EP4141334A1 - Method for operating a heater, computer program, storage medium, regulation and control device, heater and use of a signal - Google Patents

Abstract

Method for operating a condensing heating system (1), having at least one heating water circuit (3) comprising at least one pump (2) with at least one heating element (4) and a bypass (5) which has a flow (6) and a return ( 7) bypassing the at least one heating element (4), the bypass (5) being openable and closable by means of a valve (8) that can be actuated by differential pressure, the method comprising at least the following steps;a) detecting a setpoint modulation value of the condensing heating system (1), b) sensory detection of an incipient flow through the bypass (5), c) maintaining the operation of the pump (2) at a predetermined power over a period of time, d) reducing the power of the pump (2) when a predetermined modulation setpoint is reached. Next, a condensing boiler (1) and a computer program are proposed.

Description

The present invention relates to a method for operating a condensing heating system. Furthermore, a condensing heating system is proposed, as well as a computer program that supports the execution of the method in a condensing heating system.

In particular, the technical field of gas-fired condensing heating systems or condensing boilers is addressed here. Gas-fired condensing heating systems or condensing boilers are used in particular to supply heating systems in apartments, houses, etc. with heating water as required, which is routed to the radiators by means of a corresponding hot water circulation system, where it gives off its heat and then returns to the condensing heating system. there to be warmed up again.

Such condensing heating systems usually have at least one pump which is provided in a (closed) heating water circuit. With the pump, hot water is pumped through the hot water circuit, preferably regulated depending on the desired heat output of the radiator. The hot water circuit can include at least one, but preferably also several, heaters. Once multiple radiators, such as bps. Radiators are provided, they can be connected in parallel or be traversed by heating water.

Most modern condensing heating systems work modulating. In particular, this means that the output of the boiler or burner of the condensing heating system adapts to the heat output actually required during operation. Such Adaptation or regulation preferably takes place steplessly. The particular aim of this modulation is to work in an energy-saving manner, because the more precisely the power generated corresponds to the required heat output, the more efficiently the resources, in particular the fuel gas, can be used efficiently. It can be provided that the condensing heating system has a regular modulation setpoint, for example in the range of approx. 80%, which is initially set before the heating output of the condensing heating system is then adapted to the requested heat output as part of a modulation control process .

During the operation of such a condensing heating system, situations can arise that produce a significant increase in pressure in the heating water circuit. A main reason for a significant increase in pressure in the heating water circuit is closing radiator valves. The significant increase in pressure in the heating water circuit is also accompanied by a reduction in the heating water volume flow. In order to distribute the thermal energy generated by the heater to the heating system, a defined minimum heating water volume flow can be specified. If this falls below, the heater would stop heating. Therefore, in this situation, the control circuit increases the set value for the pump so as not to fall below the minimum heating water volume flow. The pressure generated by the pump cannot simply be "reduced" via the system, so that the pressure difference between the flow and return increases as a result.

In order to remedy such situations, it is known to provide a bypass which connects a flow of the heating water to the radiators and a return for the heating water, bypassing the at least one radiator. Therefore, when the bypass is open, heating water can flow directly from the flow to the return without flowing through a radiator. It is also known that a differential-pressure-actuable valve is provided in this bypass, which valve can be opened and closed automatically can close, depending on the pressure difference in the bypass upstream and downstream of the valve. For this purpose, the valve can be equipped with a spring and a predetermined spring force or spring characteristic, so that the valve opens at a predetermined differential pressure. If the difference is lower, the valve remains closed and the bypass cannot flow through. Such an increased differential pressure can occur precisely in the situation described above, so that in this case the bypass opens and a further increase in pressure is avoided.

The provision of the bypass has proven to be particularly suitable if the heating water circulation is too low or the differential pressures are too high, since this could cause the flow temperatures to rise to the point of boiling and/or clearly noticeable or audible vibrations on the thermostatic valves.

With conventional system boilers and also with so-called combi-boilers, i.e. condensing heating systems which, in addition to heating water, also provide or heat up service water, e.g. for showers or other sanitary applications, can have further technical problems.

