A METHOD OF AND A DEVICE FOR MECHANICALLY REMOVING GAS FROM A ROOM SPACE

Abstract: A method of removing harmful gases from a room (4) by sucking the gases through a gas flue (6) in which suction is created by means of an injection effect produced by a flow of air (A) fed from outside the gas flue by means of a fan (1). In order to be able to use the same fan for the ventilation of the room, the air for the injection effect is taken from an exhaust duct (8) for indoor air. In a device for realizing the method, the fan outlet communicates with an injector nozzle (10) projecting into the gas flue, and the fan inlet communicates with the exhaust duct for indoor air, so that the fan operates as a combined gas removal and ventilation fan.

Description: A method of and a device for mechanically removing gas from a room space This invention relates to a method of mechan- ically removing gas from a room space, wherein - harmful gases are removed from the room space by sucking them through a gas flue in which suction is created by an injection effect produced by a flow of air passed from the side of the flue into the flue by means of a fan; and - exhaust air is removed from the room space by sucking it through an exhaust air duct. To increase the suction effect, the gas flues of open fireplaces are commonly provided with a suction-type fan which is mounted at the top of the chimney directly on the gas flue in such a way that hot flue gases flow sidewardly out of the flue under the influence of the centrifugal force of the fan, while the motor of the fan remains outside the flow of flue gases. This kind of fireplace fan operates well when lighting the fireplace, but after the fire¬ place has warmed up and the chimney effect has been created, it should be possible to switch off the fan or to reduce its power as otherwise the suction is too great, and the fan is disturbingly noisy. The fan, however, cannot be switched off, because the motor of the fan will burn if the cooling of the motor is not in operation. The fireplace fan is of special structure and therefore expensive. In addition, the gas flue is difficult to clean as the fan blocks the flue, thus preventing sweeping. To overcome these problems, it has been suggested to create suction in the gas flue by means of an injection effect created by a flow of air passed into the flue. In this way the gases to be removed are brought into motion by the suction created by the injection nozzle, whereby the required flow of air can be produced on the side of the gas flue. As a consequence, the fan does not come into contact with the gases, so that it need not be of any special structure, but a simple cheap standard fan of series production can be used. The power of the fan can be reduced as desired, and the fan can even be switched off during operation without any risk of the burning of the bearing and the motor of the fan. A disadvantage of this kind of solution is, however, the need of a separate fan, which rises the cost of the gas removal system of the fireplace. The object of the present invention is to pro- vide a method which avoids the need of a separate fan. This object is achieved by means of a method of the invention which is characterized in that the air for the injection effect is passed into the flue by means of the fan selectively from the exhaust air duct and/or from outdoor air. This method is based on the idea that the fan which is used for the removal of harmful gases, such as flue gases from the fireplace, is also used for the ventilation of the room space, or in other words, the suction required for the removal of harmful gases, such as flues gases from the fireplace, is created with a fan already used for removing exhaust air from the room space. In this way, a single fan operating as a combined gas removal and ventilation fan is sufficient. The invention is also concerned with a device for applying the above-mentioned method. This device is characterized by what is disclosed in claim 3. The device provides the advantages mentioned in con- nection with the method. In the following the invention will be described in greater detail with reference to the attached drawing, in which Figure 1 illustrates schematically the oper- ating principle of the method according to the inven¬ tion as well as the structure of a device developed for applying the method; and Figure 2 is a perspective view of the fan portion of the device when mounted upon a chimney. The removal device shown in the drawing com¬ prises a fan 1 mounted in a housing 2 attached upon a chimney 3, Figure 2, in the vicinity of a gas flue 6 of a fireplace 5 in a room space 4. A fan inlet 7 communicates with an exhaust air duct 8 forming a part of the ventilation system of the room space. A fan outlet 9, in turn, communicates with an injector nozzle 10 which projects into the gas flue and the discharge opening of which opens upwards. The nozzle is surrounded with a covering 11 provided with a spark catcher. A bypass duct 13 leading into outdoor air and provided with a damper 12 is connected be¬ tween the fan outlet and the nozzle. The fan outlet communicates with an outdoor air supply duct 15 provided with a damper 14. During the operation of the fan, a flow of air A from the injector nozzle creates draught in the gas flue of the fireplace. This draught sucks the flue gases out of the chimney. By means of the damper 12, part of the air blown by the fan can be passed directly into outdoor air through the bypass duct 13 and thus affect the suction effect of the injector. The fan sucks the air that it needs from the exhaust air duct 8 of the room space, thus simulta¬ neously operating as a removal fan for the ven- tilation system. By means of the damper 14, part of the air can be taken directly from the outdoor air supply duct 15. It is noted that a single fan suffices both for the fireplace and for the ventilation operations of the building. Hot gases from the fireplace do not flow through the fan. Turning of the damper 12 into its fireplace position results in a reduction in the ventilation in general, which, in fact, is desirable as the room air is to be exhausted through the gas flue together with smoke. By suitably shaping the injector nozzle, the ventilation system of the build¬ ing can be maintained in balance even though the use of the fireplace fan is intermittent. To facilitate easy cleaning of the flue, the injector nozzle is shaped or positioned in such a manner that the opening of the gas flue remains free, e.g. by using an annular nozzle or by securing the nozzle to the edge of the flue. The fan speed can be adjusted by a potentio- meter 16 to achieve adequate draught in the gas flue. The drawings and the description related to them are only intended to illustrate the idea of the invention. In their details, the method and the device of the invention may vary within the scope of the claims. The device can be used in industrial processes at exhaust points for hot gases, explosive gases, gases contaminating the fan, dust and the like.

