GB1578398A - Heater arrangement - Google Patents

Description

t54) A HEATER ARRANGEMENT (71) We, JOH. VAILLANT KG, a German Company of 5630 Remscheid, Berghauser Strasse 40, Germany, 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 a heater arrangement.

It is known that heaters such as boilers, gas- or oil-heated water heaters or furnaces require a specific excess amount of air in order to obtain an optimal combustion. Such a heater is normally adjusted in such a manner that a specific fuel throughput to a burner is effected, having associated therewith a likewise constant air throughput. Accordingly, the relationship between both is constant and selected such that the excess amount of air is guaranteed at the nominal output of the appliance. However, this arrangement is not useful if the fuel throughput to the heater is continuously variable or adjusted in steps due to a capacity control of the beater. Since the air throughput is adjusted to maximum or also to nominal output of the appliance, too great excess amounts of air are operated within the partial-load region.

According to the present invention, there is provided a heater arrangement in which air is supplied to a closed heater including a burner adapted to be fed with a fluid fuel and having an air supply line, provided with a blower, in which there is arranged a main throttle valve and a measuring arrangement for the amount of air passing through said air supply line, wherein said measuring arrangement is bridged by an air bypass line in which a further throttle valve is arranged, and that both throttle valves are adjustable in the same sense in dependence on the pressure of the fluid fuel fed to said burner.

The invention will be more fully understood from the following description given by way of example only with reference to the single figure of the accompanying drawing which is a schematic diagram of a heater arrangement.

Referring now to the drawing a heater arrangement has a heater shown generally at 1 which has a closed interior 3 sealed in a fluid-tight manner by a sheet metal enclosure 2 at the place of installation. Interior 3 terminates an air supply line 5 provided with a blower 4 and a fuel supply line 8 leading to a burner 6 and provided with a solenoid valve 7. In the interior 3 above the burner 6 there is provided a heat exchanger 9 through which water tubes (not shown) pass, and to which is connected an exhaust line 10, so that hot gases produced by the burner 6 pass through heat exchanger 9 and exhaust through the said exhaust line 10 without being impeded.

Air supply line 5 has a constriction 11 which includes a measuring line 12 that terminates in said constriction and also a Pitot tube 13 the measuring line 14 of which together with the measuring line 12 lead to a differential pressure gauge 15 that is a limit value switch actuating an electric contact 16 connected in an electric line 17 leading to a field coil 18 of the solenoid valve 7. Connected in line 17 is a contact 19A of a thermostat 19, for use for example inside or outside of a room.

Connected in the air supply line 5 is a main butterfly type throttle valve 21 rotatable about a shaft 20 to control air supply shown by arrow 24. On the same shaft 20 is an auxiliary throttle valve 22 rotatably supported but in an air bypass-line 23 bridging both the main throttle valve 21 and the constriction 11.

A measuring line 25 that leads to an adjusting member 27 is provided with a diaphragm 26 that banches off from the air supply line 5.

A pressure chamber 28 on one side of the diaphragm 26 is connected with the interior of the burner 6 via a pressure line 29 and is able to measure the air pressure in said line towards the burner 6. Another pressure chamber 30 on the other side of the diaphragm 26 connects to the measuring line 25.

The adjusting member 27 rotates the main and auxiliary throttle valves 21, 22 against the restoring force of a helical spring 31 that forces both throttle valves 21, 22 into the closed position.

The modus operandi of the arrangement described above is as follows:- starting from the position of rest shown no differential pressure is applied to the differential pressure gauge 15, the contact 16 being open. Hence, the coil 18 of the solenoid valve 7 is not activated, and the solenoid valve 7 is closed. The burner is out and does not burn.

The blower also is in a position of rest. The diaphragm 26 is in the drawing at the left end position due to the action of the spring 31 and the main and auxiliary throttle valves 21 and 22 are closed the position of valve 21 being shown in dotted lines.

If heat is now demanded by the thermostat 19 the heater 1 is brought into operation, first the motor (not shown) of the blower 4 is caused to start. Thereby, a small air current 24A is passed to the heater since the two throttle valves 21, 22 are closed. However, this small air current is sufficient to build up a differential pressure at the constriction 11 so that the limit value adjusted at the differential pressure gauge 15 is exceeded. Thereby, the differential pressure gauge 15 closes contact 16 so that the solenoid valve 7 opens. Therewith, fuel is supplied to the burner 6 and ignited in a manner not shown. The pressure now present in the burner, of the fuel is passed to the adjusting member 27 causing an analogous deflection of the diaphragm 26 against the restoring force of the spring 31 to open both throttle valves 21 and 22.Hence, the air through the air supply line 5 is controlled in dependence on the pressure in the burner, that is indirectly in dependence on the burner capacity. If, due to less heat requirement the solenoid valve 7 closes a little and throttles the gas supply to the burner 6, the pressure in the burner will drop. Consequently, the spring 31 moves the throttle valves 21, 22 slightly into the direction of closing so that the reduced gas supply is followed by a reduced air supply 24. However, in both cases the air excess is equal. The bypass line 23 serves to maintain an additional air current which is not measured at the constriction 11.

