GB2086565A

GB2086565A - Gas-fired radiant heater with integrated electric heating elements

Info

Publication number: GB2086565A
Application number: GB8130992A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-10-15
Filing date: 1981-10-14
Publication date: 1982-05-12
Also published as: FR2492061A1; GB2086565B; FR2492061B1; DE3140700A1

Abstract

A gas-fired radiant heater with integrated electric heating elements is disclosed. The heater comprises a gas heating device (12), an electric heating device (10) and a grill (13) disposed in the front of the heater. The heater is thus selectively gas and/or electric powered, the choice of energy being a function of availability and relative cost. <IMAGE>

Description

SPECIFICATION Gas radiant heater with integrated electric heating elements The present invention relates to a gas radiant heater with integrated electric heating elements which may be selectively used with gas and/or electric power maximise the advantages of available types of energy.

Combination heating apparatus employing gas and electrical power are known such as disclosed in U.S. patents 2,060,079 and 1,998,427.

In accordance with U.S. Patent 2,060,079 the heating apparatus comprises a gas heating unit and a refractory slab in front of which is positioned an electric heating unit provided with pivoted unitary elements which slide in grooves to shift the electric heating unit from its operative position in front of the refractory slab to a rest position therebehind.

In both cases the apparatus comprises two separate heating units movable through mechanical controls which complicates the structure.

U.S. Patent 2,921,176 teaches a gas heater which utilises electric power and from its title "Gas electric heating device" would seem to be a gas and electric heating device but in fact is a gas heater equipped with an electric combustion catalyst device.

The invention on the other hand relates to a gas radiant heater which has integrated electric heating elements and which provides, without any mechanical shifting, rational use and independent or simultaneous use of two types of energy to take into account various factors such as night rates and seasonal factors, and which eliminates in a radiant heater the effect of convection currents which would otherwise have a cooling effect and thereby reduce the efficiency of the heater.

To achieve the above-defined objectives, the gas radiant heater with integrated electric heating elements having a gas heating device and an electric heating device with at least one electrical resistance is characterised in that the devices are combined in a radiant heat emitting unit and anticonvection means is disposed on the front of the heater.

According to a preferred embodiment; - the radiant heat emitting unit comprises a porous or perforated panel of refractory material, namely metal, to which is fixed or in which is incorporated at least one electrical resistance, and the anticonvection means comprises a grill made of metal or other refractory material, disposed on the outside of the heater and having the additional function of providing a secondary radiant heat emitter;; - the electric heating device and the radiant heat emitter member are combined into a porous or perforate panel composed of an electrically conductive refractory material, namely stainless steel, glass or ceramic having electrically conductive properties, and the anticonvection means comprises a grill formed of a metal or other refractory material disposed on the outside of the heater and having the additional function of providing a secondary radiant heat emitter; -the electric heating device comprises resistances spaced from one another and defining at the same time the anticonvection means;; - the gas heating device comprises a perforated or porous combustion gas outlet panel made of refractory material defining a first radiant heat emitter and the electric heating device disposed in front of the panel comprises a plate formed of an electrically conductive material and defines a second radiant heat emitter, the said plate being provided with perforations to carry out the function of the anticonvection means; - in the case the heater has a tubular configuration the radiant heat emitter member comprises a tubular member of porous or perforated refractory material, in the outer surface of which are formed grooves for receiving electrical resistances, the emitter being surrounded at a distance by a tubular sleeve of refractory material provided with openings, acting as the anticonvection means.

These and other advantages and features of the invention will be brought out in the description which follows, given by way of non limiting example, with reference to the accompanying drawings, in which: Figure lisa diagrammatic showing of the structural principle of the radiant heater embodying the invention; Figure 2 diagrammatically illustrates a simple structure of a radiant heater embodying the invention; Figure 3 diagrammatically shows the composite assembly formed by the radiant heat emitter member and the resistances for a heater of tubular configuration; Figures 4 and 5 diagrammatically illustrate other embodiments of the composite assembly of the emitter member and the resistances; and Figures 6and 7are diagrammatic perspective views, partly cutaway, of two other embodiments of the heater.

The structural principle of the heater embodying the invention is schematically shown in Figure 1. The heater comprises a radiant heat emitter member C which may be heated either by a gas heating device A or an electric heating device B with electrical resistances, and to eliminate the effect of convection currents anticonvection means schematically represented at D by a dashed line is provided on the front of the heater.

The gas heating device A is of a conventional type and essentially comprises a heat-insulating enclosure and a flat or tubular gas burner depending on the configuration of the heater.

