DE2301832A1 - CONTROL DEVICE FOR A CENTRAL HEATING SYSTEM - Google Patents

Description

PATENT LAWYERS

DR.-ING. RICHARD GLAWE DIPL-ING. KLAUS DELFS DIPL-PHYS. DR. WALTER MOLL Monks Hamburg monks

8M0NCHEN26 2HAMBUIGSi

PO Box 37 WAITZSTR. 12th UEBHERRSTR. 20 TEL, (0411) W 22

Part. (0 * 11) 22 65 48 TEEX 2t 29 21 »ρ« TELEX 52 25 OS ip «

MDNCHEN

A. 3.1 /. iipparatenfabriek hY Wijmegen / Netherlands

Control device for a central heating system

ITEMS YOUR MESSAGE FROM OUR SIGN A. 15th REGARDS:

The invention relates to a control device for a central heating system with a heat generator, a circulation pump, an associated heat exchanger for the heating medium, supply lines for supplying the heating medium from the heat exchanger to space heaters and a flow heat exchanger for domestic water, furthermore with a three-way valve, which directs the heating medium either to the room radiators or to the flow heat exchanger, a boiler thermostat and a domestic water thermostat in the continuous heat exchanger, The three-way valve is switched by this thermostat at a given temperature in such a way that the heating

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diurn runs through the flow heat exchanger, una with one other temperature is switched so that the heating medium runs through the space heater.

In such control devices, the thermostat must for domestic or commercial water, if necessary together with a differential pressure switch in the continuous flow heat exchanger with service water supplying the temperature of the heating medium in the continuous heat meter Maintain a desired value so that the temperature of the domestic water fluctuates as little as possible. This thermostat Not only can the three-way valve be in the position leading to the heat exchanger at a given minimum temperature open, but it can also, if desired, be set up so that the heat generator and the circulation pump at Can be switched on as required. As soon as a specified waximal temperature is reached, the three-way valve must be switched back to the position supplying the space heater, while the heat generator and the circulation pump can be switched off again.

Since the sensor of the domestic water thermostat is usually inserted in the line for the heating medium in the flow heat exchanger, such a thermostat only responds very slowly to temperature differences in the domestic water. hrsb if at least the heating medium is in the immediate vicinity of the K; h- Ie ν 3 die-π ο π Thermos asked the shutdown; tempera bur for the TL · - '.

:) fj ^f i '*? η / η 4 '-

When mcstateii reaches hr.t, the three-way valve is opened to the position leading to the lumbar radiators. At this point in time, however, practically the entire volume of the heating medium contained in the heat exchanger has assumed a temperature corresponding to or even a higher temperature than the aforementioned switch-off temperature. In this case, a relatively large amount of hot water, the temperature of which is constantly decreasing, must run through the 3Xirchlauf heat exchanger before the hot water thermostat switches on again in order to cause the hot water to reach a low end temperature again. As a result, the temperature of the domestic water shows considerable fluctuations, in particular when the water is drawn off at a moderate rate at which the differential pressure valve is not yet actuated, or when such a differential pressure valve is not provided.

The temporal fluctuations are even more pronounced in the Winter operation when both the central heating and the Through-flow heat exchangers are used, as in this case the three-way valve is used after the domestic hot water thermostat has been switched off in the position that supplies the room heating elements is opened and the pump remains in operation, with the result that relatively hot water from the generator to the Hardly any radiators flows, while the heat generator (the one to can be switched off at this point, as the space radiators do not require any heat Heat generator through an indoor or outdoor thermostat

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can be effected) cold return water from the space heaters receives. As soon as the domestic hot water thermostat switches on again when the minimum temperature is reached, this will be The three-way valve is opened again in the position supplying the flow heat exchanger, whereupon it is relatively cold Water will initially cool the once-through heat exchanger by a certain amount.

