GB1599879A

GB1599879A - Gas-fired water heaters

Info

Publication number: GB1599879A
Application number: GB29413/77A
Authority: GB
Original assignee: TI Domestic Appliances Ltd
Current assignee: TI Domestic Appliances Ltd
Priority date: 1978-05-26
Filing date: 1978-05-26
Publication date: 1981-10-07

Description

(54) IMPROVEMENTS IN AND RELATING TO GAS-FIRED WATER HEATERS (71) We, T. I. DOMESTIC APPLI ANCES LIMITED, a British Company, of Radiation House, North Circular Road, London, NOW10 OJP, 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 gas-fired water heaters and has particular reference to gasfired water heaters for domestic use.

In such water heaters it has been common practice to employ pressure differences created by water flow through the heater to open a gas valve permitting gas flow to the main burner of the heater on commencement of water flow and to close the gas valve when water flow ceases. In some cases, the pressure difference is obtained by means of a venturi tube traversed by the water flow or a part thereof.

The pressure differences are applied to a flexible diaphragm which is coupled to the gas valve. The gas valve is spring loaded to ensure that maximum opening is not achieved until the water flow has reached a desired value. The spring loading is pre-set during manufacture and the arrangement is such that the loading cannot be adjusted by a user thereafter. Re-setting of the spring loading requires part of the control unit to be dismantled to give access to the spring and this requires the attention of a service engineer.

To give a user some control over the temperature rise imparted to water during its passage through the heater, it is known to fit the venturi with a by-pass passage containing a user-operated flow control valve. Opening the valve increases the water flow through the heater and this produces a decrease in the temperature of the water leaving the heater because there is no increase in gas flow to the main burner whose heat output thus remains constant. The addition of- the. by-pass passage and flow control valve complicates the construction of the control unit and increases its cost.

It is an object of the present invention to provide a control unit for a gas-fired water heater that is of simpler construction than hitherto and which nevertheless has facilities giving a user some degree of control over outlet water temperature.

According to the present invention, a gasfired water heater comprises a control unit including a water flow passageway having an inlet and an outlet, means responsive to water flow through the passageway for producing movement of a control member in accordance with the rate of water flow, a gas flow passageway having an inlet and an outlet, a gas flow control valve in the gas passageway, the gas flow control valve being linked to the member for movement therewith to control gas flow through the gas passageway, resilient means for resiliently loading the gas valve to permit movement thereof only when the water flow exceeds a predetermined value, and a user operated control for adjusting the resilient loading.

In one embodiment of the invention, the gas passageway has an outlet downstream in the direction of gas flow of the gas flow control valve for connection to a main gas burner and an aperture in which is mounted an adjustor for varying the resilient loading of the gas valve. The adjustor may be linked to an operating knob located externally of the casing of the water heater.

The control member may comprise a flexible disc-like diaphragm adapted to flex in response to the pressure difference set up between the mouth and throat of a venturi tube forming part of the water flow passageway. The diaphragm is linked by a connecting rod to the gas flow control valve.

In an embodiment of the construction just referred to, the diaphragm is mounted in a vertical plane, the connecting rod being horizontal, the outlet for connection to the main gas burner being upwardly facing to permit a main gas burner to be positioned above the control unit. This allows the aperture to be so positioned that it is easily accessible.

By way of example only, an embodiment of the invention will now be described in greater detail with reference to the accompany ing drawing which is a cross-section showing the embodiment in diagrammatic form only.

The water heater is basically of conventional form and has a control unit with a water section 1 and a gas section 2. The water section 1 has an inlet 3 leading to a passage 4, the flow through which is controlled by a water governor valve 5 linked to a disc-like flexible diaphragm 6 which divides an internal chamber into two parts one 7 of which is joined to the passage 4. The diaphragm 6 is mounted in a vertical plane.

Water leaving the first part 7 of the internal chamber then flows through a venturi-tube 8 and thence to the heat exchanger of the water heater via a water exit 9. The other part 10 of the internal chamber is connected to the throat of the venturi tube 8 and in this way the diaphragm is exposed to the pressure difference between the mouth and throat of the venturi.

The water governor valve 5 is linked for movement with the diaphragm by means of a connecting rod 11 and operates, as the diaphragm flexes under changing pressure differences, to ensure a constant water flow rate through the heater.

In contact with one of the faces of the diaphragm 6 is another connecting rod 12 linking the diaphragm 6 to a gas flow control valve 13 located in a gas flow passageway in the gas section 2. The gas section 2 is positioned alongside the water section 1 with the connecting rod 12 horizontal. Gas enters the gas section via inlet 14. Downstream of the gas flow control valve 13 in the direction of gas flow is a passageway 15 leading to the main gas burner (not shown) of the heater. In a horizontally extending branch 16 of inlet 14 is located an adjustor 17 for varying the loading of a spring 18 located in the branch 16 and acting on the gas valve 13 in the conventional manner.

The adjustor is connected to an actuating rod 19 which passes in gas-tight manner through the end wall of the branch 16 and is joined to a lever 20, movement of which by a user varies the spring loading.

Variation of the spring loading alters the pressure difference required to produce sufficient flexure of the diaphragm to open the gas valve to permit gas flow to the main burner and hence the temperature of water leaving the heater.

In this way, limited control of water temperature is provided without the complication of a bg-pass passage for the venturi and an associated water flow control Valve in the passage.

It will be appreciated that other means may be used to vary the spring loading of the gas valve. The rod 19 may be actuated by a cam mechanism or through gears.

