US3203413A - Infrared heater - Google Patents

Description

Aug. 31, 1965 D. w. HARTZELL ETAL 3,203,413

INFRARED HEATER Filed Aug. 24, 1961 INVENTORS'. pal/440 VL #4272!!! ART/#7? 5 1 005 United States Patent 3,203,413 INFRARED HEATER Donald W. Hartzell and Arthur E. Yoos, Centralia, lll., assignors to Lear Seigler, Inc., a corporation of Delaware Filed Aug. 24, 1961, Ser. No. 133,642

4 Claims. (Cl. 126-92) This invention relates to a gas heater and particularly to a gas infrared heater.

As is generally known, space heating by means of infrared radiations oflfers'in certain installations advantages not attainable through the use of conventional heaters that rely principally upon convection. Due to absorption of infrared radiations by the human body, both general thermal comfort and therapeutic benefits can be effectively attained through infrared heating. Residential bathroom installations offer one example where infrared heating is particularly applicable.

' In a gas infrared heater, it is required that a surface of a burner element be heated to incandescence to serve as a high temperature source of radiant heat. Various burner elements of refractory materials have been developed in which combustion of a fuel mixture occurs near one surface of the element so that such surface is heated to the temperature required to provide infrared radiations. While the range of wave lengths in the infrared band is relatively wide, the wave length of the infrared radiations presently preferred for thermal comfort is between 2.5 microns and 3.5 microns. These wave lengths provide the penetrating quality which produces an optimum degree of body warmth. Wave lengths in the desired range from 2.5 to 3.5 microns are emitted where the heated body is at a temperature of from 155 0 to 1600 F.

The present invention is a gas infrared heater including a burner element having a plurality of passages extending through it from an inner surface to an outer surface. Means are provided for maintaining a combustible fuel mixture of primary air and gas against the inner surface of the burner element to force the fuel mixture through the passages to be burned near the outer surface. Means are provided for conducting secondary air to the burner element. Flow-directing means are spaced apart from the outer surface of the burner element to cause the secondary air to pass across the outer surface of the burner element.

A particular feature of the gas infrared heater of the present invention lies in the flow-directing means disposed in a spaced apart relationship with respect to the outer surface of the burner element, the flow-directing means being of a material such that infrared radiations readily pass through it. It is the outer surface of the burner element which is heated to the temperature required for infrared radiations. It has been found that the provision of the flow-directing means to cause flow of secondary air across the outer surface results in improved and more constant combustion at the outer surface. As a consequence, constant radiation of infrared emissions of desired wave lengths is obtained. It is possible thereby to maintain the temperature of the outer surface of the burner element between 1550 and 1600 F. so that the infrared emissions have a wave length in the range most beneficial for thermal comfort. These operating charac- 3,203,413 Patented Aug. 31, 1965 teristics are obtainable at a gas manifold pressure of 3.5" H 0, the pressure at which gas is normally supplied to residences.

In the gas infrared heater of the present invention, the capacity of a given burner element, in terms of output in B.t.u.s, is increased by approximately one-third as compared to a gas infrared heater in which no flow-directing means for causing flow of secondary air across the burner element is provided. While it is not intended to limit the apparatus of the present invention to a particular theory of operation, it is thought that this unexpected increase in capacity is the result of more complete combustion produced by the continuous removal of combustion products from the surface of the burner element by the flow of secondary air across such surface.

An added advantage of the gas infrared heater of the present invention is that constant radiation of desired infrared emissions is obtained even in environments in which drafts cause variations in the radiations of prior art infrared heaters. This characteristic makes the infrared heater of the present invention useful in warehouses, shops and the like where air currents can seriously impair the utility of prior art heaters.

The structure of the gas infrared heater of the present invention and the manner of its operation will be more fully understood from the following description made in conjunction with the accompanying drawing showing a sectional elevation of one embodiment of the heater.

With reference to the drawing, a vented wall-mounted infrared heater particularly adapted for a residential vided by an aperture 22 located in a horizontal wall of the housing directly above the vertical wall within which the primary air intake is positioned. A grill 24 is fitted within aperture 22. This embodiment of the heater demonstrates the presently preferred practice whereby both primary air and secondary air are derived from the same source so that both are initially at the same temperature and pressure.

A burner assembly, generally indicated by 26, is supported within the housing. cludes a cast iron burner body 28 defining an enclosed chamber 30. A fuel mixture distributor 32 in the form of a tubular member is sealably fitted through the bottom of the burner body so that its lower end is located externally of the burner body and its upper end is Within chamber 30. A semicylindrical section of the portion of the distributor within chamber 30 is removed to provide a fuel mixture outlet 34. An adapter 36 is fitted to the lower end of the fuel mixture distributor. The adapter has air inlet openings in each of its four sides, three of the air inlet openings being shown and identified by reference character 38. An orifice 40 is fitted in the bottom of the adapter and extends within it so that it is centrally positioned with respect to air inlet openings 38. A gas pipe 42 is joined to the orifice at one end and is connected at its other end (not shown) to a source of fuel gas.

