GB2184224A - Gas-fired heating appliance - Google Patents

Abstract

A gas heater has a horizontally extended flue 15 which allows the heater to be mounted remote from an outside wall. In order to drive the exhaust gases along the extra length of flue, the heater has a combustion air fan (14) which has an electric motor (16) driving two rotors (18, 19) mounted side-by-side. Air pressurized by a first rotor (19) is delivered to the centre of rotor (18) for further pressurization. The air passes to a gas burner 11, through a combustion chamber 12, and out through an elongated flue 15. <IMAGE>

Description

SPECIFICATION Gas-fired heating appliance This invention relates to a gas-fired heating appliance of the kind having a combustion fan delivering pressurized airto a burner.

The invention provides a gas-fired heating appliance having a burner and a long horizontal exhaust tube for its exhaust products, and a combustion fan adapted to deliver airfrom the space in which the appliance is located to the burner,the combustion fan comprising two centrifugal rotors mounted side-by-side to operate in series.

The rotors may be mounted on a common shaft driven by a single motor, with guide plate means directing the output from a first rotor to the input of the second rotor.

The combustion airfan provides the pressure required to drive the exhaust gases along the long horizontal exhaust tube without an unacceptable increase in overall size. The space available within the housing ofa gas-heating appliance is limited. By increasing only the width of the fan it is found possible to fit the fan into the required space. No separate exhaust fan is then required.

A long exhaust tube is defined as morethan one metre long, and may be as much as four metres long with two 900 bends.

A specific example of the invention is shown in the accompanying drawings, in which:- Figure lisa diagrammatic side view of a gas heating appliance incorporating a combustion air fan, Figure2 is a side sectional view of the fan of Figure 1, Figure3 is a front view ofthefan of Figure 1,and Figure 4 is a sectional view of the same fan in the direction of arrow IV of Figure 2.

Referring firstto Figure 1, a gas heating appliance has a gas burner (11) in a combustion chamber (12), a convention airfan (13)directing room airfrom the front ofthe appliance to be heated and to return into the room being heated. Acombustion airfan (14) of the centrifugal type takes in room air th roug h the rear of the appliance and directs it into the combustion chamber. Exhaust products leave the appliance through an exhaust tube (15). The exhaust tube leaves the appliance horizontally and may extend uptofour metres before terminating in an open space. The exhaust tube may also have two 900 bends in it. Thus the appliance may be mounted in positions distant from an outside wall or flue.

The combustion fan (14) pressurizes the exhaust products which by this means are driven along the exhaust tu be. When the exhaust tu be is relatively long, i.e. more than one metre long, but less than four metres, the pressure produced by the usual combustion fan must be increased to overcome the increased resistance as well as any back pressure due to wind conditions, although the through flow need not be increased.

As seen in Figures 2 and 4, the combustion fan (14) comprises a single electric motor (16) driving a shaft (17). Two identical centrifugal rotors (18,19) are mounted side-by-side on shaft (17), with a gap therebetween. A division plate (21 ) lies beside the first rotor(19), directing the driven airto pass through an annular opening around the circu mference of the plate.A wal I (20) beside and spaced from the division plate has a central opening through which air is directed to the centre ofthe second rotor(18). Thus, as shown by the arrows in Figure 4, air is drawn in through the rearofthe appliance, into the centre of rotor (19), forced radially out from the rotor, directed to the centre of the second rotor (18), and forced out radially from that rotorto exit through a flange (23) secured to the combustion chamber.

The two rotors are arranged in series so thatthe pressurized air from one is further pressurized in the other. The final pressure is not, of course, twice the pressure from the first, but is sufficient to increase the pressurefrom that required for a normal short flue, e.g. a balanced flue of 0.20-0.80 metres length to that requiredfora long flue, e.g. 1 metres long.

The space required for the fan is only increased by the width of a rotor casing, the same motor driving both rotors.

1. Agas-fired heating appliance having a burner and a long, normally substantially horizontal exhaust tu be for its exhaust products and a combustion airfan located to deliver room airto the burner, the combustion fan comprising two centrifugal rotors mounted side-by-side to operate in series in the airflow.

2. A heating appliance as claimed in claim 1, wherein said rotors are mounted on a common shaft driven by a single motor.

3. A heating appliance as claimed in claim 1 or claim 2,wherein there is guide meansfordirecting compressed air from the outer circumference of a first one of said rotors to the centre of a second one of said rotors.