So far it has not been possible to react to an opening of the bypass as needed or with variable pump performance, which means that some disadvantages in maintaining safety have to be accepted. For example, it is necessary to raise the return temperature when the bypass is opened and when the warm flow water is mixed with the cold return water. In heaters with a bypass according to the prior art, the pumps are operated largely unregulated or regulated in stages, which on the one hand leads to increased electrical consumption and on the other hand to the bypass being damaged accordingly is often permanently open during unregulated pump operation. Pumps also emit annoying noises, especially at high speeds.

The object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, a method for operating a condensing heating system is to be specified, which works more gently and/or more energy-efficiently. Furthermore, a condensing boiler suitable for this purpose, a computer program and a computer-readable medium are to be proposed.

These objects are achieved with the method for operating a condensing heating system according to claim 1, a condensing heating system according to claim 7, a computer program according to claim 9 and a computer-readable medium according to claim 10. Advantageous developments are specified in the dependent claims. It should be pointed out that the features listed in the claims can be combined with one another in any technologically meaningful manner and show further refinements of the invention. The description, in particular in connection with the figures, explains the invention and specifies further exemplary embodiments and details.

The operating method proposed here can be carried out in a condensing heating system which has at least one heating water circuit comprising at least one pump with at least one radiator and a bypass which connects a flow and a return, bypassing the at least one radiator. The bypass can be opened and closed by means of a valve that can be actuated by differential pressure. The condensing heating system is set up in particular to circulate the water in the heating water circuit by means of the pump, so that the so-called heating water flows through the at least one radiator in regular operation. Furthermore, the condensing heating system has, in particular, a so-called gas-fired condensing boiler, where the heating water fed there is heated by means of a gas furnace. The heating water thus heated reaches the radiator via the flow at an increased temperature, flows through it, gives off a large part of its heat and is then routed back to the combustion chamber. As already explained, several heating elements can be provided, which preferably form parallel water flow paths.

1. a) Erfassen eines Modulationssollwertes der Brennwert-Heizanlage,
2. b) sensorisches Feststellen einer einsetzenden Durchströmung des Bypasses,
3. c) Aufrechterhalten des Betriebs der Pumpe mit einer vorgegebenen Leistung über einen Zeitraum,
4. d) Reduzieren der Leistung der Pumpe, wenn ein vorgegebener Modulationssollwert erreicht ist.

The process includes at least the following steps:

1. a) detection of a modulation target value of the condensing heating system,
2. b) sensory detection of an incipient flow through the bypass,
3. c) maintaining the operation of the pump at a specified power over a period of time,
4. d) reducing the power of the pump when a predetermined modulation setpoint is reached.

It is possible that the steps listed here take place sequentially or one after the other, in the order given here a), b), c), d). However, it is also possible for the steps to overlap at least in part in terms of time.

For example, it is possible for step a) to be carried out intermittently or continuously throughout the entire method, ie the modulation target value is recorded practically continuously. In particular, step a) takes place during so-called regular operation, ie in the state when the bypass is closed.

In step b), it is now determined by sensors when a bypass flow begins, ie when the valve that can be actuated by differential pressure opens and heating water can therefore flow through the bypass. The sensory determination includes, in particular, the detection of parameters or progression parameters of the operation of the condensing heating system that are characteristic of the opening process of the valve or the bypass that can be actuated by differential pressure are. In particular, limit values or tolerance thresholds are provided for this purpose, and if they are reached or exceeded or fallen below, this results in the direct determination of an incipient flow through the bypass. It can be of particular importance that the sensory determination takes place very quickly, for example within a few seconds, for example within a maximum of 30 seconds or even within a maximum of 10 seconds. In particular, it is possible that the sensory determination is already present before the full throughput has been reached through the bypass, which the valve that can be actuated by differential pressure can maximally release.

The pump performance of the pump in the heating water circuit is preferably stabilized or maintained immediately after step b). This can mean in particular that the usually power-modulated pump in step c) does not have a varying power but is operated with a constant power. In particular, this output can correspond to that which is present at the moment when the onset of flow through the bypass is determined. It is also possible that the specified power is a power that is increased compared to normal operation, for example at approximately 90% or even approximately 95%. Maintaining this predetermined performance lasts in particular until the overall process is stabilized again. The control circuit of the pump is or remains deactivated as long as the bypass is open. Closing the bypass depends on the state of the heating system.

