GB2202622A

GB2202622A - An exhaust flue unit for a gas fire

Info

Publication number: GB2202622A
Application number: GB08803145A
Authority: GB
Inventors: Keith Charles Law
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-02-12
Filing date: 1988-02-11
Publication date: 1988-09-28
Anticipated expiration: 2008-02-11
Also published as: GB2202622B; GB8803145D0

Abstract

An exhaust flue unit for a live fuel effect gas fire 3 comprises a housing 21 for supporting the gas fire 3, and a flueway 23 arranged adjacent a convection chamber 31. Exhaust from the gas fire is drawn through the flueway by an extractor fan to vent the fumes and to heat air in the convection chamber. The flueway includes control means for switching off the gas supply to the fire if the flow of exhaust in the flueway falls below a pre-determined acceptable level. The gas fire is arranged to heat a reflector portion 2 of the housing from which heat is transferred to the air in the convection chamber <IMAGE>

Description

AN EXHAUST FLUE UNIT FOR A GAS FIRE This invention relates to an exhaust flue unit for a gas fire. Gas fires are often used for heating an area in a domestic dwelling or in a public place such as a public house, hotel or restaurant and may be used as a supplementary source of heating and to provide a visually attractive effect.

In recent years live-fuel-effect (LFE) gas fires have become increasingly popular but unlike the usual convector-type gas fires provide relatively little convected heat.

Also the venting of fumes from such a fire can be a problem and it has been necessary to install an LFE fire in an existing fireplace with a functional chimney in the fabric of the fireplace to allow the fumes to excape.

Sites without chimneys such as modern houses cannot therefore safely accommodate an LFE fire.

An object of a first aspect of the invention is to overcome thi5problem .

According to the first aspect of the invention there is provided an exhaust flue unit for a live fuel effect gas fire unit comprising a housing for supporting the gas fire, a flueway arranged in or adjacent a convection chamber and means for guiding exhaust from the gas fire through the flueway to vent the fumes and to heat air in the convection chamber.

With such an arrangement air in the convectibnchamber will receive heat from the flueway and inlet and outlet means may be arranged at spaced apart positions on the unit so that the air can rise and leave the outlet to heat the surrounding air.

Preferably, the housing includes a canopy which overhangs the gas fire for capturing the exhaust fumes and the flueway extends from the canopy to a passageway from which the fumes are withdrawn. Preferably the canopy extends beyond the fire at the front to furtlrer assist in the retentiorl of fumes. A plurality of flueways may be provided and the passageway may comprise a manifold which receives the exhaust gas from each flueway.

The convection chamber may be arranged to extend behind a heat reflector portion of the housing which tends to reflect heat from the fire forwardly, the convection chamber being arranged such that air therein can receive heat from said reflector.

The convection chamber may include a plurality of inlets adjacent a base part of the housing and may have a single outlet above the fire.

The exhaust fumes may be drawn through the flueway by an extractor, e.g. a fan. preferably the extractor draws the fumes downwardly through said flueway or flueways.

The fumes are preferably vented from the unit by the extractor at a low level, e.g. adjacent floor level. In that way an exhaust duct for fumes can be laid at skirting board level in a room to enable the duct to be routed to a convenient outlet point remote from the gas fire.

If flow of exhaust, i.e. the rate at which exhaust gases are vented from the flueway, falls below a predetermined acceptable level gas supply is preferably interrupted and a control means such as an electrical control system may be arranged to switch off the gas supply.

According to a second aspect of the invention there is provided an exhaust flue for a gas fire comprising an extractor for drawing exhaust through the flue, and control means responsive. tp the exhaust in. the flue for switching off the gas supply to the fire if the flow of exhaust in the flue falls below a predetermined acceptable level.

Thus, if the extractor fails to draw off a certain amount of exhaust due to non-operation, the gas fire will automatically switch off, removing any likelihood of danger and improving the safety of the gas fire.

This is especially advantageous for those who may not realise that fumes may be building up e.g. the elderly, disabled or children.