The control unit may be associated with a heat exchanger of any conventional form to form the water heater. Water leaving the water exit 9 of the venturi flows through the heat exchanger part of which may be located round a combustion chamber.

The water heater may be a so-called instantaneous water heater or it may be a water heater unit forming part of a central heating unit.

WHAT WE CLAIM IS: 1. A gas-fired water heater comprising a control unit including a water flow passageway having an inlet and an outlet, means responsive to water flow through the passageway for producing movement of a control member in accordance with the rate of water flow, a gas flow passageway having an inlet and an outlet, a gas flow control valve in the gas passageway, the gas valve being linked to the member for movement therewith to control gas flow through the gas passageway, resilient means for resiliently loading the gas valve, and a user operated control for adjusting the resilient loading.

2. A water heater as claimed in claim 1 in which the gas passageway has an outlet downstream, in the direction of gas flow, of the gas flow control valve for connection to a main gas burner, and, adjacent the gas flow control valve, an aperture in which is mounted an adjustor for varying the resilient loading of the gas valve.

3. A water heater as claimed in a claim 2 in which the aperture is in the wall of a housing in which the resilient means is accommodated.

4. A water heater as claimed in claim 3 in which the housing comprises a further passage way in communication with respect the gas passage- way on the upstream side, with respect to gas flow through the passageway, of the gas flow control valve.

5. A water heater as claimed in claim 4 in which the resilient means comprises a coil spring located in the further passageway.

6. A water heater as claimed in claim 4 or 5 in which the gas passageway includes a portion which, when the unit is installed, is substantially vertical, and in which the further passageway extends sideways with respect to that portion.

7. A gas fired water heater substantially as herein described with reference to and as illustrated by the accompanying drawing.

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

Claims

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

ing drawing which is a cross-section showing the embodiment in diagrammatic form only.

The water heater is basically of conventional form and has a control unit with a water section 1 and a gas section 2. The water section 1 has an inlet 3 leading to a passage 4, the flow through which is controlled by a water governor valve 5 linked to a disc-like flexible diaphragm 6 which divides an internal chamber into two parts one 7 of which is joined to the passage 4. The diaphragm 6 is mounted in a vertical plane.

Water leaving the first part 7 of the internal chamber then flows through a venturi-tube 8 and thence to the heat exchanger of the water heater via a water exit 9. The other part 10 of the internal chamber is connected to the throat of the venturi tube 8 and in this way the diaphragm is exposed to the pressure difference between the mouth and throat of the venturi.

The water governor valve 5 is linked for movement with the diaphragm by means of a connecting rod 11 and operates, as the diaphragm flexes under changing pressure differences, to ensure a constant water flow rate through the heater.

In contact with one of the faces of the diaphragm 6 is another connecting rod 12 linking the diaphragm 6 to a gas flow control valve 13 located in a gas flow passageway in the gas section 2. The gas section 2 is positioned alongside the water section 1 with the connecting rod 12 horizontal. Gas enters the gas section via inlet 14. Downstream of the gas flow control valve 13 in the direction of gas flow is a passageway 15 leading to the main gas burner (not shown) of the heater. In a horizontally extending branch 16 of inlet 14 is located an adjustor 17 for varying the loading of a spring 18 located in the branch

16 and acting on the gas valve 13 in the conventional manner.

The adjustor is connected to an actuating rod 19 which passes in gas-tight manner through the end wall of the branch 16 and is joined to a lever 20, movement of which by a user varies the spring loading.

Variation of the spring loading alters the pressure difference required to produce sufficient flexure of the diaphragm to open the gas valve to permit gas flow to the main burner and hence the temperature of water leaving the heater.

In this way, limited control of water temperature is provided without the complication of a bg-pass passage for the venturi and an associated water flow control Valve in the passage.

It will be appreciated that other means may be used to vary the spring loading of the gas valve. The rod 19 may be actuated by a cam mechanism or through gears.

The control unit may be associated with a heat exchanger of any conventional form to form the water heater. Water leaving the water exit 9 of the venturi flows through the heat exchanger part of which may be located round a combustion chamber.

The water heater may be a so-called instantaneous water heater or it may be a water heater unit forming part of a central heating unit.

WHAT WE CLAIM IS: 1. A gas-fired water heater comprising a control unit including a water flow passageway having an inlet and an outlet, means responsive to water flow through the passageway for producing movement of a control member in accordance with the rate of water flow, a gas flow passageway having an inlet and an outlet, a gas flow control valve in the gas passageway, the gas valve being linked to the member for movement therewith to control gas flow through the gas passageway, resilient means for resiliently loading the gas valve, and a user operated control for adjusting the resilient loading.
2. A water heater as claimed in claim 1 in which the gas passageway has an outlet downstream, in the direction of gas flow, of the gas flow control valve for connection to a main gas burner, and, adjacent the gas flow control valve, an aperture in which is mounted an adjustor for varying the resilient loading of the gas valve.
3. A water heater as claimed in a claim 2 in which the aperture is in the wall of a housing in which the resilient means is accommodated.
4. A water heater as claimed in claim 3 in which the housing comprises a further passage way in communication with respect the gas passage- way on the upstream side, with respect to gas flow through the passageway, of the gas flow control valve.
5. A water heater as claimed in claim 4 in which the resilient means comprises a coil spring located in the further passageway.
6. A water heater as claimed in claim 4 or 5 in which the gas passageway includes a portion which, when the unit is installed, is substantially vertical, and in which the further passageway extends sideways with respect to that portion.
7. A gas fired water heater substantially as herein described with reference to and as illustrated by the accompanying drawing.