If the process is stabilized, which can also be detected or ascertained, for example, by sensors using various parameters or progression parameters of the condensing heating system, step d) can be initiated. The power of the pump is then reduced when a predetermined modulation target value is reached. The predefined modulation target value can be a predetermined value, but it is also possible for this value to be determined and predetermined from a parallel measurement in accordance with step a).

It is preferred that in step d) the output of the pump is reduced step by step until the valve that can be actuated by differential pressure closes. In particular, a routine can be stored which, possibly depending on the current operating situation of the condensing heating system, specifies the reduction steps (magnitude and/or periods of time). However, the reduction in the output of the pump again leads to an equalization of the overall pressure conditions in the heating water circuit, so that if stabilization is successful, the valve that can be actuated by differential pressure closes automatically and flow through the bypass no longer takes place.

It is possible that in step b) the reaching of a limit value is determined by sensors using a parameter from the following group: heating water volume flow, heating water system pressure, heating water temperature in the return. In particular, means and/or measures can be provided by means of which a current heating water volume flow, a current heating water system pressure and/or a current heating water temperature in the return of the heating water circuit can be determined. Here, too, it is possible to compare these currently sensor-determined parameters with a predetermined (fixed or variably adaptable) limit value. For example, it is possible to conclude that the bypass is opening if the current heating water volume flow in a predetermined area, e.g. in the return of the heating water circuit, reaches or exceeds a predetermined limit value for the heating water volume flow. It is also possible for the heating water system pressure to fall below a specified limit value in the supply line or to rise above a specified limit value in the return line in order to conclude that flow through the bypass is starting. It is also possible to detect a temperature increase in the return flow using a specified limit value.

However, not only concrete values, but possibly also parameters over time can be checked in the context of step b). It is thus possible to use sensors to detect when a limit value has been reached for at least one course parameter from the following group determine: heating water volume flow change, heating water system pressure change, heating water temperature change in the return. Consequently, a temporal evaluation (speed of change) is taken into account here.

It is obvious that parameters and course parameters can also be used together or alternately for this purpose.

It is possible that a setpoint modulation value present before step b) approximately corresponds to the setpoint setpoint modulation specified in step d). For example, the setpoint modulation value determined immediately before step b) in step a) can be stored and then specified as a specification for the setpoint modulation value at the start of the reduction in the power of the pump in accordance with step d).

It is also possible that, after step d), the pump is again operated at regular power.

The advantage of the invention is in particular a pump control that reduces the opening of the bypass to a minimum. It uses a volume flow control by means of a corresponding pump and sensors and includes a detection for the opening of the bypass, the monitoring and stabilization of the existing device operation and the controlled return to regular pump operation in the event of an increasing heat requirement and the associated closing of the bypass.

As long as the bypass is closed and the entire heating water volume flow flows into the radiators, the system is linear from a control point of view. Accordingly, control algorithms for linear systems can be used for volume flow control until the bypass is opened.

From a control point of view, opening the bypass represents a non-linearity and is characterized in particular by a sudden increase in the heating water volume flow. This sudden increase can be determined directly or indirectly with the appropriate sensors. A second plausibility-checking indicator for the opening of the bypass is the rise in temperature of the heating water in the return, because this heating water is mixed with the heating water flowing in from the flow via the bypass at a significantly higher temperature. The temperature increase can exceed a threshold value or reach an empirical value within a defined period of time and in the steady state with regard to a measured temperature and the current modulation as well as the pump output.

If these two states in particular (volume flow jump and return temperature rise) are detected in a defined time sequence, an open bypass can be assumed. Alternatively, it is also possible to use a (sudden) change in the heating water system pressure (falling flow, rising return) instead of the increase in volume flow to determine when flow through the bypass is starting.

After detection of the opening of the bypass and to stabilize the process, the output of the pump is kept constant at the specified output level that led to the opening of the bypass. In particular, this can also be done in order to prevent so-called "toggling", ie a continuously repeated opening and closing of the bypass.

Furthermore, the modulation setpoint of the condensing heating system can be monitored for an increase that corresponds to the thermal power requirement before the bypass is opened. If this value is reached, the previously constant pump output can be reduced again.

In the last phase, the power of the pump is reduced step by step until the control setpoint of the pump power is preferably reached. It can then be assumed that the bypass now closes again.