The heating medium can be used in the heat exchanger belonging to the heat generator, and thus also in the flow heat exchanger, Reach a considerably high temperature, since the sensor of the boiler thermostat is generally behind in the heating medium the porridge-way valve in the one leading to the room radiators Line is arranged and since the sensor of the domestic water thermostat is at a relatively large distance from the heat generator «As soon as the three-way valve is in the position supplying the once-through heat exchanger through the, The domestic hot water thermostat is opened, the boiler thermostat out of operation, because it is no longer flushed with directly heated heating medium, or it is switched off in some other way, so that as a result the maximum temperature of the heating medium is no longer limited by the boiler thermostat. Another disadvantage is that the heat exchanger for the heating medium is constantly subjected to high thermal loads is.

This wake part of the considerable temperature fluctuations

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of the domestic water can be partially eliminated by the measure that the domestic water thermostat is an extremely sensitive Response differential, i.e. even the smallest temperature fluctuations cause the Effect thermostats. However, such thermostats are extremely expensive and sensitive to interference. The downside can be also partly eliminated by the fact that a differential pressure valve is provided, which at dispensing speeds substantially equal to the normal or When the dispensing speed are, the three-way valve in the sets the position leading to the once-through heat exchanger before this setting is made by the slow-reacting domestic water thermostat. At moderate dispensing speeds However, such a differential pressure valve does not work. In addition, such differential pressure valves are also expensive and sensitive to interference.

In summer, when space heating is not required, such a system is uneconomical because it is switched off the pump still has a given amount of heating medium at high temperature in the heat exchanger, the pipes and the three-way valve, the heat of which is lost due to the air flowing past these parts. The on High temperature heated parts of the heat generator also give a certain amount of heat to that in the heat exchanger dormant heating medium. This has the consequence that the heat exchanger is subject to a high thermal load.

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is thrown, whereby this amount of heat is also lost. These heat losses can be limited by attaching an electrically operated switch with which the User, if no hot water is required for a longer period of time, can switch off the hot water thermostat so that this can only be switched on using the differential pressure valve. Apart from the cost of such an electric one actuatable switch, such an arrangement is disadvantageous because it is not possible immediately Draw off hot service water, as in this case the through-flow heat exchanger is not kept at temperature, but can cool down and therefore when you tap again needs to be warmed up first. Another disadvantage is that in this case the hot water thermostat is bipolar Must be or as a unipolar thermostat with other devices (e.g. diodes) - must be combined, which entails high costs and does not reduce the reliability of the operation is conducive.

These disadvantages listed above are avoided by the device according to the invention is characterized in that the sensor of the domestic water he thermostats in the pipeline leading the domestic water Flow heat exchanger in one? Distance from their inlet end is arranged, which is determined by a predetermined Minimum drainage rate of the domestic water at which the thermostat should switch, and that the sensor of the boiler

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■ thermostats in the line for the heating medium between the Arranged heat exchanger of the heat generator and the three-way valve is.

These inventive measures reduce the temperature fluctuations of the domestic water is reduced considerably without the need for expensive and complicated facilities are needed.

The boiler thermostat, which can now switch the heat generator in all operating states, i.e. in summer and in winter operation, both when the heating medium circulates through the flow heat exchanger and through the space heater, and the domestic water thermostat, which controls the three-way valve or, if desired, the circulation pump or, if desired the heat generator switches, are preferably set so that the boiler thermostat when the heat exchanger is heated switches off before the domestic hot water thermostat reaches the Three-way valve switches to the position leading to the space heating elements. In addition, the device is preferred designed so that the circulation pump for the heating medium for a certain time after during summer operation after the boiler thermostat is switched off, i.e. until it is switched off ■ at a later point in time is switched off by the domestic hot water thermostat. Both measures are particularly beneficial for performance of the system and to prevent overheating of the normal

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wise to prevent formed as a lamellar heat exchanger. Due to these measures, the heated heating medium, which is still in the lines, is the heat exchanger and the circulation pump and also the heat content .der brought to high temperature parts of the heat exchanger (Lamellar block), after the heat generator has been switched off, still fed to the flow heat exchanger, so that heat losses be reduced.