The burner assembly in- One wall of the burner body 28 is inclined at an angle of 45 and includes an opening 44. One or more ceramic burner elements 46 are mounted within opening 44. While various burner elements of refractory materials suitable for providing infrared radiations may be used within the scope of the invention, it is presently preferred that burner elements of the type described in US. Patent No.2,775,294 issued December 25, 1956, be used. These elements include a plurality of passage 48 extending from the inher surface 50 of the burner element to the outer surface 52 of the burner element. These elements incorporate a heat-retarding medium to reduce the thermal conductivity of the burner element so that the temperature at the inner surface is less than one-fourth of the temperature of from l550 to 1600 F. at which the outer surface is maintained during combustion. The housing and hood are joined to frame the burner element so that its outer surface is exposed to the space in which the heater is mounted. A pilot light 54, suitably connected to a source of gas, is positioned adjacent outer surface 52 of the burner element. The pilot light shown in the drawing is a schematic representation of a commercially available unit and includes a thermocouple disc 54a dispossed above a lower disc 54b which is rovided with a circularly disposed array of gas jets.

A flow-directing member 56 is supported along its periphery by the housing and is positioned in spaced-apart relationship with respect to the outer surface of the burner element. The flow-directing member is substantially coextensive with the burner element in size. In the presently preferred form, the flow-directing member is mounted so that it diverges slightly from the outer surface of the burner element, the lower end of the flow-directing memher being approximately /2 from the outer surface, and the upper end of the flow-directing member being approximately from the outer surface. The flow-directing member can also be in a parallel spaced-apart relationship with the outer surface of the burner element. Variations in the spaced-apart distance between the flow-directing member and the outer surface of the burner element can be made to produce differeing chimney effects without affecting the basic function of the flow-directing member.

It is essential that the flow-directing member be of a material such that infrared radiations pass through it without substantial absorption of the radiations. In the embodiment shown in the drawing, the flow-directing member is formed from a screen of l8-gauge wire having meshes to each inch. Such a screen is satisfactory in that it transmits infrared radiations while functioning to cause secondary air to flow across the outer surface of the burner element, as will be hereinafter described. In addition, however, other materials, such as, for example, a quartz glass or mica, each of which is capable of transmitting substantially all of the infrared radiations, can be used as the flow-directing member.

A reflector 58 made of highly polished steel is positioned near the lower end of the flow-directing member and is supported by a portion of hood 16. A duct 60 is formed within the housing and is internally fitted to the hood member near the upper end of the flow-directing member to provide a conduit 62 for flow of combustion products. The duct leads to an exhaust 64 which passes through the housing and is connected to a vent 66 in the wall of the residence. Vent 66 is connected so as to discharge gases externally of the residence.

In operation, flow of gas is initiated through line 42 upon opening of a suitable flow control valve. While not shown, a knob or handle for opening and closing such a valve is mounted on the housing of the heater. Flow of gas through orifice 40 pulls primary air, in accordance with well-known principles, through grill and air inlet openings 38 into the adapter to form a combustible mixture of gas and air. The mixture of gas and air flows through distributor 32 and is discharged into chamber through fuel mixture outlet 34. The combustible mixture of gas and air is maintained against the inner surface of burner element 46 so that the existing pressure differential causes the combustible fuel mixture to flow through passages 48 of the burner element. Combustion of the fuel mixture occurs within these passages near outer surface 52 of the burner element.

Hot combustion products tend to rise in the space between outer surface 52 and flow-directing member 56 and pass into duct 62. Secondary air enters the infrared burner of the present invention through grill 24 and rises to the lower end of the burner element. The flow-directing member 56 causes the secondary air to flow across the outer surface of the burner element and pass into duct 62 together with the combustion products. The flow of secondary air across the outer surface of the burner element in the space between the outer surface and flow-directing member 56 purges that region of combustion products. The improved combustion and constant radiation previously described are thereby attained. The outer surface of the burner element can be readily maintained at a temperature of between l550 land 1600 F. so that infrared radiation having the wave lengths most beneficial for thermal comfort are produced.

The arrangment for fiow of secondary air across the outer surface of the burner as herein described is inherently balanced with respect to manifold pressure variations of the gas passing through orifice 40. A decrease in pressure with resulting reduction in the amount of combustion products produces a decreased chimney effect so that less secondary air is drawn across the outer face of the burner element.

