Method for operating a heater, computer program, storage medium and heater

Abstract

A method for operating a condensing boiler heating system (1) comprising at least one heating water circulation system (3) with at least one pump (2), at least one radiator (4), and a bypass (5) which connects a flow (6) and a return (7) bypassing the at least one radiator (4), wherein the bypass (5) can be opened and closed by means of a differential pressure-operated valve (8), the method comprising at least the following steps: a) detecting a modulation setpoint of the condensing boiler heating system (1), b) sensorily detecting the commencement of flow through the bypass (5), c) maintaining the operation of the pump (2) at a predetermined power output over a period of time, d) reducing the power output of the pump (2) when a predetermined modulation setpoint is reached. Furthermore, a condensing boiler heating system (1) and a computer program are proposed.

Description

[0001] The present invention relates to a method for operating a condensing boiler heating system. Furthermore, a condensing boiler heating system is proposed, as well as a computer program that supports the execution of the method in a condensing boiler heating system.

[0002] This section specifically addresses the technical field of gas-fired condensing boilers and condensing boilers. Gas-fired condensing boilers and condensing boilers are primarily used to supply heating systems in apartments, houses, etc., with hot water as needed. This hot water is circulated to the radiators, where it releases its heat before returning to the boiler to be reheated.

[0003] Such condensing boiler systems typically have at least one pump integrated into a (closed) hot water circulation system. This pump circulates hot water through the system, preferably regulated according to the desired heating output of the radiators. The hot water circulation system can include at least one, but preferably several, radiators. When multiple radiators are used, they can be connected in parallel or have a continuous flow of hot water through them.

[0004] Most modern condensing boilers operate in a modulating mode. This means, in particular, that the output of the boiler or burner of the condensing boiler adjusts to the actual heat output required during operation. This adjustment or regulation is preferably stepless. The primary goal of this modulation is to save energy, because the more closely the generated output matches the required heat output, the more efficiently resources, especially fuel gas, can be used. The condensing boiler can therefore be designed with a regular modulation setpoint, for example, around 80%, which is initially set before the heating output of the condensing boiler is subsequently adjusted to the required heat output as part of a modulation control process.

[0005] During the operation of such a condensing boiler system, situations can arise that generate a significant pressure increase in the heating water circulation. A primary cause of this significant pressure increase is the closing of radiator valves. This significant pressure increase is accompanied by a reduction in the heating water flow rate. To distribute the thermal energy generated by the boiler to the heating system, a defined minimum heating water flow rate may be specified. If this minimum is undershot, the boiler would shut down. Therefore, in this situation, the control loop increases the setpoint for the pump to ensure the minimum heating water flow rate is not undershot. The pressure generated by the pump cannot be easily released through the system, thus increasing the pressure differential between the flow and return lines.

[0006] To remedy such situations, it is known to provide a bypass that connects a supply line of heating water to the radiators and a return line of heating water, bypassing at least one radiator. Therefore, when the bypass is open, heating water can flow directly from the supply line to the return line without passing through a radiator. It is also known that this bypass incorporates a differential pressure-operated valve that can open and close automatically, depending on the pressure difference 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 curve, so that the valve opens at a predetermined differential pressure. If the differential is below this threshold, the valve remains closed, and thus the bypass is blocked.Such an increased differential pressure can occur precisely in the situation described above, so that in this case the bypass opens and a further pressure increase is avoided.

[0007] The provision of a bypass has proven particularly suitable when insufficient heating water circulation or excessively high differential pressures could occur, as this could cause the flow temperatures to rise to boiling and / or clearly noticeable or audible vibrations to occur at the thermostatic valves.

[0008] Conventional system boilers, as well as so-called combi boilers (i.e., condensing boilers), which provide or heat not only heating water but also domestic hot water, e.g., for showers or other sanitary applications, may exhibit further technical problems.

[0009] Currently, it is not possible to respond to the opening of the bypass with variable pump output or on demand, which necessitates accepting several disadvantages in terms of safety. For example, opening the bypass and mixing warm supply water with cold return water requires raising the return temperature. This reduces the condensation of water vapor in the exhaust gas, a process inherent in condensing boilers, and consequently, temporarily lowers efficiency. In state-of-the-art heating systems with bypasses, the pumps are largely unregulated or operated in stages. This leads to increased electrical consumption and often results in the bypass being permanently open due to the unregulated pump operation. Furthermore, pumps, especially at high speeds, emit disruptive noise.