The minimum dispensing speed at which the thermostat should switch is generally about 1.25 to 1.5 l / min. This minimum dispensing speed is chosen so that it is higher is the maximum possible leak rate that occurs in the event of defects or several dripping taps can to prevent the domestic water thermostat from being kept in the on position due to such leakage losses is, whereby the three-way valve in the to the flow heat exchanger leading position would be held and the room heating would be blocked. It should be noted that the dispensing speed with a single dripping tap or a dripping larger tap point can be about 0.3 l / min. on the other hand should be the minimum pumping speed at which the The domestic water thermostat switches the three-way valve to the position leading to the flow heat exchanger, be smaller than the lowest dispensing speed normally required by the user. The domestic water thermostat has preferably a large switching differential, i.e. it should preferably be at

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Switch it on at around 55 ° C and off at around o5 ° C.

To allow the boiler thermostat to respond quickly reach, this is preferably behind and as close as possible to the heat exchanger of the heat generator in the heating medium line arranged. The boiler thermostat is then preferably set to a switching temperature of about 90 ° C. and an on-off interval set of about 5 C.

Another advantage of the control device according to the invention is the fact that the switch is no longer is required, which is provided in the known systems of this type in order to control the temperature (keeping the heat supply) of the once-through heat exchanger for longer periods of time, e.g. at night, in order to avoid frequent switching of the three-way valve and the heat generator due to the rapid cooling, e.g. in less than an hour. In the control device according to the invention, the switch-on temperature of the domestic water thermostat (about 55 ° C) set to a lower value than with the known devices, and because the heat generator is switched off is done by the boiler thermostat, which is set to a high value (around 90 ° C), the heat generator It is switched much less frequently, even if no water is being drawn off.

An embodiment of the invention is described below explained in more detail with reference to the drawings.

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Fig. 1 shows a general scheme of the inventive Control device.

Fig. 2 shows a section through a once-through heat exchanger the device according to FIG. 1.

FIG. 3 shows an electrical circuit diagram for the device according to FIG. 1.

In the schematic representation according to B ¹ Ig. 1, reference number 1 denotes the heat generator and reference number 2 denotes an associated heat exchanger for the heating medium in the form of a lamellar block. The heating medium flows from the lamellar block 2 via the temperature limit switch 3 and the unipolar boiler thermostat 5 to the three-way valve 6 arranged. As can be seen from FIG. 1, the sensor of the boiler thermostat 5 is arranged in the line for the heating medium as close as possible to the lamellar block 2. The function of the temperature safety switch is to switch off the entire mechanism if the temperature of the heating medium should rise to such a high value due to a defect that it could lead to serious damage. This is the reason why the safety switch should be arranged closer to the lamellar block than the boiler thermostat.

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Fig. 2 shows in more detail the arrangement of the sensor of the domestic water thermostat in the flow heat exchanger. "As you can see from the drawing, this sensor 11 is in the line for the domestic water between two concentric, helically formed parts ″ or tube coils 12 and 13. The part 12 consists of an inner helically extending pipeline or snake, while the part 13 surrounds the part 12 concentrically on the outside and also forms a helical conduit or pipe coil. In this arrangement, the coils 12 and separated from each other by a cylindrically shaped sleeve 14. Domestic water is supplied at the lower end of part 12, while hot water is supplied at the lower end of part 13 is deducted.

The heating medium is fed in at 15 and withdrawn at 16. By accommodating the domestic hot water thermostat in the service water line, the low switch-on temperature of this thermostat (about 55 ° C), the arrangement according to the invention and mode of operation of the boiler thermostat as well as due to the usual thermal insulation of the flow heat exchanger generally 6 to 8 hours pass after the heat generator has been switched off before the water has cooled down that far has that-the heat generator switched on again and switched the three-way valve 6 in Fig. 1 to the other position will.

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Due to the arrangement of the P ¹ UhIers 11 between the pipe coils 12 and 13 in the straight part of the pipe coil 12, which is a particularly advantageous feature of the invention, it ensures that the domestic water thermostat 3 at a tap speed of 1.25 to 1 , 5 l / min switches on, which in practice is to be regarded as the minimum tap speed.