In the embodiment shown in the drawing, the ceramic burner elements are positioned at an angle of so that the infrared radiations are directed downwardly to provide full body warmth. It will be understood that the burner elements may also be placed in other positions without affecting the basic operating characteristics of the heater. For example, the heater may be arranged as a ceilingrnounted unit in which the burner elements are parallel to the ceiling. Variations of this nature in the structure of the heater are within the scope of the present invention and derive, together with the embodiment described, the advantages of instantaneous response and low service costs intrinsic in gas heaters, as Well as the improved and constant radiation resulting from the structure of the infrared heater of the present invention.

We claim:

1. A gas infrared heater comprising a housing defining an enclosure, a burner element having a plurality of passages extending therethrough from an inner surface to an outer surface, means mounting the burner element in the housing so that the outer surface of the burner element is inclined to have a vertical component, means for maintaining a combustible mixture of primary air and gas against the inner surface of the burner element for flow of the mixture through the plurality of passages and for combustion of the mixture near the outer surface, intake means spaced below the burner element for intaking secondary air, vent means spaced above the burner element, means capable of transmitting infrared radiations adjacent the outer surface of the burner element and spaced therefrom to promote flow of secondary air across the entire outer surface in close contact with said surface, the lower and upper ends of the outer surface of the burner element being spaced from opposing ends of the infrared transmitting means to provide apertures for entry and exit of secondary air, first passage means enabling flow of secondary air between the intake means and the secondary air entry aperture, and second passage means enabling flow from the secondary air exit to the vent means.

2. Heater in accordance with claim 1 wherein an opposed end of the means capable of transmitting infrared radiations is spaced from the upper end of the outer surface of the burner element a greater distance than the 5 6 other opposed end of said means is spaced from the lower 1,738,335 12/29 Thompson 126-92 end of the outer surface of the burner element. 2,517,071 8/50 Wyatt 12692 3. Heater in accordance with claim 1 in which the 2,936,751 5/60 Forniti 126-92 25:1; capable of transmitting infrared radiations is a 5 FOREIGN PATENTS 4. Heater in accordance With claim 1 in which the 535,753 2/ 55 Belgium means capable of transmitting infrared radiations is spaced 416,474 9/34 Great from about one-half inch to about three-quarters of an 744,980 2/56 l f inch from the outer surface of the burner element. 798,798 7/ 58 Gl'eat Bumm- Refierences Cited by the Examiner 10 JAMES W. WESTHAVER, Primary Examiner.

UNITED STATES PATENTS FREDERICK L. MATTESON, JR., FREDERICK KET- 1,647,995 11/27 Humphrey 126-92 TERER Examine-

Claims (1)

1. A GAS INFRARED HEATER COMPRISING A HOUSING DEFINING AN ENCLOSURE, A BURNER ELEMENT HAVING A PLURALITY OF PASSAGES EXTENDING THERETHROUGH FROM AN INNER SURFACE TO AN OUTER SURFACE, MEANS MOUNTING THE BURNER ELEMENT IN THE HOUSING SO THAT THE OUTER SURFACE OF THE BURNER ELEMENT IS INCLINED TO HAVE A VERTICAL COMPONENT, MEANS FOR MAINTAINING A COMBUSTIBLE MIXTURE OF PRIMARY AIR AND GAS AGAINST THE INNER SURFACE OF THE BURNER ELEMENT FOR FLOW OF THE MIXTURE THROUGH THE PLURALITY OF PASSAGES AND FOR COMBUSTION OF THE MIXTURE NEAR THE OUTER SURFACE, INTAKE MEANS SPACED BELOW THE BURNER ELEMENT FOR INTAKING SECONDARY AIR, VENT MEANS SPACED ABOVE THE BURNER ELEMENT, MEANS CAPABLE OF TRANSMITTING INFRARED RADIATIONS ADJACENT THE OUTER SURFACE OF THE BURNER ELEMENT AND SPACED THEREFROM TO PROMOTE FLOW OF SECONDARY AIR ACROSS THE ENTIRE OUTER SURFACE IN CLOSE CONTACT WITH SAID SURFACE, THE LOWER AND UPPER ENDS OF THE OUTER SURFACE OF THE BURNER ELEMENT BEING SPACED FROM OPPOSING ENDS OF THE INFRARED TRANSMITTING MEANS TO PROVIDE APERTURES FOR ENTRY AND EXIT OF SECONDARY AIR, FIRST PASSAGE MEANS ENABLING FLOW OF SECONDARY AIR BETWEEN THE INTAKE MEANS AND THE SECONDARY AIR ENTRY APERTURE, AND SECOND PASSAGE MEANS ENABLING FLOW FROM THE SECONDARY AIR EXIT TO THE VENT MEANS.

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