[0010] DE 10 2012 003 502 A1 proposes using a flow meter in conjunction with a modulating pump to determine the system differential pressure based on a characteristic map. If the differential pressure exceeds a value close to the overflow valve opening pressure, the pump speed is reduced, thus preventing the valve from opening. A disadvantage of this method is the need for a flow meter, which, due to tolerances, can lead to deviations in the determined system differential pressure. Furthermore, the method cannot account for changes in the overflow valve opening pressure that occur, for example, due to aging.

[0011] 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 boiler heating system is to be provided that operates more gently and / or more energy-efficiently. Furthermore, a suitable condensing boiler heating system, a computer program, and a computer-readable medium are to be proposed.

[0012] These problems are solved by the method for operating a condensing boiler according to claim 1, a condensing boiler according to claim 7, a computer program according to claim 8, and a computer-readable medium according to claim 9. Advantageous embodiments are specified in the dependent claims. It should be noted that the features listed in the claims can be combined with one another in any technologically meaningful way, and further embodiments of the invention are shown. The description, particularly in conjunction with the figures, explains the invention and provides further embodiments and specifications.

[0013] The operating procedure proposed here can be implemented in a condensing boiler system that has at least one heating water circulation loop, including at least one pump, with at least one radiator and a bypass connecting a flow and a return, bypassing the at least one radiator. The bypass can be opened and closed by means of a differential pressure-operated valve. The condensing boiler system is specifically designed to circulate the water in the heating water loop using the pump, so that the heating water flows through the at least one radiator during normal operation. Furthermore, the condensing boiler system includes a gas-fired condensing boiler, where the supplied heating water is heated by a gas burner.The heated water, now at an elevated temperature, flows through the supply line to the radiator, passes through it, releases a large portion of its heat, and is then returned to the combustion chamber. As previously explained, multiple radiators can be used, preferably with parallel water flow paths.

[0014] The procedure includes at least the following steps: a) Determining a modulation setpoint of the condensing boiler during normal operation of the condensing boiler, b) Sensory detection of the onset of flow through the bypass, c) Maintaining the operation of the pump at a predetermined power over a period of time, d) Reducing the power of the pump when a predetermined modulation setpoint is reached.

[0015] The steps listed here will proceed sequentially, in the order given here a), b), c), d). However, it is also possible that the steps may overlap, at least partially.

[0016] For example, step a) can be executed intermittently or continuously throughout the entire process, meaning the modulation setpoint is practically continuously recorded. Step a) takes place during normal operation, i.e., when the bypass is closed.

[0017] In step b), a sensor detects when bypass flow begins, i.e., when the differential pressure-operated valve opens and heating water can flow through the bypass. This sensor detection includes, in particular, the identification of parameters or operating parameters of the condensing boiler that are characteristic of the opening process of the differential pressure-operated valve or the bypass. Specifically, limit values ​​or tolerance thresholds are defined for this purpose; reaching or exceeding / falling below these thresholds immediately triggers the detection of flow through the bypass. It is particularly important that the sensor detection occurs very quickly, for example, within a few seconds, such as within a maximum of 30 seconds or even within a maximum of 10 seconds.In particular, it is possible that the sensory detection is already present before the full throughput through the bypass is reached, which the differential pressure-actuated valve can release at most.

[0018] Preferably immediately following step b), the pump output of the pump in the heating water circulation is stabilized or maintained. This can mean, in particular, that the pump, which is usually power-modulated, does not exhibit varying output during step c), but operates at a constant output. This output can correspond, in particular, to the output present at the moment the bypass flow is detected. It is also possible that the specified output is higher than that of normal operation, for example, at approximately 90% or even approximately 95%. Maintaining this specified output continues, in particular, until the overall process has stabilized again. The pump's control loop is or remains deactivated as long as the bypass is open. Closing the bypass depends on the state of the heating system.