The electric heating device may have various configurations, such as the following: a) an iron-chromium aluminium heating element placed inside a quartz tube; it is possible to provide power of 1000 to 4000 watts (860 to 3440 kcal/h) for lengths ranging from 0.5m to 1.40m, the emission temperature being 1000 to 11000C; b) a nickel-chromium element embedded in magnesium and cladded, the cladding of refractory inoxidible alloy permits a temperature of 700 to 800"C to be reached with a power of 1000 watts (860 kcal/h) for a length of one metre; c) a nickel-chromium or"kantal" element wound bear around an insulating support (ceramic or mica), the element being in the form of a coiled wire or a ribbon and the temperature being generally limited to 10000C; and d) an electrically conductive glass-panel whose temperature is of the order of 200 to 3000C for a power of 145 watts/dm2 (125 kcal/h dm2) the back of the panel being heat insulated with a glass-wool padding.

It goes without saying that the above numerical examples in no way limit the present invention.

The radiant heat emitter member is very important since it must produce radiant heat during heating by the gas heating device and during heating by the electric heating device.

In Figure 2 is shown in its simplest form an embodiment of the radiant heater. It comprises a heat-insulating enclosure 1 in which is accommodated a gas burner, not shown, the heater comprising, on the heat emitting side, a flat porous or perforated ceramic panel with small channels, which acts as the radiant heat emitter member and comprises an embedded electrical resistance 3 of serpentine configuration. Further, in front of this assembly is provided an anticonvection grill, not shown in Figure 2 but corresponding to what was schematically illustrated and designated by reference D in Figure 1.

In Figure 3 is shown a radiant heat emitter of tubular configuration. It is likewise comprised of ceramic material which is porous or perforated by small channels and is provided with grooves 4 of semicylindrical section which accommodate coiled electrical resistances 5. In the middle of the tubular member is provided a gas burner, not shown in the Figure. There is also provided concentrically with the emitter and outside thereof, an anticonvection grill of tubular shape.

In Figure 4 is shown an alternative embodiment in which the porous or perforated ceramic plate 6 is provided with parallel grooves, e.g., semicylindrical, in which the coiled electrical resistances 7 are accommodated.

In Figure 5 the electric heating device comprises coiled electrical resistances 8 which are held by bars a small distance from the perforate plate 9 of refractory material defining the radiant heat emitter, the assembly formed by these electrical resistances 8 constitute the anticonvection means.

In Figure 6 the coiled electrical resistances 10 are held in position in the grooves connected to the perforated or porous refractory plate 12 by thin webs 11; an anticonvection grill 13 is disposed along the electrical resistances so that it also serves to recover heat and defines a secondary emitter.

Finally, in Figure 7 an interesting solution is depicted in which a porous or perforated plate 14 of ceramic material acts as the primary emitter heated by gas and the electrical emitter is comprised of a perforated plate 15 of electrically conductive material through which the products of the combustion of the gas are exhausted and which at the same time functions as the anticonvection means of refractory material.

The above description therefore shows a gas radiaant heater with integrated electric heating elements which may rationally and efficiently use two types of energy under the best conditions of availability and cost, the heater being of simple and compact structure and having no moving parts.

Obviously the invention is not intended to be limited to the above-described and illustrated embodiments but admits of variations and modifications without departing from the scope of the invention defined by the appended claims.

Claims

1. A gas radiant heater with integrated electrical heating elements and having a gas heating device and an electric heating device with at least one electrical resistance, characterized in that the gas and electrical heating devices are combined in a radiant heat emitter member and anticonvection means is disposed on the front of the heater.

2. A heater according to claim 1, characterized in that the radiant heat emitter member comprises a porous or perforated panel of refractory material, namely metal, to which is fixed or in which is incorporated at least one electrical resistance, and in that the anticonvection means comprises a grill made of metal of another refractory material, disposed on the outside of the heater and having the additional function of providing a secondary radiant heat emitter.

3. A heater according to claim 1, characterized in that the electric heating device and the radiant heat emitter member are combined into a porous or perforated panel of electrically conductive refractory material, namely stainless steel, glass or ceramic having electrically conductive properties, and in that the anticonvection means comprises a grill formed of a metal or another refractory material disposed on the outside of the heater and having the additional function of providing a secondary radiant heat emitter.

4. A heater according to claim 1, characterized in that the electric heating device comprises electrical resistances spaced from one another and defining at the same time the anticonvection means.

5. A heater according to claim 1, characterized in that the gas heating device comprises a perforated or porous combustion gas outlet panel made of refractory material which comprises a first radiant heat emitter and in that the electric heating device disposed in front of the said panel comprises a plate of electrically conductive material and defines a secondary radiant heat emitter, the said plate being provided with perforations to carry out the function of the anticonvection means.

6. A heater according to claim 1, characterized in that the radiant heat emitter comprises a tubular member of porous or perforated refractory material in which are provided grooves for receiving electrical resistances, the emitter member being surrounded at a distance by a tubular sleeve of refractory material provided with openings, acting as the anticonvection means.

7. A gas radiant heater with integrated electric heating elements substantially as herein described and illustrated in Figure 1, Figure 2, Figure 3, Figure 4, FigureS, Figure 6, or Figure 7 of the accompanying drawings.