Since the target value of the thermal power requirement had previously increased, it can be assumed that valves on the heaters or radiators are open again, which means that the previously high hydraulic pressure loss that led to the opening of the bypass is now lower and is increased by pump control low performance level is possible without opening the bypass.

According to a further aspect, a condensing heating system is proposed, which has at least one heating water circuit comprising at least one pump with at least one radiator and a bypass. The bypass connects a supply line and a return line, bypassing the at least one heating element, and can be opened and closed by means of a valve that can be actuated by differential pressure. Means are also provided which are set up in such a way that they can carry out the steps of the method described here. These means can be, for example, a regulation and control unit and at least one sensor. Sensors used in particular in step b) are selected from the group consisting of temperature sensors, pressure sensors and volumetric flow sensors.

Furthermore, a computer program is also proposed, which comprises commands which cause the condensing boiler of the type mentioned above to carry out the steps of the method in the manner disclosed here. Finally, a computer-readable medium can also be provided, on which the computer program mentioned here is stored.

Fig.1:

den Aufbau einer Brennwert-Heizanlage, und

Fig.2:

ein Diagramm zur Veranschaulichung von Heizanlagenparameter während des Betriebes.

The invention and the technical environment are explained in more detail below with reference to a figure. It should be noted that this figure is schematic in nature and is not intended to limit the invention as a whole. Show it:

Fig.1:

the construction of a condensing heating system, and

Fig.2:

a diagram to illustrate heating system parameters during operation.

1 shows a condensing heating system 1, which is set up in particular to carry out the method outlined here. In this schematic illustration, the condensing heating system 1 has a combustion chamber 13 at the top in the central region. This can be equipped with a primary heat exchanger so that, for example, the heating water entering this boiler is preheated via a gas furnace as required. The heated hot water flows from there (here to the left), whereby the temperature of the heating water in the flow 6 can be determined or recorded by means of a temperature sensor 10. The direction of flow 17 is repeatedly characterized by small arrows. The heating water then flows past a pressure sensor 11, and then flows on to (distant) heating elements 4, which are shown here in the manner of radiators.There in the radiators 4, the heating water releases its heat and then flows back to the combustion chamber 13. For this circulation of the heating water is a power-modulating pump 2. A volume flow sensor 12 is provided downstream of this power-modulating pump 2, which is also arranged here in the return 7 of the heating water circuit 3. Shortly before entry into the combustion chamber 13, another temperature sensor 10 is provided, by means of which the temperature of the heating water can be determined is.

A bypass 5 is also provided here, which directly connects the flow 6 to the return 7, bypassing the radiators 4 with one another. In this bypass 5 a differential pressure actuable valve 8 is provided. It should also be noted that this figure 1 a so-called gas-fired combi-device is concerned, so that in addition to the pure heating water circulation, another heat exchanger 16 is also traversed in parallel by the heating water, with which an external water line 15 can also be heated. It is thus possible, for example, to heat water for taps, showers or other sanitary facilities with the heating water from this condensing heating system 1 . An additional 3-way valve 14 is provided in order to be able to combine these parallel streams with one another again as required and in a controlled manner.

In addition, a regulation and control unit 9 is provided in the outlined housing of the condensing heating system 1 . This can, for example, receive or process signals or measured values from the sensors, in particular the temperature sensors 10, the pressure sensor 11 and/or the volume flow sensor 12. It is also possible that this regulation and control unit can influence or control the processes or operating parameters of the combustion chamber 13 , the pump 2 and/or the 3-way valve 14 . The regulation and control unit 9 can be set up in such a way that it executes the steps outlined above of the method proposed here. So e.g. B. possible that the detection of the modulation setpoint of the condensing heating system 1 and the combustion chambers 13 is processed there. Since the regulation and control unit 9 acts together with the sensors, it can also determine when the flow through the bypass 5 begins or the (autonomous) differential-pressure-operated valve 8 opens. It is also possible for the regulating and control unit 9 to regulate the operation of the pump 2 when such a flow through the bypass 5 is detected, in particular by maintaining a power output over a predetermined period of time. Likewise, the regulation and control unit 9 can then decide or specify according to predetermined criteria if the power of the pump is to be (gradually) reduced again.

