GB2237105A - Gas fire - Google Patents

Abstract

In a gas fire of the kind incorporating radiant units 3 heatable by flames from a gas burner to produce a source of radiant heat, which heat is supplemented by passing the products of combustion through a heat exchanger 6 which is used to heat further air drawn through the fire by convection, a damper 11 is coupled to openable and closable doors 9 in front of the fire, in such a way as to cause the damper to open on opening of the doors and to close partially on closure of the doors. This results in safer operation of the fire and also increases the thermal efficiency of the fire with the doors closed. With just one of the two doors open, the damper 11 is intermediate the open and partially closed positions. <IMAGE>

Description

Gas Fire This invention relates to gas fires of the kind incorporating radiant units heatable by flames from a gas burner to produce a source of radiant heat, which source of heating is supplemented by passing the products of combustion through a heat exchanger which is used to heat further air drawn through the fire by convection, the products of combustion passing from the heat exchanger to a flue outlet.

It has been proposed to provide such a fire with one or more doors in front of the radiant units, commonly of heat resistant glass, which doors can be closed to reduce the amount of heat radiated into the room, or opened to increase the amount of radiated heat.

In accordance with the present invention a gas fire of the kind referred to, fitted with one or more such doors, incorporates a damper disposed in the path of the products of combustion through the flue outlet and movable to vary the flow of such products from said outlet, the damper being coupled to the door or doors by means of a linkage mechanism which causes the damper to open on opening of the door or doors, and partially to close on closure of the door or doors.

Such an arrangement allows the fire to function safely both in the open and closed positions of the door or doors, and also increases the thermal efficiency of the fire with the door or doors closed, by restricting the flow of the combustion products from the flue outlet.

In the case where the fire is fitted with two doors, the linkage mechanism is conveniently such as to produce a limited movement of the damper to the open condition when one door is open, and a further movement of the damper to its fully open condition with both doors open.

Preferably the damper is biased towards its fully open position, for example under gravity, acting on a weighted part of the linkage mechanism.

The invention is especially, though not exclusively, concerned with decorative gas fires in which a refractory mass, resembling solid fuel such as coal or logs, is heated by the gas flames to give the appearance, when lit, of a solid-fuel fire.

One gas fire in accordance with the invention, incorporating a pair of doors which can be closed to reduce the amount of radiant-heat from the fire, will now be described by way of example with reference to Figures 1 to 3 of the accompanying drawings, in which Figures 1 and 2 illustrate sectional perspective views of the fire with the doors in different positions, and Figure 4 represents an exploded view of a linkage mechanism employed in the fire.

Referring now to the drawings the fire comprises a casing 1 incorporating, adjacent the front, a burner 2 arranged to direct gas flames rearwardly on to refractory radiant elements 3 in the form of imitation coal modules supported on a refractory base 4. The hot flue gases pass upwards through ducts 5 into a heat exchanger 6 and then through an opening 7, which constitues the flue outlet. The casing 1 also has inlets (not shown) which allow air to be drawn into the fire by convection and pass over the heat exchanger 6 so as to be heated by the flue gases, the heated air being discharged back into the room accommodating the fire through louvres as at 8.

The front of the fire is fitted with twodoors 9 of heat resistant glass, which can be closed to reduce the amount of heat radiated from the fire, direct radiant heat then being converted to convected heat.

The flue outlet 7 is associated with a movable damper flap 11 whose position can be altered to vary the flow of flue gases through the flue system. Movement of the damper flap 11 is achieved, in accordance with the invention, by means of a linkage mechanism shown in more detail in Figure 3.

This comprises a main lever 13 pivoted at 14 about-a horizontal pin 15. The front end of the lever 13 is formed with a flange 16 carrying a shouldered adjusting screw 17; the narrow upper end of which fits into an opening in a toggle bridge 18 in the form of a flat plate which rests on the shoulder of the screw 17. The two ends of the toggle bridge 18 carry projections 19 which extend into openings 21 in respective toggles 22 pivoted at 23 about pins 24 carried by a bracket 25 fixed to the casing 1. The front ends of the toggles 22 are shaped as cams 26 such as to cause upward pivoting movement of the toggles as the respective doors 9 are closed. This results in a downward movement of the toggle bridge 18, and an upward pivoting of the rear end of the lever 13.This bears on a weighted cross bar 27 fixed between the rear ends of two further levers 28 pivoted at 29 about respective pins 31, the front ends of which levers 28 carry inward projections 32 engageable with the under surface of the damper flap 11.

With both doors 9 open, the front ends of the respective toggles 22 drop down, and the resultant lifting of the toggle bridge 18 allows the weighted cross bar 27 to depress the rear end of the lever 13, simultaneously raising the front ends of the further levers 28, thereby fully opening the damper flap 11, and allowing maximum passage of the flue gases through the flue system.

When only one of the doors 9 is open, one of the toggles 22 will still be in the raised position as in Figure 1, and the central part of the toggle bridge 18 which rests on the shoulder of the adjusting screw will only be partially raised. Accordingly the weighted cross bar 27 will only be permitted to drop down over part of its full range of movement, and the damper flap 11 will then only be opened to a limited extent.

However with both doors 9 closed, as in Figure 2, and both toggles 22 raised, the rear end of the lever 13 will raise the weighted cross bar 27 to its maximum extent, allowing the damper flap 11 to move to a "closed" position. The arrangement is however such as to leave a small gap through which flue gases can still pass through the flue outlet opening 7 albeit to a limited extent.

This allows the fire to function safely with the doors 9 open or closed, and increases the thermal efficiency of the fire when the doors are closed by restricting the flow of flue gases from the flue outlet opening 7.

Claims (6)

1. A gas fire of the kind referred to, fitted with one or more such doors, including a damper disposed in the path of the products of combustion through the flue outlet and movable to vary the flow of such products from said outlet, the damper being coupled to the door or doors by means of a linkage mechanism which causes the damper to open on opening of the door or doors, and partially to close on closure of the door or doors.

2. A gas fire as claimed in claim 1, in which the fire is fitted with two doors, the linkage mechanism being such as to produce a limited movement of the damper to the open condition when one door is open, and a further movement of the damper to its fully open condition with both doors open.

3. A gas fire as claimed in claim 1 or claim 2, in which the damper is biased towards its fully open position.

4. A gas fire as claimed in claim 3, in which the damper is biased towards its fully open position due to gravity acting on a weighted part of the linkage mechanism.

5. A gas fire as claimed in any one of claims 1 to 4, in which a refractory mass, resembling solid fuel such as coal or logs, is heated in use by the gas flames to give the appearance, when lit, of a solid-fuel fire.

6. A gas fire substantially as herein described with reference to the accompanying drawings.