US3686472A — Space heating apparatus

Claim 1

Independent Claim 24 words

A heating unit as in claim 1, wherein the synthetic resin is selected from the group consisting of a polyester, polyurethane and epoxy resin.

Claim 2

Dependent Claim 83 words

An electrical space heating unit of the storage type comprising at least one electrically conductive sheet resistance provided with circuit leads for connection to a source of current supply, and a rigid cast monolithic mass of electrically insulating refractory material enveloping the resistance, said refractory material containing a synthetic resin, said refractory material being obtained by first treating a synthetic resin with a fire-retarding agent and then mixing the treated resin with an aggregate of calcium silicoaluminate, said aggregate including an aluminous cement.

Claim 3

Dependent Claim 93 words

An electrical space heating unit of the storage type comprising at least one electrically conductive sheet resistance provided with circuit leads for connection to a source of current supply, and a rigid cast monolithic mass of electrically insulating refractory material enveloping the resistance, said refractory material containing a synthetic resin, said refractory material being obtained by first treating a synthetic resin with a fire-retarding agent and then mixing the treated resin with an aggregate of calcium silicoaluminate, said fire-retarding agent being a mixture in equal proportions of antimony oxide and a bromine mixture.

Claim 4

Dependent Claim 28 words

A heating unit as in claim 4, wherein the amount of mixture of antimony oxide and bromine is at least 20 percent by weight of the synthetic resin.

Claim 5

Dependent Claim 93 words

An electrical space heating unit of the storage type comprising at least one electrically conductive sheet resistance provided with circuit leads for connection to a source of current supply, and a rigid cast monolithic mass of electrically insulating refractory material enveloping the resistance, said refractory material containing a synthetic resin, said refractory material being obtained by first treating a synthetic resin with a fire-retarding agent and then mixing the tReated resin with an aggregate of calcium silicoaluminate, the amount of the aggregate being at least 70 percent by weight of the refractory material.

Claim 6

Dependent Claim 24 words

A heating unit as in claim 6, wherein the amount of aluminous cement is at least 2 percent by weight of the calcium silicoaluminate.

Claim 7

Dependent Claim 95 words

An electrical space heating unit of the storage type comprising at least one electrically conductive sheet resistance provided with circuit leads for connection to a source of current supply, and a rigid cast monolithic mass of electrically insulating refractory material enveloping the resistance, said refractory material containing a synthetic resin, said refractory material being obtained by first treating a synthetic resin with a fire-retarding agent and then mixing the treated resin with an aggregate of calcium silicoaluminate, an accelerating agent and a catalyst being added to the treated resin, said accelerating agent being cobalt napthenate.

Claim 8

Dependent Claim 96 words

An electrical space heating unit of the storage type comprising at least one electrically conductive sheet resistance provided with circuit leads for connection to a source of current supply, and a rigid cast monolithic mass of electrically insulating refractory material enveloping the resistance, said refractory material containing a synthetic resin, said refractory material being obtained by first treating a synthetic resin with a fire-retarding agent and then mixing the treated resin with an aggregate of calcium silicoaluminate, an accelerating agent and a catalyst being added to the treated resin, said catalyst being methyl ethyl ketone peroxide.

Claim 9

Dependent Claim 80 words

A heating unit as in claim 1, wherein the sheet resistance comprises a supporting sheet, a plurality of resistance wires secured to the supporting sheet and extending lengthwise thereof in laterally spaced relationship, and a series of conductor bars for connecting adjacent batches of wires in continuous alternation at opposite ends of the supporting sheet so as to provide a continuous multiwire circuit extending in series from end to end of the supporting sheet and terminating in the circuit leads.

Claim 10

Dependent Claim 18 words

A heating unit as in claim 10, wherein the supporting sheet is constituted by a fiber glass mat.

Claim 11

Dependent Claim 17 words

A heating unit as in claim 10, wherein the supporting sheet is constituted by a textile fabric.

Claim 12

Dependent Claim 20 words

A heating unit as in claim 10, wherein the resistance wires are of steel having a resistivity of 40 ohms/ft.

Claim 13

Dependent Claim 19 words

A heating unit as in claim 10, wherein the resistance wires are attached to the supporting sheet by stitching.

Claim 14

Dependent Claim 30 words

A heating unit as in claim 14, wherein the stitching operation is performed by a sewing machine with the wire in the shuttle and a synthetic thread on the spool.

Claim 15

Dependent Claim 54 words

A heating unit as in claim 14, wherein the conductor bars are formed from copper foil, the foil being attached to the end portions of each batch of wires and the corresponding portion of the supporting sheet by the stitching action, the sheet being longitudinally slit between the batches of wires for the purpose.

Claim 16

Dependent Claim 40 words

A heating unit as in claim 16, wherein alternate conductor bars at each end of the support are insulated from each other by a strip of insulating material, the alternate bars passing on to opposite faces of the insulating sheet.

Claim 17

Dependent Claim 25 words

A heating unit as in claim 17, wherein the conductor bars are provided with circuit leads which terminate in sockets embedded in the refractory material.

Claim 18

Independent Claim 112 words

A method of forming a space heating unit, said method comprising treating a synthetic resin with a fire-retarding agent and then mixing the treated resin with an aggregate of calcium silicoaluminate, forming a mastic layer of electrically insulating refractory material containing said synthetic resin in the lower portion of a mould, placing an electrically conductive sheet resistance on the surface of the layer with its circuit leads supported at a predetermined distance from the inner surface of the base of the mould and at a predetermined distance apart, adding a further quantity of said material at least sufficient to encapsulate said resistance, and allowing the whole mass of the material to cure.

Claim 19

Dependent Claim 29 words

A method as in claim 19, wherein the mould is vibrated during the formation of the layer and also during the addition of the further quantity of the material.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1975-08-22	1976-02-21	1976-08-22	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1979-08-22	1980-02-21	1980-08-22	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1983-08-22	1984-02-21	1984-08-22	$7700.00	Window Closed / Lapsed

Space heating apparatus

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