CA2000867C - Method of setting the mean value of the supply temperature of a heating medium and circuit for performing the method - Google Patents
Method of setting the mean value of the supply temperature of a heating medium and circuit for performing the methodInfo
- Publication number
- CA2000867C CA2000867C CA002000867A CA2000867A CA2000867C CA 2000867 C CA2000867 C CA 2000867C CA 002000867 A CA002000867 A CA 002000867A CA 2000867 A CA2000867 A CA 2000867A CA 2000867 C CA2000867 C CA 2000867C
- Authority
- CA
- Canada
- Prior art keywords
- heating
- supply temperature
- value
- temperature
- characteristic function
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000010438 heat treatment Methods 0.000 title claims abstract description 90
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000007704 transition Effects 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 230000001105 regulatory effect Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 101100536354 Drosophila melanogaster tant gene Proteins 0.000 description 1
- 241000534944 Thia Species 0.000 description 1
- 240000004543 Vicia ervilia Species 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000005485 electric heating Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D19/00—Details
- F24D19/10—Arrangement or mounting of control or safety devices
- F24D19/1006—Arrangement or mounting of control or safety devices for water heating systems
- F24D19/1009—Arrangement or mounting of control or safety devices for water heating systems for central heating
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1917—Control of temperature characterised by the use of electric means using digital means
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1927—Control of temperature characterised by the use of electric means using a plurality of sensors
- G05D23/193—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces
- G05D23/1932—Control of temperature characterised by the use of electric means using a plurality of sensors sensing the temperaure in different places in thermal relationship with one or more spaces to control the temperature of a plurality of spaces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Remote Sensing (AREA)
- Steam Or Hot-Water Central Heating Systems (AREA)
- Control Of Temperature (AREA)
- Domestic Hot-Water Supply Systems And Details Of Heating Systems (AREA)
- Measuring Volume Flow (AREA)
- Instantaneous Water Boilers, Portable Hot-Water Supply Apparatuses, And Control Of Portable Hot-Water Supply Apparatuses (AREA)
- Infusion, Injection, And Reservoir Apparatuses (AREA)
Abstract
In a method of setting the mean value of the supply temperature (T V) of a heating medium which is intermittently heated by a heating apparatus (5) in a heating system comprising at least one adjustable throttling point (16, 17, 18) for the heating medium, a desired supply temperature value (T S) is determined on the basis of external influencing factors (H, T external) and the heating medium is heated to the desired supply temperature value (T S) with the throttling points (16, 17, 18) fully open. The mean value of the supply temperature is to be controlled to such a value that an optimum total throughflow rate of the heating medium is achieved, i.e. the throttling points formed by thermostatic. radiator valves are to be partially open. For this purpose, a starting function is determined with which the temporary temperature (T V) changes during heating, at least one parameter (C m) of this starting function is changed to fix a desired function, and the desired supply temperature value T F is changed until the course of heating has matched the desired function in each heating-up phase.
Description
DANFOSS A/S, DK-6430 NORDBORG
Method of setting the mean value of the supply temperature of a heating medium and a circuit for performing the method The invention relates to a method of setting the mean value of the supply temperature of a heating medium which is intermittently heated by a heating apparatus in a heating system comprising at least one adjustable throttling point for the heating medium, wherein a desired supply temperature value is determined on the basis of external influencing factors and the heating medium is heated to the desired supply temperature value with the throttling points fully open. In addition, the invention relates to a circuit for performing the method.
In such a method, the anticipated heat requirement of the system is e~timated by external influences such as the external temperature, temperature difference between the supply and return temperature or a predetermined room temperature in a central room of a house. From these measured or given values, a supply temperature is calculated together with a manually adjustable heating curve. A disadvantage of this method is that changes in the actual load conditions are not taken into account. When using thermostatic valves at the throttling points, e.g. at the inlets to the radiators, this leads to the con-dition that the thermo~tatic valves are always fully open when the supply temperature is too low and are for the most part closed when . ~.
the supply temperature is too high so a~ to reach the desired room temperature. An excessively high supply temperature gives rise to a high energy loss whereas a supply temperature which is too low will not adequately heat the rooms even though the radiator valves are open.
What is desired is a supply temperature at which the thermostatic radiator valves can still exercise a regulating function, i.e. they are in a partially open or partially throttling condition.
DE-OS 33 45 949 discloses an apparatus for controlling a central heating system which seeks to determine this ideal supply temperature by measuring the changes in the thermal resistance with the aid of temperature and flow measuring sensors. However, because of the many measuring sensors, this solution requires a relatively high investment cost.
It is the problem Or the invention to provide an automatic regulating method for setting the mean value of the supply temperature to such a value that an optimum total throughflow rate is achieved for the heating medium.