In Fig, 1 it is also indicated that in the supply line a simple control element 9 for the water flow rate, e.g. a regulating screw, is arranged for domestic water is. The heating medium flows after passing through the continuous heat exchanger 7 and the space heater back to the "ifär-exchanger 2 via the circulation pump 10. The gas supply for the heat generator (burner) is at 22 and the gas valve at 23 arranged.

In the electrical circuit diagram according to FIG. 3, they are already Parts shown in Figs. 1 and 2 are denoted by the same reference numerals. In addition to this are provided

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a relay 17 'to which a relay contact 17 belongs, a summer-winter switch 18, an indoor or outdoor thermostat 19s si * ¹ transformer 20, a rectifier 21 and some diodes 24. With reference to the circuit diagram it should be noted that in addition to one Arrangement with a normal internal thermostat also the use of an arrangement with an internal thermostat with remote control is possible. In such an arrangement

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The summer inter-switch is only superfluous because it is Switch is then included in the indoor thermostat with remote control.

The device according to the invention operates as follows. If the electrical circuit is connected to the electrical supply network, the Domestic water thermostat 8 cause the following switching operations: The circulation pump 10 is through the relay 17 and his

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Relay contact 17 switched on while the three-way valve 6 is switched to a position in which the heating medium flows through the domestic water heat exchanger. This results from the fact that the once-through heat exchanger for domestic water always has priority over space heating. Furthermore, the boiler thermostat 5 switches on the heat generator 1 by means of the gas valve 23.

After a given period of time, the boiler thermostat 5 reaches its switching temperature of about 90 ° C, at which the Heat generator 1 is switched off. However, the heating medium continues to circulate through the heat exchanger 7. About 30 seconds after the boiler thermostat 5 has reached its switching temperature of about 90 ° C, the domestic water is in the Continuous heat exchanger 7, the shutdown temperature of the domestic water thermostat reach, which is about 65 C. The latter will now switch the three-way valve to the position in which the heating medium is fed to the space heaters.

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Modern central heating systems are, often with one Summer-winter switch 18 provided. In this case, the circulation pump 10 will only work in the summer position when the temperature in the passage valve 7 increases v / should be grounded.

In the winter position, the pump 10 works continuously, and the boiler thermostat is activated after a certain time has elapsed after the switching processes mentioned above have cooled down a bit. When the internal thermostat 19 requests heating, the heat generator 1 is switched on again.

In the summer position, the circulation pump 10 is switched off, when the domestic water in the heat exchanger 7 has reached the shutdown temperature of the domestic water thermostat.

If no hot water is drawn off, the isolated The heat exchanger should only be cooled down enough after a very long period of time for the domestic water thermostat 8 to return switches on and the three-way valve 6 is switched back to the other position, the pump 10 in the summer starts up again and the heat generator 1 is switched on again.

If water for domestic use at a normal tapping speed is removed, which is about 6 l / min, in

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a system with an output of about 20.00Ü kcal / hour. at a temperature increase of 50 ° G, then the wrruclrv.'o.ßsertempere.tur and the temperature of the heating medium in dehi "V.-ärmetcuscher 7 will be equalized after some time. The latter temperature is kept lower than the abseiling temperature (jü C) of the Boilerthermostcteii 5 · over heat generator: he 1 remains in operation at this tapping speed, whereby the temperature of the heating medium remains at a constant value.

If the dispensing speed is reduced, the Equilibrium temperature of the heating medium increased. The value at which this temperature equals the switch-off temperature of the Boiler thermostat is "oscillation threshold" (reciprocating threshold). If the temperature of the heating medium just exceeds the switch-off temperature of the boiler thermostat 5, the heat generator 1 is periodically on and off, i.e. it begins to oscillate. In this case, the domestic water becomes less heat in the heat exchanger 7 record as the heating medium in the lamellar block 2 is supplied by the heat generator 1.

if hot water is being withdrawn at a very low speed is, - e.g. 1 l / min, then this small amount of water is already in the pipe section of the heat exchanger be well preheated that the domestic hot water thermostat 2u beginning does not switch and the three-way valve is initially in the

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Remains the position in which the heating medium is fed to the room radiators. However, when heat is withdrawn from the heat exchanger is, this will eventually cool so far that the thermostat of the heat exchanger now switches on again, whereby the three-way valve in the flow heat exchanger leading position is switched, the pump is switched on or kept in operation and also the heat generator switched on or kept in operation.

