GB1603495A

GB1603495A - Incandescent gas fired space heaters

Info

Publication number: GB1603495A
Application number: GB371977A
Authority: GB
Original assignee: Valor Heating Ltd
Current assignee: Valor Heating Ltd
Priority date: 1978-04-26
Filing date: 1978-04-26
Publication date: 1981-11-25

Description

(54) IMPROVEMENTS IN iNCANDESCENT GAS FIRED SPACE HEATERS (71) We, VALOR HEATING LIMITED, a British Company of Wood Lane, Bromford, Erdington, Birmingham 24, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: This invention relates to improvements in incandescent gas fired space beaters of the kind comprising an outer casing housing therewithin at least one radiant arranged to be heated by a gas burner, the radiant forming part of a boundary of a combustion chamber provided with an outlet to a heat exchanger through which the products of combustion of the gas are circulated before being discharged to a flue and air circulated between the heat exchanger and the outer casing being heated by the combustion products flowing through the heat exchanger.

Such a heater will hereinafter be referred to as of the kind set forth.

A problem associated with space heaters of the kind set forth is that in use insufficient flue pull can result in spillage of the products of combustion into the space between the combustion chamber and the outer casing where they are mixed with the air circulating between the heat exchanger and the outer casing and are ultimately discharged into the room. This results in ct severe health hazard as the products of combustion in dude varying amounts of carbon monoxide which is poisonous and even in small amounts causes sickness. Flue pull is least and consequently the likelihood of spillage greatest when starting the fire.

The problem can substantially be relieved by increasing the flue pull. One way of increasing flue pull is to pass the excess combustion air through the heat exchanger together with the products d combustion.

However this is unsatisfactory as not only are the products of combustion drawn through the heat exchanger more rapidly but also the excess combustion air is considerably cooler than the products of combustion and therefore the heat vaiue of the latter is greatly reduced. Consequently the efficiency of the heat exchanger at any setting of the fire is considerably reduced. In addition the increase in the speed of discharge of the combustion products causes the fire to use more fuel, especially at any higher setting of the fire, but this increase is not matched by corresponding increase in overall heat output of the fire for the above reasons. Another way of increasing flue pull is to pass the excess combustion air through a separate air conduit extending between the inlet to the heat exchanger and the outlet from the heat exchanger to the flue.This is an improvement on the previous method in the the excess combustion air no longer exerts a cooling effect on the products of combustion and the effifficiency of the fire is thereby increased. A common feature of these known heat exchangers is that the products of combustion follow a single flow path through the heat exchanger. Consequently there tends to be a continual reduction in the temperature of the heat exchanger from the inlet to the outlet. As a result the maximum use of the available metal surface of the heat exchanger is not utilised in heating the convection air.

The terms upper and lower, front and rear, vertical etc. as used herein and in the appendant claims refer to the heater in its normal position of use as indicated in the accompanying drawings.

According to the present invention we provide an incandescent gas fired space heater of the kind set forth in which the heat exchanger is divided into two compartments by a dividing plate, one compartment having at least one inlet connected to the outlet from the combustion chamber and. the other compartment having an outlet adapted to be connected to the flue, and the dividing plate is provided with a plurality of openings through which the products of combustion can flow from said one compartment to said other compartment, said one inlet to said one compartment being so arranged and the openings being so arranged that the flow of combustion products entering said one compartment through said one inlet is split into a plurality of streams which flow in different directions, each generally parallel to the plane of the dividing plate, to said openings, and a separate conduit is arranged such that in the excess combination air is channelled through the conduit from the combustion chamber to the flue, and is kept separate from the products of combustion in said compartment.

The separate conduit increases the flue pull and prevents spillage of the products of combustion and, by appropriate choice of the size number and arrangement of the openings in the dividing plate the optimum operating conditions can be obtained.

Preferably the heat exchanger is substantially rectangular in section and the dividing plate is arranged to extend vertically within the heat exchanger dividing the latter into front and back compartments. The openings in the dividing plate are arranged at the upper and lower ends respectively of the dividing plate. Preferably two openings are provided at the upper end adjacent to the corners of the dividing plate while a single, centrally-located opening is provided at the lower end. It has been found that this arrangement of openings provide a stabilising draft over a wide range of flue pulls and the efficiency of the fire is substantially independent of changes in flue pull and the radiants tend to glow all the time giving a pleasing effect.This is a considerable improvement over the known heat exchangers where high flue pull causes a considerable reduction in efficiency.

