AT391203B - WATER SWITCH FOR A WATER HEATER - Google Patents

Description

No. 391 203

The invention relates to a water switch for a water heater, which controls the fuel supply to a burner and is arranged in the water supply line as a function of a pressure difference in the two chambers of a housing divided by a membrane that occurs during water flow and is generated by a Venturi tube and at the narrow point of which the chamber pressurized with the lower pressure is connected via a connecting line, the chamber of the water switch, which is pressurized with a lower water pressure, being assigned at least one connecting pipe with at least one valve for controlling the emptying or filling speed of this chamber.

Such a water switch is known from DE-OS 2 134 048. In such water switches, it is known that after opening a nozzle the pressure in one chamber drops in relation to the pressure prevailing in the other chamber, and the chamber under the lower pressure becomes thereby at least partially emptied. Conversely, when the nozzle is closed, this chamber must be filled with water again as quickly as possible in order to have the switch stop the fuel supply to the burner.

The greater the pressure in the supply line, the greater the pressure difference that occurs when tapping and the faster the chamber is emptied when the nozzle is opened.

This emptying and the resulting presentation of the membrane and the fuel supply valve must not take place too quickly, however, in order to ensure that the burner is properly ignited. On the other hand, the chamber should fill as quickly as possible when the dispensing process is completed in order to end the unnecessary fuel supply to the burner as soon as possible.

The object of the invention is to accelerate the filling process of the chamber.

This object is achieved in a water switch according to the invention in that a branch line bypassing the connecting line is provided, in which a check valve is provided.

This parallel connection of the check valve with the control valve has the advantage that it can support the control valve in the closing movement of the gas valve particularly easily.

An embodiment of a water switch of a water heater according to the invention is illustrated schematically in the single drawing figure.

This water switch (1) consists of a housing (2), in which a membrane (3) is clamped, which carries a membrane plate (4) and divides the housing (2) into the chambers (5) and (6). The membrane plate (4) has an actuator (7) for controlling a control and regulating valve, not shown, arranged in the fuel supply line to the burner of the water heater.

The chamber (5) of the water switch (1) is supplied with water from a water supply line (8) and it flows via the feed line (9) to a heat exchanger (not shown) of the water heater. A venturi tube (10) is provided in this inlet line (9), behind the constriction (11) of which the chamber (5) is suppressed when flowing through, and is transmitted to the interior of the chamber (6) via the connecting line (12) and gives the pressure difference that can be used to control the valve of the fuel supply line

When a dispensing valve arranged in the tap line of the heat exchanger is opened and a water throughput caused thereby in the supply line (8), the chamber (5) of the water switch (1) and the inlet line (9) with the venturi tube (10) is accordingly reduced Pressure in the chamber (6) so that the diaphragm (3), the diaphragm plate (4) and the actuator (7) are caused to move upwards, with which the actuator (7) at least partially opens the gas supply valve. For this upward movement, the chamber (6) must at least partially empty itself.

In order to target the speed of this emptying, d. H. delaying influence, an adjustable control valve (13) is arranged in the connecting line (12) between the chamber (6) and the inlet line (9). So if the water pressure in the supply line (8) is too high and accordingly the speed of the emptying is too high, this speed can be reduced by throttling the water flow in the connecting line (12) so that a proper ignition of the burner during the emptying phase is guaranteed

When closing the pintle valve, on the other hand, it is important that the emptied chamber (6) fills again as soon as possible so that the actuator (7) quickly stops the gas supply to the burner. The inflow of the water filling the chamber is mainly used by the branch line from the connecting line (12) Branch line (14), in which, according to the invention, there is a check valve (15) which, although it allows the inflow of water, prevents the escape from the chamber (6). The escaping water is rather forced to take the path via the control valve (13). If the branch line is of sufficient size, filling the chamber (6) only requires an optimally short period of time.

The diagram shown in the drawing also shows a control piston (18) movable in the guide (16) and pressed by a compression spring (17) onto the underside of the membrane (3) to keep the water flow constant.

Furthermore, a control piston (19) is provided with a partly cylindrical, partly conical body, which is equally influenced by a compression spring (20) supported against the housing (2), bears against the diaphragm (3) and is moved by it. This control piston (19) is arranged in the inlet of a bypass line (21) which starts from the chamber (5) and opens into the feed line (9) to the heat exchanger. It is the positive feedback piston which, depending on the stroke, releases a quantity of water to the heat exchanger parallel to the Venturi tube (10). -2-

Claims (5)

No. 391 203 Finally, a temperature selector (23) is provided in a further bypass line (22), the valve body (24) of which interacts with a valve seat (25). With this temperature selector (23), the amount of water flowing through the heat exchanger can be increased. With the same amount of fuel, the outlet temperature of the water is reduced. 1. Water switch for a water heater which controls the fuel supply to a burner and is arranged in the water supply line as a function of a pressure difference in the two chambers of a housing divided by a membrane and is arranged in the water supply line, characterized in that with a water throughput Chamber (16) of the water switch (1) which is subjected to a lower pressure is assigned at least one connecting line (12) with at least one valve (13) or (15) for controlling the emptying or filling speed of this chamber (16) 2. Water heater according to claim 1 with a generation of a pressure difference in a water throughput in the two chambers of the water switch serving Venturi tube, at the constriction of which the chamber pressurized with the lower pressure is connected via a connecting line, characterized in that the control valve (13 ) is arranged in this connecting line (12). 3. Water heater according to claim 1 or 2, characterized in that the valve for controlling the speed of the filling is a check valve (15). 4. Water heater according to claim 3, characterized in that the check valve (15) in a chamber (6) with the inlet line (9) to the heat exchanger connecting line (12) is arranged. 5. Water heater according to claim 4, characterized in that the check valve (15) in a the control valve (13) bypassing branch line (14) of the connecting line (12) is arranged Hiezu 1 sheet drawing -3-