In a method of the aforementioned kind, this problem is solved in that a starting function with which the supply temperature changes on heating is determined, at least one parameter of this starting function is changed to fix a desired function, and the desired supply temperature value is changed until the course of heating has adapted itself to the desired function in each heating phase.
According to the invention, therefore, the load on the heating system in the "run-in condition" is determined by the changing rate of the supply temperature. If a lot Or heating medium is required, i.e. if the supply temperature rises only slowly, then the radiator valves are open too far, that is to say they are not in the optimum regulat-ing range. In that case, the mean value of the supply temperature must therefore be increased. When starting a heating system, one can fundamentally assume that the thermostatic valves are fully open.
The load on the boiler is therefore 100% because the maximum-possible amount of heating medium flows through the system. With such a load condition, the supply temperature will rise only slowly because a large amount of heating medium has to be heated by a constant heat output. The starting function is determined in this operating con-dition. After a certain time, the rooms are heated and the thermo-static valves start to throttle. When such a normal operation has been reached, the course of the supply temperature at each start of the heating apparatus will be steeper than during the initial maximum load situation. The course of heating of the supply temperature in this normal case in relation to the initially determined maximum load curve is an expression for the flow rate at which the installation operates and whether the supply temperature is correctly set. By presetting the desired function corresponding to the optimum heating course and thus the optimum flow rate and by matching the actual supply temperature course to this desired function, one obtains an optimum flow rate and the correct mean value for the supply temper-ature.
"~W
Advantageously, no additional measuring equipment is required because generally temperature sensors are available for measuring the supply and return temperatures. By reason of the automatic operation of the method, frequent resetting of the curve is possible. The heating system can therefore be adapted to fluctuations necessitated by the seasons of the year. The return temperature can also be determined without its own return temperature sensor if a pumping phase precedes each start of the heating apparatus. If the heating phase lasts long enough, the heating medium is fed into the supply conduit at the return temperature. The temperature sensor in the supply conduit therefore determines the return temperature which is stored for calculating the starting or desired function.
In a preferred embodiment of the method, the starting or desired function with which the supply temperature changes is matched by the following auxiliary function:
K -C . t m k ) + TR
wherein TV(t) is the supply temperature, PK is the maximum heat output of the boiler, Cm is the thermal capacity of the throughgoing water, t is the time, Ck is the thermal capacity of the boiler, and TR is the return temperature ,~J
~... ~
.,"_ This auxiliary function gives a sufficiently accurate approach to the actually desired course of the supply temperature. Since heating will generally be in accordance with the e function on starting, the steepness and the ratio of the gradients between the starting function and desired function are easily determined. In the stated auxiliary function, the parameters are readily determined because it is sufficient to determine each parameter combination PK/Cm and Cm/Ck.
Preferably, the parameters of the starting function are determined on at least three occasions by measuring the ~upply temperature. This gives an adequate number of values for fixing the auxiliary function.
Advantageously, the desired function is determined from the starting function by changing, especially reducing, the parameter Cm. This parameter governs the gradient of the curve representing the course of the temperature.
By reducing the parameter C , the curve becomes steeper. This means a lower throughflow quantity. However, with a lower throughflow quantity, the supply temperature must be higher so that an adequate amount of heat is transferred by the heating apparatus to the radiators.
An optimum setting at which the thermostatic radiator valves are partially throttled is obtained when the parameter C in the desired function is about 20% to 40% smaller than the parameter Cm of the starting function. This means that a correspondingly smaller amount '~ ,~, ...
of the heating medium flows through the heating system, i.e. only about 60% to 80% of the largest possible amount.
Advantageously, the starting function is determined during each transition from night-time to daytime operation. This permits daily resetting of the desired function. The heating system can thus better follow the inclusion or switching off of a plurality of radiators and/or seasonally governed fluctuations in the heat require-ment.
Preferably, a predetermined dead period is provided between determin-ing the starting function and fixing the desired function. This dead period amounts to at least one heating-up cycle and preferably more than one. This ensures that heating up of the rooms is not delayed.
With advantage, the difference between the changed desired supply temperature value and the existing supply temperature value is used to form an input quantity for an integrator which switches the heating apparatus on and off by way of a hysteresis switch. Such a hysteresis switch is for example known from DE-PS 34 26 937. This method facilitates simple regulation.
Preferably, the threshold values for the hysteresis switch are deter-mined from the parameters of the desired function. This represents an advantageous additional use of the parameters of the auxiliary function. The mean value of the supply temperature can be easily adapted to the desired set values by varying the threshold values of the hysteresis switch.