Preferably the front compartment has two inlets each connected to a respective outlet from the combustion chamber.

It will be appreciated that by use of the dividing plate to divide the heat exchanger into two compartments the construction of the heat exchanger is greatly simplified with consequent reduction in the cost of production. Indeed far fewer joints between components are required as compared to the known heat exchangers. This of course also reduces the likelihood of any leaks occurring through faulty joints and improves the safety of the fire.

The invention will now be described by way of example only, with reference to the accompanying drawings in which : Figure I is a transverse section through an incandescent gas fired space heater provided with a heat exchanger having a dividing plate; and Figure 2 is a view of the heat exchanger along the line 1-1 of Figure 1.

The gas-fired space heater illustrated comprises a combustion chamber 1 a part of a boundary of which is formed by a number of radiants la in side-by-side relationship which are supported above a gas burner 2. The backs of the radiants rest against horizontal ribs 3, 4 which project forwardly from an upstanding rear wall 5 of the combustion chamber. A top wall 6 of the combustion chamber projects forwardly from the rear wall 5 and its front end is shaped to form a downwardly depcnding flange 7 having an inwardly directed lip 7a which abuts the upper front face of the radiants and retains the radiants in position. The rear face of the radiants and the rear and top walls, 5, 6 of the combustion chamber define an enclosure into which the products of combustion are discharged.Two eliptical outlets 8, 9 project rearwardly from the upper end of the rear wall 5.

An upstanding heat exchanger 10 is arranged behind the combustion chamber 1 and projects upwardly above the combustion chamber.

The heat exchanger is of sheet metal pressed construction, rectangular in section.

The height of the exchanger is considerably greater than its depth and the width is slightly less than the inside width of an outer louvred casing 11 of the fire which houses the combustion chamber 1 and heat exchanger 10. The heat exclanger is split into two compartments 12, 13 by a vertical dividing plate 14. Two elliptical inlets 15, 16 project forwardly from the front or first compartment 12 and each is connected to a respective one of the outlets 8 9 from the combustion chamber. A rectangular outlet 17 projects rearwardly from the rear or second compartment for connection to a suitable flue or other outlet. The dividing plate 14 is provided with three openings 18, 19, 20 through which products of combustion can flow from the first compartment 12 to the second compartment 13.The openings 18, 19 are at the end of the dividing plate adjacent to the corners while the opening 20 is centrally located at the lower end of the dividing plate. The area nf opening 20 is approximately equal to the combined area of openings 18, 19.

A conduit 21 having an inlet 22 adjacent to the upper end of the radiants extends rearwardly through an opening in the heat exchanger and terminates in an outlet 23 within the second compartment 13 of the heat exchanger. The conduit 21 channels excess combustion air from the radiants and discharges this air into the flue or other suitable outlet at the same pomt as the products of combustion are discharged.

As shown the casing 11 is substantially chair-shaped in cross section to accommodate the upper end of the heat exchanger which projects above the combustion chamber 1. The casing 11 has an inlet 24 for convection air at its lower end and a louvred outlet 25 for heated convection air at its upper end. Simulated fuel (not shown) for example an imitation log fire effect or the like is arranged on the casing above the combustion chamber 1 and in front of the upwardly projecting portion of the heat exchanger i.e. in the area A indicated in Figure 1.

Operation of the heater is as follows.

Combustion products entering the first compartment 12 through the inlets 15, 16 are generally split into three streams, two of which flow in directions generally parallel to the plane of the plate 14 towards the openings 18, 19 at the upper end of the dividing plate. The other stream flows in substantially the opposite direction towards the opening 20 at the lower end of the plate.

The combustion products pass through the openings 18, 19, 20 into the second compartment 13 and flow in three streams towards each other which meet at the outlet 17 and are discharged into the flue or other suitable outlet. Simultaneously excess combustion air is channelled through the conduit 21 and is discharged into the second compartment 13 adjacent to the outlet 17. Convection air entering the inlet 24 at the lower end of the casing passes upwards through the space between the casino 11 and the heat exchanger 10 where the air is heated by heat exchange with the combustion products before being discharged through the louvred outlet 25 at the upper end of the casing.