Claims: Claims: 1. A method of mechanically removing gas from a room space (4), wherein - harmful gases are removed from the room space by sucking them through a gas flue (6) in which suction is created by an injection effect produced by a flow of air (A) passed from the side of the flue into the flue by means of a fan (1); and - exhaust air is removed from the room space by sucking it through an exhaust air duct (8), c h a r a c t e r i z e d in that the air for the injection effect is passed into the flue (6) by means of the fan (1) selectively from the exhaust air duct (8) and/or from outdoor air (15). 2. A method according to claim 1, c h a r a c ¬ t e r i z e d in that part of the air from the ex¬ haust air duct (8) is passed into outdoor air (13) before the gas flue (6). 3. A device for removing gas from a room space (4) through a gas flue (6), comprising a fan (1) mounted to the side of the gas flue and having an outlet (9) communicating with an injector nozzle (10) projecting into the gas flue (6) and an inlet (7) communicating with a source of air (15) positioned exteriorly of the gas flue (6) to create a flow of air (A) which causes a suction effect in the gas flue, an exhaust air duct (8) being provided for the room space (4) for mechanical ventilation of the room space, c h a r a c t e r i z e d in that the inlet (7) of the fan (1) communicates with the exhaust air duct (8) for the room space (4). 4. A device according to claim 3, c h a r a c ¬ t e r i z e d in that the inlet (7) of the fan (1) communicates with a supply duct (15) for outdoor air by means of a damper (14) which selectively connects the fan inlet with the exhaust air duct (8) and the outdoor air supply duct (15). 5. A device according to claim 3 or 4, c h a r- a c t e r i z e d in that the outlet (9) of the fan (1) communicates by means of a damper (12) with an air removal duct (13) bypassing the gas flue (6) and leading to outdoor air, the damper (12) connecting selectively the fan outlet with the injector nozzle (10) and the air removal duct (13). 6. A device according to any of claims 3 to 5, c h a r a c t e r i z e d in that the fan (1) is a fireplace fan arranged to be mounted beside the gas flue (6) of a fireplace chimney (3). AMENDED CLAIMS [received by the International Bureau on 2 June 1992 (02.06.92); original claims 3 and 4 replaced by amended claim 3 new claims added; claims 5 and 6 unchanged but renumbered as claims 4 and 5 other claims unchanged (2 pages)] 1. A method of mechanically removing gas from a room space (4) , wherein - harmful gases are removed from the room space by sucking them through a gas flue (6) in which suction is created by an injection effect produced by a flow of air (A) passed from the side of the flue into the flue by means of a fan (1) ; and - exhaust air is removed from the room space by sucking it through an exhaust air duct (8) , c h a r a c t e r i z e d in that the air for the in¬ jection effect is passed into the flue (6) by means of the fan (1) selectively from the exhaust air duct (8) and/ or from outdoor air (15) . 2. A method according to claim 1, c h a r a c ¬ t e r i z e d in that part of the air from the exhaust air duct (8) is passed into outdoor air (13) before the gas flue (6) . 3. A device for removing gas from a room space (4) through a gas flue (6) , comprising a fan (1) mounted to the side of the gas flue and having an outlet (9) commu¬ nicating with an injector nozzle (10) projecting into the gas flue (6) and an inlet (7) communicating with a source of air (15) positioned exteriorly of the gas flue (6) to create a flow of air (A) which causes a suction effect in the gas flue, an exhaust air duct (8) being provided for the room space (4) for mechanical ventilation of the room space, c h a r a c t e r i z e d in that the inlet (7) of the fan (1) communicates with a supply duct (15) for outdoor air by means of a damper (14) which selectively connects the fan inlet with the exhaust air duct (S) for the room space (4) and the outdoor air supply duct (15) . 4. A device according to claim 3, c h a r a c ¬ t e r i z e d in that the outlet (9) of the fan (l) com- municates by means of a damper (12) with an air removal duct (13) bypassing the gas flue (6) and leading to out¬ door air, the damper (12) connecting selectively the fan outlet with the injector nozzle (10) and the air removal duct (13) . 5. A device according to claim 3 or 4, c h a r ¬ a c t e r i z e d in that the fan (1) is a fireplace fan arranged to be mounted beside the gas flue (6) of a fire¬ place chimney (3) . STATEMENTUNDERARTICLE19 Original pages 5 and 6 are replaced by new pages 5 and 6. Claims l and 2 remain unchanged. Claims 3 and 4 are replaced by amended claim 3 which is a combination of claims 3 and 4 as filed. Claims 5 and 6 remain unchanged except that these claims have been renumbered as 4 and 5 and have been amended to refer to claim 3 and claims 3 or 4, respectively.

Inventors: LAHTI KARI, SAREN JARI, SELIN MIKKO, LAHTI, KARI, SAREN, JARI, SELIN, MIKKO
Applicants: SUOMEN PUHALLINTEHDAS OY
Application year: 1991
Main classification: F24F7
IPC codes: F23L17, F24F7