US3428040A

US3428040A - Gas heater

Info

Publication number: US3428040A
Application number: US668468A
Authority: US
Inventors: Ian P S Baker; Kenneth R Wade
Original assignee: United Gas Industries Ltd
Current assignee: United Gas Industries Ltd
Priority date: 1967-09-18
Filing date: 1967-09-18
Publication date: 1969-02-18
Anticipated expiration: 1986-02-18

Description

Filed Sept. 18, 1967 Fe%. 18, 1969 l. P. s. BAKER ET AL 3,428,040

GAS HEATER Sheet of 2 Feb. 18, 1969 I. P s. BAKER ETAL 3,428,040

- GAS HEATER Filed Sept. 18, 1967 Sheet 2 012 A tlorn e 5 United States Patent 3,428,040 GAS HEATER Ian P. S. Baker and Kenneth R. Wade, Liverpool, England, assignors to United Gas Industries Limited, London, England, a British company Filed Sept. 18, 1967, Ser. No. 668,468

U.S. Cl. 126110 Claims Int. Cl. F24h 3/02; F23] 1/00 ABSTRACT OF THE DISCLOSURE The specification describes a balanced flue gas heater, in which the flue pipe is coaxially within the air inlet pipe. The air inlet pipe is provided with an annular seal surrounding its outer end of larger diameter than an exhaust gas deflector assembly on the outer end of the flue pipe. This permits the heater to be installed by simply passing the balanced flue through a hole in a wall from the interior.

This invention relates to gas heaters.

Various forms of gas heaters have been proposed, in which the air for combustion of the gas is drawn in from the exterior of a building, at a point which is closely adjacent the point at which the flue or exhaust gases from the heater are expelled. Such an arrangement is known as a balanced flue. A balanced flue has the advantage that if wind conditions vary the variation is the same on both the combustion air pressure and on the exhaust gas pressure. Thus the burner of the heater may continue to operate satisfactorily without being affected by fluctuations in the external weather conditions.

According to the present invention there is provided a gas heater comprising a burner mounted in a combustion chamber, a balanced flue comprising coaxial outer and inner tubes, the inner tube being connected to the exhaust outlet of the combustion chamber and the annular space between the inner and outer tubes supplying combustion air to the burner, the inner tube extending beyond the outer end of the outer tube, an annular seal surrounding the outer tube, adjacent the outer end thereof, and an exhaust gas deflector at the outer end of the inner tube, such deflector being of a transverse dimension less than the transvers dimension of the annular seal.

With such an arrangement, it is possible to install the balanced flue arrangement of the invention, simply by boring a hole, e.g., by a drill, in an external wall of the building in which the heater is to be mounted. The balanced flue arrangement may then simply be passed through the hole in the wall, from the interior. In a convenient construction, the outer tube is in the form of two telescopically arranged tubes, each provided with an out- Wardly extending flange, the annular seal including at least one resilient ring located between these flanges. If one of the outer tubes is mounted on the rear wall of the heater and the other outer tube is mounted on the inner tube by means of spacers, and the inner tube is adjusted with respect to the rear wall, the two flanges may compress the annular seal, in an axial direction, thus causing radial expansion to seal the flue with respect to the wall.

In a preferred construction, the rear of the heater is formed as a double walled jacket, this jacket being connected to the annular space between the inner and outer tubes, and also being connected to the combustion chamber, so that air passing through the jacket from the annular space flows to supply combustion air to the burner. Thus a continuous flow of cool air passes across the rear of the heater, preventing the wall surface to which the heater is attached from becoming unduly overheated.

The exhaust gas deflector may comprise an outwardly 3,428,040 Patented Feb. 18, 1969 ICC extending annular flange on the outer end of the inner tube, an annular disc mounted co-axially with said inner tube and spaced outwardly from said annular flange, and a cone, mounted co-axially with said inner tube, with its apex towards the tube and spaced from the annular disc. This arrangement provides a particularly simple construction which is eifective in preventing the exhaust gases emanating from the inner tube from flowing back and into the annular space and thus to the burner.

Preferably the heater is of the force draught type, in which air is blown by a fan into the combustion chamber.

In order that the invention may more readily be understood, the following descripti-on is given, merely by way of example, reference being made to the accompanying drawings, in which:

FIGURE 1 is a schematic sectional side elevation of one embodiment of gas air heater according to the invention taken along the line I-I of FIGURE 2; and

FIGURE 2 is a schematic sectional front elevation taken along the line II-II of FIGURE 1.

This embodiment is a domestic gas-fired convector space heater adapted to be installed in a room or space on an outside wall thereof. The heater comprises a sheet metal casing 10 of generally rectangular parallelepipedonal form having a relatively small front to back dimension as compared with its height or side-to-side dimension. In a heater suitable for heating an average sized room or space in a domestic dwelling, a conveniently sized outer casing would be one having a side-to-side width of about 2 feet 6 inches (76.3 cms.), a height of about 2 feet (61 cms.) and a front-to-back dimension of about 5 inches (12.7 cms.).