The excess combustion air augments the flue pull and ensures that the flue pull is usually sufficient to prevent spillage of the combustion products into the room. The construction of the heater in which the lip 7a of the depending flange 7 retains the radiants in position ensures that the combustion products are discharged into a closed enclosure so that any spillage which may occur will be slight. If any spillage occurs the combustion products are entrained with the excess combustion air passing through the conduit 21 thereby preventing leakage of the combustion products into the room.

The inlets 15, 16 to the front compartment and the openings 18, 19, 20 in the dividing plate are arranged so that the flow of combustion products results in uniform distribution of heat in the front compartment and the temperature is substantially the same throughout the compartment. Similarly the temperature is substantially the same throughout the rear compartment although there is a slight reduction in temperature as compared with the front compartment. The temperature gradient which exists in the heat exchanger therefore tends to be one between the front and rear comparts only. Far greater use is therefore made of the available metal surface of the heat exchanger to heat the convection air and the efficiency in the heating of the convection air is therefore greater as compared with known heat exchangers.The heat exchanger of the present invention can therefore be made quite shallow in depth and as a result is particularly adaptable for use in any number of fires with little or no modification of the design other than overall dimensions to suit the size of fire. The simple design of heat exchanger in which the external surface is substantially unbroken allows for easier and smoother flow of the convected air which increases the speed with which the air passes through the fire, reduces the turbulance associated with other more complicated designs of heat exchangers and therefore increases the efficiency.

Various modifications of the above construction are envisaged, for example the inlet and outlet connections between the front compartment of the heat exchanger and the combustion chamber and the openings in the dividing plate may be of any suitable configuration. Also the numbers and positions of the openings in the dividing plate may be varied as required to produce two streams of combustion products flowing in substantially opposite directioiis in the front compartment. Thus the dividing plate may have one opening at its upper end and one opening at its lower end. Furthermore the number of inlet and outlet connections between the front compartment of the heat exchanger and The combustion chamber may be varied as required, for example only one such connection may be provided.However the inlet and outlet connection(s) and the openings in the dividing plate are arranged so that a uniform distribution of heat is obtained in the front compartment.

Although in the above described embodiment the combustion chamber and heat exchanger are constructed and arranged to fit within a chair-shaped casing to allow the provision of a simulated fuel effect it will be understood that the combustion chamber and heat exchanger could be constructed and arranged to fit within different shapes of casing.

WHAT WE CLAIM IS: 1. An incandescent gas fired space heater of the kind set forth in which the heat exchanger is divided into two compartments by a dividing plate, one compartment having at least one inlet connected to the outlet from the combustion chamber and the other compartment having an outlet adapted to be connected to the flue, and the dividing plate is provided with a plurality of openings through which the products of combustion can flow from said one compartment to said other compartment, said one inlet to said