The control device according to the invention provides a simple and relatively inexpensive mechanism, without using a relatively expensive differential pressure switch, with relatively simple and cheap means to adjust the amount of water, e.g. a regulating screw, and without using any expensive precision thermostats ensures control that is very low Temperature fluctuations of the tap water at any desired Dispensing speed allows.

Furthermore, the boiler water thermostat forms an additional safeguard for the temperature of the heating medium during this Circulation through the heat exchanger and in the event of malfunctions in the three-way valve. In the known arrangements in which the The boiler thermostat is arranged in the line behind the three-way valve, such a fuse is missing.

. The present invention is not limited to the details

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th of the illustrated embodiment limited. The lines for the domestic water in the heat exchanger 7 can e.g. also be bent in an S-shape. It is only important that the pipe length between the entry point of the cold service water and the sensor of the domestic hot water thermostat is sufficient for the purposes of the present invention Length.

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Claims (9)

Claims 1. ) Control device for a central heating system with a heat generator, a circulation pump, an associated heat exchanger for the heating medium, supply lines for supplying the heating medium from the heat exchanger to space heaters and to a flow heat exchanger for domestic water, a three-way valve to control the heating medium either to the space heaters or to the flow heat exchanger, a boiler thermostat and a domestic water thermostat in the flow heat exchanger, which switches the three-way valve at a given temperature so that the heating medium - runs through the flow heat exchanger, and switches at a different temperature so that the heating medium flows through the room heater, characterized in that the sensor (11) of the domestic water thermostat (8) in the water line (12, 13) for the domestic water of the continuous heat exchanger (7) is arranged at a distance from its inlet end, which is determined by a predetermined minimum tap speed speed of the domestic water at which the thermostat (8) should switch, and that the sensor of the boiler thermostat (5) is arranged in the pipe for the heating medium between the heat exchanger (2) of the heat generator and the three-way valve (6). - 18 -309830/0479 2. Apparatus according to claim 1, characterized in that the boiler thermostat (5), which is the heat generator (1) switches, and the domestic water thermostat (8), which controls the three-way valve (6) or, if desired, the circulation pump (10) "or, if necessary, switches the heat generator (1), are set so that when the flow heat exchanger for domestic water is heated, the boiler thermostat (5) before the domestic hot water thermostat (8) switches off, whereby the circulation pump (10) after switching off the boiler thermostat and remains in operation until the domestic hot water thermostat is switched off, in summer operation or continuously in winter operation. 3. Control mechanism according to claim 1 or 2, with a single tap for domestic water, characterized in that the minimum tap speed at which the domestic water thermostat (8) should switch is about 0.3 l / min. 4. Control mechanism according to claim 1 or 2, with a plurality of taps for domestic water, characterized in that the minimum dispensing speed at which the domestic water thermostat (8) should switch is about 1.25 l / min. 5. Control mechanism according to one of claims 1 to 4, characterized in that the domestic water - 19 309830/0479 thermostat (8) switches on at a minimum hot water temperature of approx. 55 ° C and at a maximum temperature of about 65 ° G turns off. 6. Control mechanism according to claim 5, characterized in that the boiler thermostat (5) the The heat generator (1) switches off at a temperature of the heating medium of around 90 ° C. 7. Control mechanism according to claim 1, characterized in that the sensor of the boiler thermostat (5) is arranged behind and as close as possible to the heat exchanger (2) of the heat generator (1). 8. The control mechanism of claim 1, wherein the once-through heat exchanger for service water, an inner pipeline in the shape of a vessel and a concentric one connected to it has outer helical pipeline arranged for this purpose, characterized in that the sensor (11) of the water heater (8) in the transition between the inner and the outer pipe section (12,13) is arranged. 9. Control mechanism according to one of claims 1 to 8, characterized in that the boiler thermostat (5) is unipolar. - 2ü -. 309330/0479 Blank page