According to the invention, provision i~ also made for a clrcuit for performing the method, comprising pre-setting means which produce a desired supply temperature value signal as a result of external influencing factors, an integrator which is supplied with a difference between a modified desired supply temperature value signal and an existing supply temperature value signal, a hysteresis switch which produces a boiler control signal for switching the heating apparatus when the integrator output signal exceeds a first predetermined value or falls below a second predetermined value, parameter identification means which determine the parameters of the starting function, a computer which calculates the desired function and forms the difference between the desired function and the measured heating course of the heating medium, an error signal producing unit which, depending on the desired function formed in the computer and the determined difference, forms an error and, depending on this error, produces three temperature signal values of which at least one is positive and one is negative, and a summating unit which adds the temperature signal values each time the boiler is switched off, the output of the summating unit being added to the output of the presetting means.
Advantageously, the three temperature signal values correspond to a temperature change of -0.2~, 0~ and +0.2~ C. The rate of change of the changed desired supply temperature value is therefore relatively small. The heating system can readily follow the change.
A preferred example of the invention will now be described in conjunc-tion with the drawing in which the single figure is a diagrammatic representation of the heating system.
~_ - 8 The heating system comprises for example three radiators 13, 14, 15 which are supplied by a supply conduit 11 with hot water from a boller 5. After flowing through the radiators 13, 14, 15, the water returns to the boiler 5 through a return conduit 12. The amount of water flowing through each radiator 13, 14, 15 is determined by a respective valve 16, 17, 18. These valves 16, 17, 18 are in the form of conventional thermostatic valves, i.e. their degree of opening depends on the temperature of the room which the radiator heats. If the temperature in this room is below the set desired temperature, the thermostatic radiator valve opens and, if it is higher, the valve throttles the supply Or hot water in the radiator.
As usual, the boiler 5 comprises a heating apparatus, for example an oil, gas or like burner or an electric heating apparatus and a storage vessel for water.
The supply temperature TV and the return temperature TR are measured at the supply conduit 11 and return conduit 12 or in the boiler 5, for example with the aid of a thermometer 25 with a connected measurement convertor which converts a temperature value into electric signals supplied via conduits 19, 20 and 23 for further processing. Although two separate temperature sensors will give more accurate measurements of the supply and return temperatures, it is sufficient to have a single temperature sensor (not shown) for the supply temperature. To determine the return temperature, prior to each starting of the heating apparatus, the heating medium in the boiler is then pumped around in the heating circuit for a certain time so that the supply temperature is equal to the return temperature. This supply temperature is then _ g _ stored and then utilised for the next heating period as a constant return temperature.
To control the boiler, i.e. to set the mean value of the supply temper-ature Tv, provision is made for pre-setting means t in which a desired supply temperature valueTs is formed from several external influencing factors such as the external temperature TeXternal and a curve gradient H. The quantity TS can, for example, be formed according to a known formula in which S ( external) 22 2/H
In this formula, H is the gradient of the curve, a comparatively low mean supply temperature being reached with a low H value whereas a higher mean supply temperature value is reached with a higher H value.
This desired value i~ changed into a modified desired value TF in a summating point 2 by a correcting quantity that will be described hereinafter. By wayofasignal conduit 20, the existing value of the supply temperature TV is derived at a differential formation point 29 from this modified desired value TF. This difference is fed to the input of an integrator 3. The integrator 3 integrates this signal over the time. The output of the integrator 3 is fed to a hysteresis switch 4 which switches the heating apparatus of the boiler 5 off when the output value of the integrator 3 exceeds a predetermined first value and switches the heating apparatus of the -boiler 5 on again when the output value of the integrator falls below a predetermined second value.
In the heating-up phase, i.e. when the heating apparatus heats the water, the time heating course of the supply temperature TV can be expressed by the following auxiliary function TV(t) = - ( 1 - exp m ) + TR
m k wherein TV(t) is the supply temperature, PK is the maximum heat output of the boiler, C is the thermal capacity of the throughgoing water, t is the time, Ck is the thermal capacity of the boiler, and TR is the return temperature.
Parameter identification means 7 determine the supply temperature TV
at several different instances, preferably on three occasions, and from these determine the parameters PK, C and Ck. In order to fix the auxiliary function precisely, it is generally sufficent to deter-mine only the quotients PK/C and C ICk. As input quantities, the parameter identification means 7 are fed with a time signal, the supply temperature TV by way of a signal conduit 26 which communicates with the signal conduit 19, and the return temperature TR by way of a signal conduit 24 which communicates with the signal conduit 23. The parameter identification means 7 operate only when the heating liquid is heated for the first time, for example upon transition from night-time to daytime operation. The parameters that are determined in theparameter identification means 7 therefore define a starting function.
,~, ~.