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. outlet 25 for heated convection air at its upper end. Simulated fuel (not shown) for example an imitation log fire effect or the like is arranged on the casing above the combustion chamber 1 and in front of the upwardly projecting portion of the heat exchanger i.e. in the area A indicated in Figure 1. Operation of the heater is as follows. Combustion products entering the first compartment 12 through the inlets 15, 16 are generally split into three streams, two of which flow in directions generally parallel to the plane of the plate 14 towards the openings 18, 19 at the upper end of the dividing plate. The other stream flows in substantially the opposite direction towards the opening 20 at the lower end of the plate. The combustion products pass through the openings 18, 19, 20 into the second compartment 13 and flow in three streams towards each other which meet at the outlet 17 and are discharged into the flue or other suitable outlet. Simultaneously excess combustion air is channelled through the conduit 21 and is discharged into the second compartment 13 adjacent to the outlet 17. Convection air entering the inlet 24 at the lower end of the casing passes upwards through the space between the casino 11 and the heat exchanger 10 where the air is heated by heat exchange with the combustion products before being discharged through the louvred outlet 25 at the upper end of the casing. The excess combustion air augments the flue pull and ensures that the flue pull is usually sufficient to prevent spillage of the combustion products into the room. The construction of the heater in which the lip 7a of the depending flange 7 retains the radiants in position ensures that the combustion products are discharged into a closed enclosure so that any spillage which may occur will be slight. If any spillage occurs the combustion products are entrained with the excess combustion air passing through the conduit 21 thereby preventing leakage of the combustion products into the room. The inlets 15, 16 to the front compartment and the openings 18, 19, 20 in the dividing plate are arranged so that the flow of combustion products results in uniform distribution of heat in the front compartment and the temperature is substantially the same throughout the compartment. Similarly the temperature is substantially the same throughout the rear compartment although there is a slight reduction in temperature as compared with the front compartment. The temperature gradient which exists in the heat exchanger therefore tends to be one between the front and rear comparts only. Far greater use is therefore made of the available metal surface of the heat exchanger to heat the convection air and the efficiency in the heating of the convection air is therefore greater as compared with known heat exchangers.The heat exchanger of the present invention can therefore be made quite shallow in depth and as a result is particularly adaptable for use in any number of fires with little or no modification of the design other than overall dimensions to suit the size of fire. The simple design of heat exchanger in which the external surface is substantially unbroken allows for easier and smoother flow of the convected air which increases the speed with which the air passes through the fire, reduces the turbulance associated with other more complicated designs of heat exchangers and therefore increases the efficiency. Various modifications of the above construction are envisaged, for example the inlet and outlet connections between the front compartment of the heat exchanger and the combustion chamber and the openings in the dividing plate may be of any suitable configuration. Also the numbers and positions of the openings in the dividing plate may be varied as required to produce two streams of combustion products flowing in substantially opposite directioiis in the front compartment. Thus the dividing plate may have one opening at its upper end and one opening at its lower end. Furthermore the number of inlet and outlet connections between the front compartment of the heat exchanger and The combustion chamber may be varied as required, for example only one such connection may be provided.However the inlet and outlet connection(s) and the openings in the dividing plate are arranged so that a uniform distribution of heat is obtained in the front compartment. Although in the above described embodiment the combustion chamber and heat exchanger are constructed and arranged to fit within a chair-shaped casing to allow the provision of a simulated fuel effect it will be understood that the combustion chamber and heat exchanger could be constructed and arranged to fit within different shapes of casing. WHAT WE CLAIM IS:

1. An incandescent gas fired space heater of the kind set forth in which the heat exchanger is divided into two compartments by a dividing plate, one compartment having at least one inlet connected to the outlet from the combustion chamber and the other compartment having an outlet adapted to be connected to the flue, and the dividing plate is provided with a plurality of openings through which the products of combustion can flow from said one compartment to said other compartment, said one inlet to said

one compartment being so arranged and the openings being so arranged that the flow of combustion products entering said one compartment through said one inlet is split into a plurality of streams which flow in different directions, each generally parallel to the plane of the dividing plate to said openings, and a separate conduit is arranged such that in the excess combination air is channelled through the conduit from the combustion chamber to the flue, and is kept separate from the product of combustion in said one compartment.

2. A heater according to claim 1 in which the dividing plate extends substantially vertically within the heat exchanger.

3. A heater according to claim 2 in which the openings in the dividing plate are arranged at the upper and lower ends of the dividing plate.

4. A heater according to claim 3 in which the dividing plate is substantially rectangular and has two openings at the upper end adjacent to the corners of the dividing plate and a further centrally-located opening at the lower end.

5. A heater according to claim 4 in which the area of the centrally-located lower opening is substantially the same as the combined area of the two upper openings.

6. A heater according to any one of claims 1 to 5 in which said one compartment has two inlets each connected to a respective outlet from the combustion chamber.

7. A heater according to any one of the preceding claims in which the conduit has an inlet adjacent to the upper end of the radiants and extends rearwardly through an opening in the heat exchanger to an outlet within said other compartment.

8. A heater according to any one of the preceding claims in which the heat exchanger projects above the combustion chamber.

9. A heater according to claim 8 in which the outer casing is of generally chair shape enclosing the heat exchanger and the combustion chamber and a simulated fuel is accommodated on the outer casing above the combustion chamber and in front of the portion of the heat exchanger projecting above the combustion chamber.

10. An incandescent gas fired space heater of the kind set forth substantially as herein described with reference to the accompanying drawings.