The control means may include a flow-responsive element such as a pivotable member. This element may be in association with switch means e.g. a microswitch, which ~~~~~~~~~~~~~ controls a valve in the gas supply to switch off the gas supply.

Alternatively, the control means may be a pressure sensing arrangement. The arrangement may include means for sensing static and/or dynamic pressure of the exhaust flow. The arrangement may include a housing containing movable means e.g. a diaphragm which is movable in response to the sensed pressure. The movable means may be arranged to operate switch means such as a microswitch for controlling a valve in the gas supply.

Again such an arrangement would be fail safe in that unsufficient exhaust flow would result in the gas supply being switched off.

According to a third aspect of the invention there is provided live-fuel-effect gas fire apparatus including means defining a convection chamber through which air is guided into and out of the apparatus and for communicating heat emitted from the fire to air in the convection chamber. Air flowing into the passage will be heated by the fire and returned to the room as a source of convected heat supplementing heat from the flames of the fire.

A flue unit for a live-fuel-effect gas fire according to the first, second and third aspects of the invention is now described by way of example, with reference to the drawings, in which: Figure 1 is a diagrammatic front view of the flue unit; Figure 2 is a sectional view of the flue unit of Figure 1 taken through line A-A of Figure 1; Figure 3 is a sectional view of the flue unit of Figure.

1 taken through line B-B of Figure 1; Figure 3a is a sectional view of the flue unit of Figure 1 taken through line C-C of Figure 1; Figure 4 is a plan view of e exhaust system of the gas fire of Figures 1 to 3; Figure 5 is an end view of the exhaust system of Figure 4; Figure 6 is a perspective view of part of an alternative arrangement for sensing flow of exhaust; and Figure 7 is a plan view of the alternative arrangement.

An LFE gas fire flue 20 consists of an open-fronted cabinet 21 which will usually be accommodated against a wall or in any other location. The cabinet 21 has a canopy 22 over a fireplace space 23 which has a base 1 supporting an LFE gas fire 24. The canopy 22 hangs over the front of the cabinet. Above the base 1 is a heat-reflective breast member 2 for deflecting radiant heat out of the front of the fire.

A flueway 3 is disposed on each side of the base 1 and an inlet passage 4 communicating between the fire and flueway is found on each side of the heat-reflecting member 2. The flueways 3 extend downwardly into an exhaust manifold 5 below the level of the fire to meet a single exhaust pipe 6, which extends externally of the LFE flue to release exhaust to a building vent or directly to the outside of the building in which the LFE fire is installed.

This exhaust pipe 6 is in communication with an electric motor controlled extractor fan 7, which draws out exhaust from the rising flames in the fireplace.

The exhaust system includes flow sensing means such as a pivotable paddle member 8 which is disposed in the exhaust pipe and which pivots from the Fig.4 position in full lines to the broken line position under pressure of fumes flowing through the pipe from the fire. A control box 10 is associated with a main switch (not shown) by which the extractor fan is switched on. The operation of the main switch causes the control box to energise a solenoid operable gas valve 11 which allows gas flow to the normal manually operable inlet valve (not shown) of the fire. To switch on the fire, the user must switch on the main switch before gas can reach the inlet valve. The aforesaid paddle member 8 cooperates with a microswitch 9 of the control box which is activated where the paddle is in the broken line position so that the solenoid of valve 11 remains energised. If the exhaust stops flowing, e.g. by breakdown of the extractor fan 7, the paddle moves to its full position and operates the microswitch thereby deenergising the solenoid of valve 11. The valve 11 then closes and cuts off gas supply to te fire. If the paddle sticks in its full line position, any subsequent attempt to operate the fire will fail. If the mains electricity supply is cut off, the solenoid will not energise. If the paddle 10 sticks in the broken line position when the user switches off the fire and the main switch, the control box circuitry is arranged so that the solenoid cannot subsequently be energised by switching on the main switch. In such a case, the paddle must first be freed before the gas fire can be operated. The system is therefore fail-safe.