Within the upper part of the outer casing 10, the heater is furnished with a sheet metal combustion chamber 11 which is a closed unit, except for an inlet 12 for combustion air and an outlet 13 for combustion products. The combustion chamber is extended upwardly at 14, to provide a primary heat exchanger, which is connected at its upper part to a secondary heat exchanger 15 which is spaced from and directly behind the primary hea-t exchanger. The connection between the heat exchanger is effected by two plunged holes 16, forming ducts therebetween, and the outlet 13 is formed in the lower part of the secondary heat exchanger.

Extending horizontally within the combustion chamber from side-to-side of the lower part thereof is a gas burner 17, the supply of gas to such burner being by way of a pipe 18 passing in a sealed manner through the left hand side wall (FIGURE 2) of the combustion chamber. A combined igniter and pilot burner 19, for lighting the burner also passes in a sealed manner through the side wall of the combustion chamber, at a position above the burner 1. A mercury capsule 20 and an auxiliary pilot burner 21 therefor, are positioned below the igniter 19, and act as a flame failure device. The gas pipe 18 and conduits 22, 23 for the said igniter and flame failure device pass downwardly outside the combustion chamber 10 to controls 24, which may be of a conventional form and which are mounted in an end portion of the lower part of the casing. The remainder of said lower part of the casing is mainly taken up by a tangential or crossflow blower 25, for speeding up the convection air flow from a convection air inlet 26 to a convection air outlet 27 at the bottom and top of the 'front wall of the casing. When the blower 25 is roted by motor 28, air is blown over and between the primary and secondary heat exchangers. Adjacent the air inlet 12 of the combustion chamber is mounted a combustion air fan 29, which is of the centrifugal type, and which is driven by an electric motor 30. The inlet to the combustion air fan 29 is from the space between the double skins 31, 32 of the rear wall of the casing 10, which draws its air from an annular passage in a combined flue and combustion air inlet assembly, or balanced flue, positioned at the central region of the rear of the outer casing.

It will be appreciated that the air inlet 12 to the combustion chamber is offset to one side thereof. In order to ensure an even distribution of air to the burner which extends from side-to-side of the combustion space, a baffle 33 extends horizontally within the combustion space below the burner 17. Baflle 33 extends across the whole front-to-rear width of the combustion space and from the side of the combustion spacer nearer to the air inlet to a position near, but spaced from the two sides of the combustion space. The baflle has therein a number of apertures 34 of increasing cross section from right to left, to supply secondary combustion air at an even rate along the length of the burner 17 At its right hand end (FIGURE 1) baflle 33 is bent up to provide an upwardly extending baffle 35 to the left of the inlet aperture 12. Thus air blown into the combustion chamber by fan 29 is divided into two streams, one flowing under baffle 33, and the other being directed along the right hand wall of the combustion chamber to cool it. The air passing under baflle 33 flows through apertures 34 and also through a further aperture 36, to provide primary combustion air for burner 16. The remainder of the air under baflle 33 flows upwardly to cool the left hand wall of the combustion chamber.

The flue outlet from the secondary heat exchanger extends substantially centrally of the lower portion of the back wall thereof. Through this outlet, passes a flue pipe 37 of the combined flue and combustion air inlet assembly 38, referred to above and to enable this flue pipe to have sealing press fit in the flue outlet, around the latter, the rear wall of the secondary heat exchanger and the inner skin of the rear wall of the heater are plunged towards one another and clamp between them a sealing washer of resilient material adapted to receive the flue pipe 37.

The combined flue and combustion air inlet assembly 38 comprises the flue pipe 37 and a pair of telescopically arranged tubes 38, 39 surrounding such pipe and defining with the latter an annular space 40 through which combust-ion air is drawn into the heater via the space between the two skins of the back wall. The tube 38 having the larger diameter is, in use of the heater, nearer to the combustion space and has at its inner end an outwardly projecting flange 41 adapted to abut against the wall 42 on which the heater is to be mounted. Such flange carries a resilient sealing gasket (not shown) against which the surround of a hole 43 in the outer skin of the rear wall of the heater is adapted to abut when the heater is mounted on the flue and air inlet assembly 38. The said flange also has secured thereto a yoke (not shown) through which the flue pipe passes and to which the inner end of the pipe can be secured. The smaller diameter tube 39 fits within the outer end of the larger diameter tube 38 and has intern-ally thereof a plurality of webs or spacers 44 securing the flue pipe centrally Within such tube. Each tube has, at its outer end, an outwardly directed radial flange 45, 46 and between the two flanges are arranged three annular Washers 47 of resilient material, such as polyurethane. At its inner end the flue pipe has two holes 48 by which the flue pipe can be secured to said yoke by a pin (not shown).

The outer end of the flue pipe is provided with an exhaust gas deflector assembly, comprising a flange 49, a flat annular disc 51 and a conical member 52. With this assembly a satisfactory dispersion of the flue or-exhaust gases is effected as they leave the flue pipe. The purpose of the outer end assembly of the balanced flue is to eliminate or reduce the drawing of the flue gases back into the annular space 40, and thus into the combustion chamber, whatever the wind conditions obtaining outside the wall.