[0019] Once the process has stabilized, which can be detected, for example, by sensors monitoring various parameters or trend parameters of the condensing boiler, step d) can be initiated. In this step, the pump output is reduced when a predefined modulation setpoint is reached. This predefined modulation setpoint can be a predetermined value, or it can be determined and predetermined based on a parallel measurement as described in step a).

[0020] Preferably, in step d) the pump output is gradually reduced until the differential pressure-operated valve closes. In particular, a routine can be defined which, possibly depending on the current operating situation of the condensing boiler, specifies the reduction steps (size and / or time intervals). However, the reduction in pump output again leads to an equalization of the overall pressure conditions in the heating water circulation, so that if stabilization is successful, the differential pressure-operated valve closes automatically and thus no further flow through the bypass occurs.

[0021] It is possible that in step b), the reaching of a limit value is detected by a sensor using a parameter from the following group: heating water flow rate, heating water system pressure, heating water return temperature. In particular, means and / or measures can be provided to determine the current heating water flow rate, the current heating water system pressure, and / or the current heating water return temperature. Here, too, it is possible to compare these currently sensor-determined parameters with a predefined (fixed or variably adjustable) limit value. For example, it is possible to infer that the bypass should open if the current heating water flow rate in a predetermined range, e.g., in the return of the heating water system, reaches or exceeds a predefined limit value for the heating water flow rate.It is also possible for the heating water system pressure in the flow line to fall below a predefined limit or in the return line to rise above a predefined limit, in order to indicate the start of flow through the bypass. Similarly, it is possible to detect a temperature increase in the return line based on a predefined limit.

[0022] However, not only specific values, but also, if applicable, temporal parameters can be checked within step b). For example, it is possible to use sensors to detect when a limit value of at least one parameter from the following group is reached: heating water flow rate change, heating water system pressure change, heating water return temperature change. Consequently, a temporal evaluation (rate of change) is taken into account here.

[0023] It is obvious that parameters and trend parameters can also be used together or alternately for this purpose.

[0024] It is possible that a modulation setpoint existing before step b) corresponds approximately to the specified modulation setpoint in step d). For example, the modulation setpoint determined in step a) immediately before step b) can be saved and then specified as the modulation setpoint for starting the pump power reduction according to step d).

[0025] It is still possible that after step d) the pump will resume operation at regular power.

[0026] The advantage of the invention is, in particular, a pump control system that minimizes the opening of the bypass. It utilizes flow rate control via a suitable pump and sensors and includes detection of the bypass opening, monitoring and stabilization of the device operation during this time, and a controlled return to regular pump operation when heat demand increases, thus closing the bypass.

[0027] As long as the bypass is closed and the entire flow of heating water is directed to the radiators, the system is considered linear from a control engineering perspective. Therefore, control algorithms for linear systems can be used to regulate the flow rate until the bypass opens.

[0028] From a control engineering perspective, opening the bypass represents a non-linearity and is characterized in particular by a sudden increase in the heating water flow rate. This sudden increase can be detected directly or indirectly using appropriate sensors. A second plausible indicator for the opening of the bypass is the temperature rise of the heating water in the return line, because this heating water is mixed with heating water flowing in from the supply line via the bypass at a significantly higher temperature. Within a defined time period, as well as during steady-state conditions with respect to a measured temperature, the current modulation, and the pump output, the temperature rise can exceed a threshold value or reach a value based on experience.

[0029] If these two conditions (volume flow rate increase and return temperature rise) are detected in a defined temporal sequence, it can be assumed that the bypass is open. Alternatively, instead of the volume flow rate increase, a (sudden) change in the heating water system pressure (falling flow, rising return) can also be used to determine whether the bypass is now open.

[0030] Once the bypass has opened, and to stabilize the process, the pump's output is maintained at the predetermined level that triggered the bypass opening. This is particularly important to prevent "toggling," i.e., the bypass repeatedly opening and closing.

[0031] Furthermore, the modulation setpoint of the condensing boiler can be monitored for an increase that corresponds to the thermal output demand before the bypass opens. Once this value is reached, the previously constant pump output can be reduced again.