An alternative arrangement for sensing the flow of exhaust gas is shown in Figs.6 and 7. Instead of using the paddle 8, two tubes 50, 52 are provided in the exhaust pipe either upstream or downstream of the extractor fan 7. In Figs. 6 and 7 the tubes are shown in an exhaust pipe section 53 downstream of the extractor fan 7.

Tube 50 senses the static pressure P1 of the exhaust passing through the section 53 and the tube 53 points towards the oncoming exhaust thereby sensing dynamic pressure P2 of the exhaust. The tubes 50, 52 are connected to a sensor indicated generally at 55. The sensor includes a gas tight housing 56 containing a flexible diaphragm 57. Tube 50 communicates with the interior of the housing 56 on one side of the diaphragm 57 and the tube 52 communicates with the interior of the housing on the other side of the diaphragm 57. The diaphragm 57 has a reinforcement plate 58 at its centre fast with an operating rod 59. The operating rod 59 passes sealingly through the housing and is arranged to co-operate with an operating lever 60 of the microswitch 9.As exhaust is extracted by the fan 7 so as to flow in the direction of arrows 70 in Fig.6, the dynamic pressure P2 sensed by the tube 52 will be greater than the static pressure P1 sensed by tube 50 and the diaphragm 57 will move to the position shown in Fig.7, thereby maintaining the microswitch 9 in a "switched on" condition. If exhaust flow ceases, or the flow rate falls below an acceptable level, the dynamic pressures P1 and P2 will become equal or will approach each other thereby causing the diaphragm 57 to move downwardly until the microswitch 9 is switched off so as to de-engage solenoid valve 11. The previously described paddle 8 may also be arranged to switch off the microswitch 9 if the exhaust flow rate falls below an acceptable level.

As mentioned before, operation of the main switch switches on the extraction fan 7. Therefore the microswitch 9 will be moved to a switqhed-on position by the diaphragm 57 as a result of air flowing through the exhaust before gas can flow to the inlet valve.

If desired, only one tube 50 or 52 may be provided to sense static or dynamic pressure and the sensed single pressure may be used to move the diaphragm 57; the other side of the diaphragm being open to atmospheric pressure. The diaphragm occupies the broken line position when exhaust flow ceases.

A most advantageous feature of the flue unit is that it provides for the convection of heated air into the space in which the gas fire is located. This is achieved by providing a convector chamber 30 (see Figs.

3 and 3a) which extends in the form of narrow passageway 31 extending upwardly and across the back of the housing and two side passageways 32 which house the flueways 3. The chamber 30 is defined between rear and side panel sections 33, 34 and inner panel sections 35,36. The flueways 3 extend behind L-shaped covers 37 on the panel sections 36. The passageway 31 extends behind the breast member; 2 (as shown clearly in Fig.2) so that air in the convector chamber receives heat therefrom. Three inlets 38, 39, 40 are provided immediately above the base 1 and the chamber 30 has an outlet 42 extending across substantially the full width of the unit. The outlet 42 is in the roof of the unit above the canopy 22 leading out of the front of the cabinet 21 to the room.

The LFE gas fire flue normally operates as follows: The flames of the fire burn and rise upwardly, the flames being visible from the front of the unit and giving heat out from the front of the fire assisted by breast member 2. The fumes from the burnt flamers, shown by arrows B, also rise up and are captured by the inside surface of the canopy 22 and guided through the inlet passages 4 into the two flueways 3, as shown by arrows B. The fumes are drawn down through the flueways 3 and out through the exhaust manifold 5 and exhaust pipe 6 by the extractor fan 7 in the exhaust system.

As the fumes are drawn down through the flueways 3, heat therefrom heats the air in the convector chamber 30. The air in the convector chamber is also heated by the breast member 2 which is heated directly by the fire. The heated air in the convector chamber 30 moves upwardly as shown by arrows C and through the outlet 42 above the canopy 22 as shown by arrows D, the rising air causing cooler air to be drawn in through the inlets 38,39 and 40 as indicated by arrows A.