4. A heating appliance as claimed in any of claims 1 to 3, having an air inlet in its rear surface.

5. A heating appliance as claimed in any of claims to4, having aconvectionairfanfordirecting room air to be heated in the heater and returned into the room.

6. A heating appliance as claimed in any of claims 1 to 5, wherein the two rotors are identical.

7. A gas-fired heating appliance substantially as described hereinbeforewith reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Gas-fired heating appliance This invention relates to a gas-fired heating appliance of the kind having a combustion fan delivering pressurized airto a burner. The invention provides a gas-fired heating appliance having a burner and a long horizontal exhaust tube for its exhaust products, and a combustion fan adapted to deliver airfrom the space in which the appliance is located to the burner,the combustion fan comprising two centrifugal rotors mounted side-by-side to operate in series. The rotors may be mounted on a common shaft driven by a single motor, with guide plate means directing the output from a first rotor to the input of the second rotor. The combustion airfan provides the pressure required to drive the exhaust gases along the long horizontal exhaust tube without an unacceptable increase in overall size. The space available within the housing ofa gas-heating appliance is limited. By increasing only the width of the fan it is found possible to fit the fan into the required space. No separate exhaust fan is then required. A long exhaust tube is defined as morethan one metre long, and may be as much as four metres long with two 900 bends. A specific example of the invention is shown in the accompanying drawings, in which:- Figure lisa diagrammatic side view of a gas heating appliance incorporating a combustion air fan, Figure2 is a side sectional view of the fan of Figure 1, Figure3 is a front view ofthefan of Figure 1,and Figure 4 is a sectional view of the same fan in the direction of arrow IV of Figure 2. Referring firstto Figure 1, a gas heating appliance has a gas burner (11) in a combustion chamber (12), a convention airfan (13)directing room airfrom the front ofthe appliance to be heated and to return into the room being heated. Acombustion airfan (14) of the centrifugal type takes in room air th roug h the rear of the appliance and directs it into the combustion chamber. Exhaust products leave the appliance through an exhaust tube (15). The exhaust tube leaves the appliance horizontally and may extend uptofour metres before terminating in an open space. The exhaust tube may also have two 900 bends in it. Thus the appliance may be mounted in positions distant from an outside wall or flue. The combustion fan (14) pressurizes the exhaust products which by this means are driven along the exhaust tu be. When the exhaust tu be is relatively long, i.e. more than one metre long, but less than four metres, the pressure produced by the usual combustion fan must be increased to overcome the increased resistance as well as any back pressure due to wind conditions, although the through flow need not be increased. As seen in Figures 2 and 4, the combustion fan (14) comprises a single electric motor (16) driving a shaft (17). Two identical centrifugal rotors (18,19) are mounted side-by-side on shaft (17), with a gap therebetween. A division plate (21 ) lies beside the first rotor(19), directing the driven airto pass through an annular opening around the circu mference of the plate.A wal I (20) beside and spaced from the division plate has a central opening through which air is directed to the centre ofthe second rotor(18). Thus, as shown by the arrows in Figure 4, air is drawn in through the rearofthe appliance, into the centre of rotor (19), forced radially out from the rotor, directed to the centre of the second rotor (18), and forced out radially from that rotorto exit through a flange (23) secured to the combustion chamber. The two rotors are arranged in series so thatthe pressurized air from one is further pressurized in the other. The final pressure is not, of course, twice the pressure from the first, but is sufficient to increase the pressurefrom that required for a normal short flue, e.g. a balanced flue of 0.20-0.80 metres length to that requiredfora long flue, e.g. 1 metres long. The space required for the fan is only increased by the width of a rotor casing, the same motor driving both rotors. CLAIMS

1. Agas-fired heating appliance having a burner and a long, normally substantially horizontal exhaust tu be for its exhaust products and a combustion airfan located to deliver room airto the burner, the combustion fan comprising two centrifugal rotors mounted side-by-side to operate in series in the airflow.

2. A heating appliance as claimed in claim 1, wherein said rotors are mounted on a common shaft driven by a single motor.

3. A heating appliance as claimed in claim 1 or claim 2,wherein there is guide meansfordirecting compressed air from the outer circumference of a first one of said rotors to the centre of a second one of said rotors.

4. A heating appliance as claimed in any of claims 1 to 3, having an air inlet in its rear surface.

5. A heating appliance as claimed in any of claims to4, having aconvectionairfanfordirecting room air to be heated in the heater and returned into the room.

6. A heating appliance as claimed in any of claims 1 to 5, wherein the two rotors are identical.

7. A gas-fired heating appliance substantially as described hereinbeforewith reference to the accompanying drawings.