GB2371849A

GB2371849A - Flue gas extractor for gas fire

Info

Publication number: GB2371849A
Application number: GB0027932A
Authority: GB
Inventors: David Strickland
Original assignee: MAGIGLO Ltd
Current assignee: MAGIGLO Ltd
Priority date: 2000-11-15
Filing date: 2000-11-15
Publication date: 2002-08-07
Also published as: GB0027932D0

Abstract

The extractor unit 12 is fitted to an exterior wall 13 of a building and comprises a fan within a housing 11, which draws flue gas through a duct 22 and discharges into an exit chamber 17 and then to atmosphere via exhaust ports 18 and 19. Wind pressure rise at one port causes air to flow to the other port rather than causing a back draught through the fan. Ports 18 and 19 may face different directions and may be in the side or end walls of the chamber 17 with the fan outlet in the top wall 15 of the chamber 17.

Description

EXTRACTOR FAN UNITS FOR DOMESTIC GAS FIRES

This invention relates to an extractor fan unit for a domestic gas fire in which flue gases from a combustion region of the fire are drawn by an extractor fan along a flue duct that passes through an external wall of a building in which the fire is installed.

This type of extractor unit is often used when a domestic gas fire is installed in a room not having a chimney. A problem that occurs with such units when installed on an external wall is that certain atmospheric conditions, particularly associated with high winds, can create a back draught from the extractor fan to the flue outlet of the fire. This in turn creates an annoying draught in the room in which the fire is installed. Moreover, if the fire is burning, the back draught may be sufficient to reverse, or at least reduce to a dangerous level, the outward flow of the flue gases along the flue duct. In an effort to overcome this problem it is known to provide the outlet of the extractor fan with a baffle that diverts air away from the outlet, but such baffles add to the cost and complexity of the unit and have not been entirely successful in overcoming the problem.

According to the present invention there is provided an extractor unit for fitting to an external wall of a building for extracting flue gases from a combustion region of a domestic fire installed within the building, the extractor unit having an extractor fan with a suction inlet for receiving flue gases and an outlet through which the flue gases are discharged into an exit chamber, the exit chamber being formed with at least two exhaust ports through which the flue gases are exhausted to the atmosphere. Should atmospheric conditions arise in which the air pressure at one of the exhaust ports increases relative to the air pressure at one or more of the other exhaust ports, this simply creates a flow of air in the exit chamber between the ports rather than a back draught through the fan.

Preferably at least two of the exhaust ports in the exit chamber face in different directions.

By way of example only, an extractor unit embodying the invention will now be described with reference to the accompanying drawings wherein:

Fig. 1 is a perspective sketch of the extractor unit, Fig. 2 is a diagrammatic sectional view (on a smaller scale) through the extractor unit when secured to an outside wall, and Fig. 3 is a perspective view of the exit chamber.

Referring to these drawings, the extractor unit consists of a motor (not shown) within a motor housing 10 driving an extractor fan (not shown) about a generally horizontal axis. The fan rotates about the horizontal axis within a fan housing 11 disposed within a support structure 12 (Fig. 2) that is recessed within an external wall 13 of a building in which a domestic gas fire is installed. The support structure 12 has flanges which are secured to the wall 13 such that the unit is supported some distance above the ground. Alternatively the support structure could be bolted directly to the outside of the wall.

The fan housing 11 has a rearwardly facing suction inlet 21 connected to a gather 24 leading to a flue duct 22 (Fig. 2) which is connected to the gas fire. The gather 24 is bounded by a rear plate 25 that is secured to the rear of the support structure 12. Flue gases are drawn along the duct 22 by rotation of the fan.

The fan housing has a downwardly facing outlet 15 through which the flue gases are exhausted. The outlet 15 is located in the top wall 16 of an exit chamber 17, and the flue gases are then discharged into the atmosphere through either one of two exhaust ports 18,19 at opposite ends of the chamber A mesh screen 20 is fitted in each of the ports 18,19, and the entire assembly may be protected by a cover (not shown).

The advantage of providing an exit chamber with two exhaust ports 18,19, rather than discharging the flue gases directly into the atmosphere through the fan outlet 15, is that should the outside air pressure at one of the ports 18,19 increase relative to the pressure at the other port, there will be a flow of air through the exit chamber rather than a flow of air back into the fan. This effectively prevents the creation of back draughts in a room in which the gas fire is installed, particularly when the fire is not burning. Since the two ports 18,19 are arranged to face in different directions, preferably at around 90'to one another, the unit functions effectively when the wind is blowing in different directions.

The unit is effective in extracting flue gases from a gas fire while preventing back draughts through the fan, and it achieves this in a simple manner without the need for auxiliary baffles which might otherwise adversely affect the performance of the fan.

Claims

CLAIMS :

1. An extractor unit for fitting to an external wall of a building, the unit extracting flue gases from a combustion region of a domestic gas fire installed within the building, the unit comprising an extractor fan with an inlet for receiving the flue gases and an outlet through which the flue gases are discharged into an exit chamber, the exit chamber being formed with at least two exhaust ports spaced apart from one another through which the flue gases are exhausted to the atmosphere; and the arrangement being such that, with the unit fitted to the wall, an increase in the atmospheric air pressure at one of the exhaust ports relative to the corresponding pressure at one or more of the other ports creates a flow of air between the ports

2. An extractor unit according to claim 1 wherein at least. two of the exhaust ports face in different directions.

3. An extractor unit according to claim 1 or claim 2 wherein the outlet of the extractor fan is located in a top wall of the exit chamber, and the exhaust ports are located in respective side or end walls of the exit chamber.

4. An extractor unit according to claim 1 and substantially as herein described with reference to the accompanying drawings.