[0032] In the final phase, the pump's output is gradually reduced until the target pump output is reached. At this point, it can be assumed that the bypass will close again.

[0033] Since the target value for thermal power demand has increased previously, it can be assumed that valves on the radiators have been opened again, which means that the previously high hydraulic pressure loss that led to the opening of the bypass is now lower and can be achieved by pump control at a low power level without opening the bypass.

[0034] According to another aspect, a condensing boiler heating system is proposed, which has at least one heating water circulation loop with at least one pump, at least one radiator, and a bypass. The bypass connects a flow and a return, bypassing the at least one radiator, and can be opened and closed by means of a differential pressure-operated valve. Furthermore, means are provided that are configured to carry out the steps of the procedure described here. These means include a control unit and at least one sensor. The sensors used, in particular in step b), are selected from the groups of temperature sensor, pressure sensor, and flow sensor.

[0035] Furthermore, a computer program is proposed which includes commands that cause the condensing boiler of the aforementioned type to execute the steps of the method disclosed herein. Finally, a computer-readable medium may also be provided on which the aforementioned computer program is stored.

[0036] The invention and its technical context are explained in more detail below with reference to a figure. It should be noted that this figure is schematic and is not intended to limit the invention as a whole. It shows: Fig. 1: the structure of a condensing boiler heating system, and Fig. 2: a diagram illustrating heating system parameters during operation.

[0037] Fig. 1 Figure 1 shows a condensing boiler 1, which is specifically designed to carry out the procedure outlined here. In this schematic representation, the condensing boiler 1 has a combustion chamber 13 in the central area at the top. This chamber can be equipped with a primary heat exchanger, so that, for example, heating water entering this boiler via a gas burner is preheated as required. From there, the heated hot water flows (here to the left), with the temperature of the heating water in the flow line 6 being determined or recorded by a temperature sensor 10. The flow direction 17 is indicated by small arrows. The heating water then flows past a pressure sensor 11 and continues to (distant) radiators 4. There, in the radiators 4, the heating water releases its heat and then flows back to the combustion chamber 13.A power-modulating pump 2 is provided for this circulation of the heating water. A flow sensor 12 is provided downstream of this power-modulating pump 2, which is also located in the return line 7 of the heating water circulation 3. A temperature sensor 10 is provided shortly before the water enters the combustion chamber 13, allowing the temperature of the heating water to be determined.

[0038] Furthermore, a bypass 5 is provided here, which directly connects the flow 6 to the return 7, bypassing the radiators 4. A differential pressure-operated valve 8 is provided in this bypass 5. It should also be noted that Figure 1 depicts a so-called gas-fired combination unit, meaning that in addition to the pure heating water circulation, the heating water also flows through another heat exchanger 16 in parallel, which can also heat an external water line 15. This makes it possible, for example, to heat domestic hot water for taps, showers, or other sanitary fixtures with the heating water from this condensing boiler 1. To be able to combine these parallel flows as needed and in a controlled manner, an additional 3-way valve 14 is provided.

[0039] Furthermore, a control unit 9 is provided in the sketched housing of the condensing boiler 1. This unit can, for example, receive and process signals or measured values ​​from the sensors, in particular the temperature sensors 10, the pressure sensor 11, and / or the flow sensor 12. It is also possible for this control unit to influence or control the processes or operating parameters of the combustion chamber 13, the pump 2, and / or the 3-way valve 14. The control unit 9 can be configured to perform the steps of the procedure proposed here, as outlined above. For example, it is possible for the acquisition of the modulation setpoint of the condensing boiler 1 or the combustion chambers 13 to be processed there. Since the control unit 9 works together with the sensors, it can also detect when the flow through the bypass 5 begins or when the (self-contained) differential pressure-operated valve 8 opens.Furthermore, the control unit 9 can regulate the operation of pump 2 upon detecting such a flow through bypass 5, in particular by maintaining a certain output level for a specified period. Likewise, the control unit 9 can then decide or specify, according to predefined criteria, when the pump output is to be reduced again (gradually).