The extracted fumes can be exhausted directly through an outside wall to the ambient air if such a wall is immediately adjacent the fire. Where the fire is located away from an outside wall, the exhaust pipe may comprise a length of ducting and/or pipework which passes around the base of various walls of a room in which the fire is located to a convenient outlet position.

This feature is particularly useful as the user does not have to position the fire against an outside wall, or a solid structure, i.e. wall, partition or the like. Therefore a flue unit in accordance with the invention renders LFE gas fires open to use by those who have no existing chimney outlet.

Claims

1. An exhaust flue unit for a live fuel effect gas fire unit comprising a housing for supporting the gas fire, a flueway arranged in or adjacent a convection chamber and means for guiding exhaust from the gas fire through the flueway to vent the fumes and to heat air in the convection chamber.

2. An exhaust flue unit as claimed in claim 1, wherein the housing includes a canopy which overhangs the gas fire for capturing the exhaust fumes and the flueway extends from the canopy to a passageway from which the fumes are withdrawn.

3. An exhaust flue unit as claimed in claim 2, wherein the canopy extends beyond the fire at the front to further assist in the retention of fumes.

4. An exhaust flue unit as claimed in claims 2 or 3, wherein a plurality of flueways are provided.

5. An exhaust flue unit as claimed in claim 4 wherein the passageway comprises a manifold which receives the exhaust gas from each flueway.

6. An exhaust flue unit as claimed in any preceding claim, wherein the convection chamber is arranged to extend behind a heat reflector portion of the housing which tends to reflect heat from the fire forwardly, the convection chamber being arranged such that air therein can receive heat from said reflector.

7. An exhaust flue unit as claimed in any preceding claim, wherein the convection chamber includes a plurality of inlets adjacent a base part of the housing.

8. An exhaust flue unit as claimed in any preceding claim, wherein the convection chamber has a single outlet above the fire.

9. An exhaust flue unit as claimed in any preceding claim, wherein the exhaust fumes are drawn through the flueway or flue ways by an extractor.

10. An exhaust flue unit as claimed in claim 9, wherein the extractor is a fan.

11. An exhaust flue unit as claimed in claim 9 or claim 10, wherein the extractor draws the fumes downwardly through said flueway or flueways.

12. An exhaust flue unit as claimed in claim 9, 10, or 11, wherein the fumes are vented from the unit by the extractor at a low level.

13. An exhaust flue unit as claimed in any preceding claim wherein the gas supply to the gas fire is interrupted if the flow of exhaust falls below a predetermined acceptable level.

14. An exhaust flue unit as claimed in claim 13, wherein the gas supply is interrupted by control means, which is arranged to switch off the gas supply.

15. An exhaust flue for a gas fire comprising an extractor for drawing exhaust through the flue, and control means responsive to the exhaust in the flue for switching off the gas supply to the fire if the flow of exhaust in the flue falls below a predetermined acceptable level.

It;l

16. An exhaust flue as claimed in claim15, wherein the control means includes a flow-responsive element.

17. An exhaust flue as claimed in claim 16, wherein the flowresponsive element is a pivotable member.

18. An exhaust flue as claimed in claim 16 or claim 17, wherein the flow-responsive element is in association with switch means which controls a valve in the gas supply to switch off the gas supply.

14cf

19. An exhaust flue as claimed in claim15, wherein the control means is a pressure sensing arrangement.

20. An exhaust flue as claimed in claim 19, wherein the arrangement includes means for sensing static and/or dynamic pressure of the exhaust flow.

21. An exhaust flue as claimed in claim 20, wherein the arrangement includes a housing containing movable means which is movable in response to the sensed pressure.

22. An exhaust flue as claimed in claim 21, wherein the movable means is a diaphragm.

23. An exhaust flue as claimed in claim 21 or claim 22, wherein the movable means is arranged to operate switch means for controlling a valve in the gas supply.

24. Live-fuel-effect gas fire apparatus including means defining a convection chamber through which air is guided into and out of the apparatus and for communicating heat emitted from the fire to air in the convection chamber.