In installing the above described heater, a hole is made, for example with a percussion or rotary masonry drill,

in the wall on which the heater is to be mounted, such hole being slightly larger in diameter than the outer diameter of the radial flanges 45, 46 on the outer ends of the telescopic tubes of the flue and air inlet assembly 38, i.e., about 2 /2 inches (6.05 cms.) diameter. The exhaust

gas deflector assembly

49, 51, 52 is slightly smaller in diameter than the annular washers 47, so that the exhaust gas de flector assembly may be passed through the hole in the wall from the interior. The balanced flue and exhaust gas deflector is passed through the hole, from inside the room, until the flange 41 on the inner end of the larger diameter tube engages the inner face of the wall in which the hole has been made. The flue pipe is then pulled inwardly, thereby causing the smaller diameter tube 39 to which the flue pipe is connected, to be telescoped within the larger tube 38, such action causing the annular washers 47 to be axially compressed between the flanges 45 and 46 and at the same time radially expanded into contact with the inner surface of the hole in the wall to secure the assembly in the wall. The flue pipe is secured in this position by a rivet, split pin or similar device being passed through the holes in the yoke (not shown) and appropriately drilled holes 48 in the inner end of the flue pipe, the inner end of the pipe being cut to length as required. The heater is then fixed in position over the protruding end of the flue pipe thus passing sealingly into the outlet 13 of the secondary heat exchanger, and the annular space around the flue pipe being put into communication with the space between the two skins of the rear wall of the heater.

The heater may be thermostatically controlled individually or in combination with a group of heaters in different parts of a house or other structure.

In the embodiment specifically described, the lanced flue assembly projects from the back of the heater and the latter is designed for mounting in a room or space on an outside wall thereof. In a modification, the combined flue and air inlet assembly is designed to project from the side of the heater so that the latter may even be mounted on an internal wall, the said assembly being led to the outside in any appropriate manner. In the latter arrangement, the flue outlet from the secondary heat exchanger will be arranged in the side face thereof.

If desired, the flat annular disc 51 may be omitted from the deflector assembly. This, however, reduces the efficiency of the assembly.

We claim:

1. A gas heater comprising in combination:

(a) a combustion chamber;

(b) a burner within said combustion chamber;

(c) an exhaust gas outlet means for said combustion chamber;

(d) coaxial inner and outer tubes defining therebetween an annular space;

(e) said inner tube connected to said exhaust gas outlet means and said annular space connected to said combustion chamber adjacent said burner effective to supply combustion air to said burner;

(f) an outer end to each of said inner and outer tubes, said inner tube extending axially beyond said outer tube;

(g) an annular resilient seal surrounding said outer tube adjacent said outer end; and

(h) exhaust gas deflector means at the outer end of said inner tube and of a transverse dimension less than the transverse dimension of said annular seal.

2. A gas heater as defined in claim 1 wherein said outer tube is in the form of two telescopically arranged tubes, wherein each of said telescopically arranged tubes is provided with an outwardly extending flange and wherein the annular resilient seal is located between said outwardly extending flanges.

3. A gas heater as defined in claim 2, wherein the heater is provided with a rear wall, and one of said outer tubes is mounted on said rear wall, wherein spacers mount the other of said outer tube on the inner tube and wherein said inner tube is axially adjustable relative to said rear wall.

4. A gas heater as defined in claim 3, wherein the heater is provided with an inner rear wall spaced inwardly from said rear wall and defining therewith a jacket extending across the rear of the heater, a connection between said jacket and said combustion chamber and said annular space between said inner and outer tubes opening into said jacket.

5. A gas heater as defined in claim 1, wherein said exhaust gas deflector means comprises an outwardly extending annular flange on said outer end of said inner tube, an annular disc mounted coaxially with said inner tube and spaced outwardly from said annular flange, and an outwardly divergent cone, mounted coaxially with said inner tube and spaced outwardly from said annular disc.

6. A gas heater as defined in claim 1, wherein said heater comprises a first portion extending upwardly above said burner and a second portion extending adjacent said first portion, an upper part to said first and second portions and a lower part to said second portion, a connection between said upper parts of said first and second portion, said exhaust gas outlet means including an outlet in the lower part of said second portion.

7. A gas heater as defined in claim 6, wherein said first and second portions define therebetween a gap, said heater further comprising a cross flow blower eflective to blow air between said first and second portions, through said gap.

8. A gas heater as defined in claim 1, wherein said burner extends laterally across said heater, and a fan is connected to said inner tube and to said combustion chamber effective to direct combustion air laterally across said combustion chamber towards said burner.

9. A gas heater as defined in claim 8, wherein an upwardly extending baflle is mounted in said combustion chamber between said fan and said burner elfective to divide the fiow of air first downwardly to said burner and second upwardly into said combustion chamber.

10. A gas heater as defined in claim 9, wherein a horizontal bafile is mounted beneath said burner, and apertures are defined in said horizontal baflle.

References Cited UNITED STATES PATENTS 2,632,435 3/1953 Lundstrum 126-85 3,056,397 10/1962 Little 12685 3,263,749 8/1966 Dormitzer 126-110 JAMES W. WESTHAVER, Primary Examiner.

US. Cl. X.R