halves of the heating wire are then pressed into the groove concurrently, either by machine or manually while the wire is drawn progressively from the spool or coil. When the mid-point 38 of the wire is reached an additional groove may be cut, as needed, to allow the wire to be pressed into the panel.
The wire assembly may also be installed in other ways than by insertion in a pre-cut groove; for example, it may be stapled to a wall or ceiling surface. The preassembled heating unit in accordance with the invention will provide corresponding advantages in any such other method of installation, in that the installation will start with the lead end of the assembly, and progress lengthwise along both halves of the doubled over wire simultaneously. The location of the bight will be variable to suit the convenience of the installation.
There will be no need to plan ahead to bring the end of the wire to any particular location, as is the case when the installer works progressively from one end of a wire to the other. The doubled wire can be unwound from the package as the installation proceeds, and it will not be be necessary to unwind the entire wire first in order to locate the remote end.
1. A method of fabricating a heating element having a base-sheet of fire resistant material, and a heating cable assembly formed by a doubled over length of heating wire having a loop end and two halves extending therefrom to two free ends connected to non-heating electrical lead conductors, comprising locating the two lead conductors at a desired terminal point on the sheet and, starting at their points of connection to said conductors, securing both halves of the heating wire in laterally spaced relation to the sheet progressively from their lead connected ends to their loop end.
2. The method as set forth in claim 1 wherein the fire resistant sheet has plane front and rear faces and has a serpentine groove in its rear face, further comprising disposing the two halves of the heating wire in parallel with each other while performing the securing step, and wherein the securing step comprises pressing the heating Wire into the serpentine groove.
3. As an intermediate product for use in constructing the combination of a resistance heating wire and a supporting base to which the wire is to be attached in laterally spaced stretches, a heating cable assembly, comprising a doubled over length of electrical heating wire having a loop end and two free ends, the two halves of the wire being arranged in parallel and laterally separable with their free ends being in juxtaposition and permanently connected to non-heating, flexible lead conductors, said assembly, including the doubled over heating wire and said conductors, being coiled in a multiturn package from which it is adapted to be progressively removed, the lead conductors being positioned in the coil to be removed first and the looped end being positioned to be removed last.
4. A heating cable assembly as set forth in claim 3 wherein said lead conductors are the conductors of an insulated cable, said cable having an insulating sheath surrounding both said conductors.
5. The heating cable assembly as set forth in claim 3, further comprising a spool upon which said heating cable assembly is wound beginning at the looped end of the electrical heating wire.
6. A radiant heating panel comprising a sheet of fire resistant material having substantially plane front and rear faces, the rear face having a groove therein for the reception of a heating wire, a heating cable assembly comprising a doubled over length of electrical heating wire having a loop end and parallel halves leading to two free ends, and a pair of insulated electrical conductors connected respectively to the free ends of said heating wire, the heating wire being disposed within said groove and the electrical conductors emerging from the panel for connection to a source of electric current, said groove comprising two parallel channels of serpentine form and the two halves of the heating wire being disposed in parallel along said channels.
References Cited UNITED STATES PATENTS 2,864,931 12/1958 Stoddard et al. 219-535 2,915,615 12/1959 Leipold et a1. 219516 3,062,940 11/1962 Bauer et al 219-544 3,095,491 6/1963 Deacon 219345 2,824,209 2/1958 Leipold 219-528 2,905,918 9/1959 Wagner, Jr. 338210 3,275,803 9/1966 True 219535 3,344,392 9/1967 Briscoe 33963 2,114,396 4/1938 McFarlan et al. 219549X 3,277,273 10/1966 Williams 219345 FOREIGN PATENTS 217,080 11/1956 Australia 219544 VOLODYMYR Y. MAYEWSKY, Primary Examiner US. Cl. X.R.
UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION patent 3,550 ,267 Dated December 29 1970 Inventor(s) Harry ams It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
Column 4, line 6, beginning with "3. As an intermediate cancel all to and including "along said channels." in line same column 4. In the heading to the printed specification, line 8, "6 Claims" should read 2 Claims Signed and sealed this 17th day of August 1971.
EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, Attesting Officer Commissioner of Paten