2 shows a diagram to illustrate heating system parameters during the operation of a condensing heating system, in particular during the implementation of the procedure proposed here. The diagram shows the flow temperature Tv, return temperature Tr, heating water volume flow V, modulation setpoint Msw and pump setpoint Psw parameters over time t. In order to illustrate the parallelism or the time offset here, these curves (without a unit and not true to scale) are shown one above the other.

In a first phase of operation, the reduction in heating water volume flow V explained above can be determined. If the heating water volume flow V reaches a specified limit value, the pump setpoint Psw is (automatically) increased (marked as time t ₁ in the diagram), which is accompanied by an immediate pressure increase in the heating water circuit. The pressure generated by the pump now also leads to the described pressure difference between flow and return, whereby at the time of the (automatic) opening of the valve that can be actuated by differential pressure (see time t ₂ in the diagram), the heating water volume flow V increases significantly or even almost abruptly, the flow temperature Tv falls and the return temperature Tr rises. Therefore, by sensory detection of this characteristic course, it is possible to conclude that flow is starting to flow through the bypass, cf. step b) of the method proposed here. Now, for a further phase, the setpoint pump value Psw present at time t ₂ is kept constant and the setpoint modulation value Msw varies. In particular, when the flow temperature Tv reaches a desired (constant) value again and/or the modulation setpoint Msw reaches a desired (constant) value again (see point in time t ₃ in the diagram), the condensing heating system is again in a stationary state and monitoring of the modulation setpoint Msw or the pump power Psw begins. When the bypass closes - which depends on the state of the heating system and is no longer shown here - the pump control loop is activated again, with the pump setpoint Psw being lowered in stages if necessary (no longer shown here).

Reference List

1

Condensing heating system

2

pump

3

heating water circulation

4

radiator

5

bypass

6

leader

7

return

8th

differential pressure operated valve

9

Regulating and control unit

10

temperature sensor

11

pressure sensor

12

flow rate sensor

13

combustion chamber

14

three-way valve

15

water pipe

16

heat exchanger

17

flow direction

tv

flow temperature

Tr

return temperature

V

heating water flow rate

VAT

modulation setpoint

PSW

pump setpoint

t

Time

Claims (10)

Method for operating a condensing heating system (1), having at least one heating water circuit (3) comprising at least one pump (2) with at least one heating element (4) and a bypass (5) which has a flow (6) and a return ( 7) bypassing the at least one heating element (4), the bypass (5) being openable and closable by means of a differential pressure-actuable valve (8), the method comprising at least the following steps; a) detection of a modulation target value of the condensing heating system (1), b) sensory detection of an incipient flow through the bypass (5), c) maintaining the operation of the pump (2) at a predetermined power over a period of time, d) reducing the power of the pump (2) when a predetermined setpoint modulation value is reached. Method according to Claim 1, in which, in step d), the output of the pump (2) is reduced step by step until the valve (8) which can be actuated by differential pressure closes. Method according to claim 1 or 2, wherein in step b) the reaching of a limit value of at least one parameter from the following group is detected by sensors: heating water volume flow, heating water system pressure, heating water temperature in the return. Method according to one of the preceding claims, wherein in step b) the reaching of a limit value of at least one course parameter from the following group is determined by sensors: heating water volume flow change, heating water system pressure change, heating water temperature change in the return. Method according to one of the preceding claims, in which a desired modulation value present before step b) corresponds approximately to the predetermined desired modulation value in step d). Method according to one of the preceding claims, in which, after step d), the pump (2) is operated at regular power. Condensing heating system (1), having at least one heating water circuit (3) comprising at least one pump (2) with at least one radiator (4) and a bypass (5) which bypasses a flow (6) and a return (7). of the at least one heating element (4) with one another, wherein the bypass (5) can be opened and closed by means of a valve (8) that can be actuated by differential pressure, and means that are set up to carry out the steps of a method from one of the preceding claims. Condensing heating system (1) according to claim 7, wherein a regulating and control unit (9) and at least one sensor (10, 11, 10) are provided. A computer program comprising instructions which cause the condensing boiler (1) of claim 7 to carry out the steps of a method according to any one of claims 1 to 6. A computer-readable medium storing the computer program of claim 9.

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