[0040] Fig. 2 Figure 1 shows a diagram illustrating heating system parameters during the operation of a condensing boiler, particularly during the implementation of the method proposed here. The diagram schematically depicts the progression of the parameters flow temperature Tv, return temperature Tr, heating water flow rate V, modulation setpoint Msw, and pump setpoint Psw over time t. To illustrate parallelism or temporal offset, these progressions (unitless and not to scale) are superimposed.

[0041] In the first phase of operation, the reduction in the heating water flow rate V described earlier can be observed. When the heating water flow rate V reaches a predefined limit, the pump setpoint Psw is (automatically) increased (marked as time t1 in the diagram), which is accompanied by an immediate pressure increase in the heating water circulation. The pressure generated by the pump now also leads to the described pressure difference between the flow and return. At the time the differential pressure-operated valve opens (see time t2 in the diagram), the heating water flow rate V increases significantly or even almost abruptly, the flow temperature Tv drops, and the return temperature Tr rises. Therefore, by sensor detection of this characteristic curve, it can be concluded that flow through the bypass has begun; see step b) of the procedure proposed here.For a further phase, the pump setpoint Psw present at time t2 is held constant, and the modulation setpoint Msw is varied. Specifically, when the flow temperature Tv reaches a desired (constant) value again and / or the modulation setpoint Msw reaches a desired (constant) value again (see time t3 in the diagram), the condensing boiler system is back in a steady state, and monitoring of the modulation setpoint Msw or the pump output Psw begins. When the bypass closes—which depends on the state of the heating system and is not illustrated here—the pump control loop is reactivated, possibly with the pump setpoint Psw being reduced in stages (not shown here). Reference symbol list

[0042] 1 Condensing boiler 2 Pump 3 Heating water circulation 4 Radiator 5 Bypass 6 Flow 7 Return 8 Differential pressure-operated valve 9 Control unit 10 Temperature sensor 11 Pressure sensor 12 Flow sensor 13 Combustion chamber 14 Three-way valve 15 Water pipe 16 Heat exchanger 17 Flow direction Tv supply temperature Tr return temperature V heating water flow rate Msw modulation setpoint Psw pump setpoint t time

Claims

1. Method for operating a condensing boiler heating system (1), comprising at least one heating water circulation system (3) comprising at least one pump (2) with at least one radiator (4) and a bypass (5), which connects a flow pipe (6) and a return pipe (7) to each other, bypassing the at least one radiator (4), wherein the bypass (5) can be opened and closed by means of a differential pressure-operated valve (8), characterised in that the method comprises at least the following steps, which are performed sequentially in the order specified here a), b), c), d) a) Detecting a modulation setpoint of the condensing boiler heating system (1) during control operation of the condensing boiler heating system (1), b) sensory detection of an onset of flow through the bypass (5), c) Maintaining the operation of the pump (2) at a predetermined output over a period of time, d) reducing the output of the pump (2) when a predetermined modulation setpoint is reached.

2. Method according to claim 1, wherein in step d) the output of the pump (2) is gradually reduced until the differential pressure-operated valve (8) closes.

3. 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 a sensor: heating water volume flow, heating water system pressure, heating water temperature in the return flow.

4. Method according to one of the previous claims, wherein in step b) the reaching of a limit value of at least one process parameter from the following group is detected by a sensor : heating water volume flow change, heating water system pressure change, heating water temperature change in the return flow.

5. Method according to one of the previous claims, wherein a modulation setpoint value present before step b) corresponds approximately to the specified modulation setpoint value in step d).

6. Method according to one of the previous claims, wherein after step d), the pump (2) is operated at regular power.

7. Condensing boiler system (1) comprising at least one heating water circulation system (3) comprising at least one pump (2) with at least one radiator (4) and a bypass (5) which connects a flow pipe (6) and a return pipe (7) to each other, bypassing the at least one radiator (4), wherein the bypass (5) can be opened and closed by means of a differential pressure-operated valve (8), a control and regulation unit (9), at least one sensor (10, 11, 12) and means which are designed to carry out the steps of a method according to one of the preceding claims.

8. Computer program comprising instructions that cause the condensing boiler system (1) of claim 7 to perform the steps of a method according to one of claims 1 to 6.

9. Computer-readable medium on which the computer program according to claim 8 is stored.

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