In a modification of the arrangement described above the position of rest may be defined by the position of closure of only one throttle valve. In the maximum opening the position is defined by the parallel arrangement of the valves with respect to the tube wall.

WHAT WE CLAIM IS: 1. A heater arrangement in which air is supplied to a closed heater including a burner adapted to be fed with a fluid fuel and having an air supply line, provided with a blower, in which there is arranged a main throttle valve and a measuring arrangement for the amount of air passing through said air supply line, wherein said measuring arrangement is bridged by an air bypass line in which a further throttle valve is arranged, and that both throttle valves are adjustable in the same sense in dependence on the pressure of the fluid fuel fed to said burner.

2. The arrangement according to Claim 1, wherein the air bypass line bridges both the main throttle valve and also the measuring arrangement in the air supply line.

3. The arrangement according to Claims 1 or 2, wherein both throttle valves are adjustable in the same sense of rotation.

4. The arrangement according to any one of the Claims 1 to 3, wherein an adjusting member is adapted to sense the said pressure of fluid fuel to the burner relative to the pressure in the air supply line, and that a diaphragm adjusts the two throttle valves, supported on a single adjusting shaft, against the restoring force of a spring.

5. A heater arrangement constructed and arranged substantially as herein described and shown in the single figure of the accompanying drawing.

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

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. starting from the position of rest shown no differential pressure is applied to the differential pressure gauge 15, the contact 16 being open. Hence, the coil 18 of the solenoid valve 7 is not activated, and the solenoid valve 7 is closed. The burner is out and does not burn. The blower also is in a position of rest. The diaphragm 26 is in the drawing at the left end position due to the action of the spring 31 and the main and auxiliary throttle valves 21 and 22 are closed the position of valve 21 being shown in dotted lines. If heat is now demanded by the thermostat 19 the heater 1 is brought into operation, first the motor (not shown) of the blower 4 is caused to start. Thereby, a small air current 24A is passed to the heater since the two throttle valves 21, 22 are closed. However, this small air current is sufficient to build up a differential pressure at the constriction 11 so that the limit value adjusted at the differential pressure gauge 15 is exceeded. Thereby, the differential pressure gauge 15 closes contact 16 so that the solenoid valve 7 opens. Therewith, fuel is supplied to the burner 6 and ignited in a manner not shown. The pressure now present in the burner, of the fuel is passed to the adjusting member 27 causing an analogous deflection of the diaphragm 26 against the restoring force of the spring 31 to open both throttle valves 21 and 22.Hence, the air through the air supply line 5 is controlled in dependence on the pressure in the burner, that is indirectly in dependence on the burner capacity. If, due to less heat requirement the solenoid valve 7 closes a little and throttles the gas supply to the burner 6, the pressure in the burner will drop. Consequently, the spring 31 moves the throttle valves 21, 22 slightly into the direction of closing so that the reduced gas supply is followed by a reduced air supply 24. However, in both cases the air excess is equal. The bypass line 23 serves to maintain an additional air current which is not measured at the constriction 11. In a modification of the arrangement described above the position of rest may be defined by the position of closure of only one throttle valve. In the maximum opening the position is defined by the parallel arrangement of the valves with respect to the tube wall. WHAT WE CLAIM IS:

1. A heater arrangement in which air is supplied to a closed heater including a burner adapted to be fed with a fluid fuel and having an air supply line, provided with a blower, in which there is arranged a main throttle valve and a measuring arrangement for the amount of air passing through said air supply line, wherein said measuring arrangement is bridged by an air bypass line in which a further throttle valve is arranged, and that both throttle valves are adjustable in the same sense in dependence on the pressure of the fluid fuel fed to said burner.

2. The arrangement according to Claim 1, wherein the air bypass line bridges both the main throttle valve and also the measuring arrangement in the air supply line.

3. The arrangement according to Claims 1 or 2, wherein both throttle valves are adjustable in the same sense of rotation.

4. The arrangement according to any one of the Claims 1 to 3, wherein an adjusting member is adapted to sense the said pressure of fluid fuel to the burner relative to the pressure in the air supply line, and that a diaphragm adjusts the two throttle valves, supported on a single adjusting shaft, against the restoring force of a spring.

5. A heater arrangement constructed and arranged substantially as herein described and shown in the single figure of the accompanying drawing.