The parameters are transmitted to a computer 6 where they can be modified to form a desired function. During a subsequent heating-up cycle, a desired function is formed with the aid of the modified parameters and represents the desired time course of heating the supply temperature Tv. This computed course of TV is fed by way of a signal conduit 28 to a differential formation point 8 to which is fed the value of the supply temperature TV by way of a signal conduit 27 communicating with the signal conduit 19. At the differential form-ation point 8, therefore, the difference is formed between th~ calcul-ated value of TV and the measured value of Tv. This difference is fed to an error signal producing unit 9. This error signal producing unit 9 determines an error from the difference calculated at the differen-tial forma~ion point 8 and the values of the desired function supplied by way of a signal conduit 30. At its output, the error signal pro-duction unit 9 emits three temperature signal values A depending on the determined error, namely according to the following rule. If the error lies between -2% and +2%, A = 0. If the amount of the error is larger than 2%, A = 0.2 C. The sign of A depends on the sign of the error.
The output of the error production unit 9 is added in a summating unit 10 during each stop of the heating apparatus of the boiler 5. The output of the summating unit 10 is added at the summating point 2 to the output TS of the presetting means 1. At the summating point 2, a change or modified desired supply temperature value TF is therefore formed. During normal operation, this modified desired supply temper-ature value TF is used in the above described manner to form a differ-i~, 5 _r~
CA 02000867 1998-02-ll ence together with the existing supply temperature TV that is then fed to the integrator 3.
The heating system operates as follows. When the system is switched from night-time reduced operation to normal daytime conditions, one can assume that all radiator thermostats 16, 17, 18 are fully open and the maximum amount of water flows through the radiators 13, 14, 15.
The boiler 5 i~ started. The supply temperature TV thereupon rises and is measured. With the aid of the measured curve, the constants PK, Cm, Ck of the auxiliary function of the heating system can be calculated in the parameter identification unit 7, for example with the aid of a microprocessor. Since these constants are calculated upon starting the heating system, one therefore obtains a starting function, i.e. an equation, which applies for the heating system at 100% flow.
With the aid of this starting function, a desired function can now be calculated by inserting for example a new value for C . The new value can for example be 20% to 40%, particularly 30%, smaller than in the starting function. The object Or the regulator formed by the integrat-or 3, the hysteresis switch 4, the boiler 5, the return conduit 20 and the differential formation point 26 is, now, to set a mean value for the supply temperature such that the supply temperature TV keeps within the modified desired supply temperature value TF given by the desired curve. If the supply temperature TV has the desired course, one obtains a throughflow amounting to about 60% to 80% preferably 70%, of the maximum throughflow. At this throughflow, the thermostatic valves 16, 17, 18 of the radiators are in a partially throttling condition, i.e. they can react to temperature changes in the room by opening further or more throttling and thereby fulfil their regulating function.
After each stopping of the boiler, i.e. after each switching off of the heating apparatus, the measured temperature course of the supply temperature TV is compared with the calculated desired function at several points. Depending on the result of this comparison,-the mean value of the supply temperature is held con~tant raised by 0.2 C or reduced by -0.2 C. This change is so small that the system has adequate time to become set to the new marginal conditions. ThiA
adaptation of the mean value to the lQad is carried out as long as the day-time operation is set.
An additional advantage of the system is that, from the calculated constants C , Ck and PK, one can determine a so called alpha value which can be fed to the hysteresis switch 4 by way of a signal conduit 31. This alpha value ~erves to fix or change the two predetermined threshold values for which, when exceeded or fallen below, a boiler control signal ls produced for switching the heatlng apparatus. This avoids a somewhat uncertain manual setting of this value.
Loading of the system is therefore not only estimated but the actual consumed heat consumption is determined. The supply temperature TV is so controlled that the radiator thermostats can always remain in their regulating range despite changing external conditions.
The external temperature TeXter al and the curve gradient H fed to the presetting means 1 are also continued to be used during daytime oper-ation to modify the desired value TS depending on the external con-ditions. This input of the summating point 2 does therefore not have to be necessarily constant throughout the day.
Method of setting the mean value of the supply temperature of a heating medium and a circuit for performing the method The invention relates to a method of setting the mean value of the supply temperature of a heating medium which is intermittently heated by a heating apparatus in a heating system comprising at least one adjustable throttling point for the heating medium, wherein a desired supply temperature value is determined on the basis of external influencing factors and the heating medium is heated to the desired supply temperature value with the throttling points fully open. In addition, the invention relates to a circuit for performing the method.
In such a method, the anticipated heat requirement of the system is e~timated by external influences such as the external temperature, temperature difference between the supply and return temperature or a predetermined room temperature in a central room of a house. From these measured or given values, a supply temperature is calculated together with a manually adjustable heating curve. A disadvantage of this method is that changes in the actual load conditions are not taken into account. When using thermostatic valves at the throttling points, e.g. at the inlets to the radiators, this leads to the con-dition that the thermo~tatic valves are always fully open when the supply temperature is too low and are for the most part closed when . ~.
the supply temperature is too high so a~ to reach the desired room temperature. An excessively high supply temperature gives rise to a high energy loss whereas a supply temperature which is too low will not adequately heat the rooms even though the radiator valves are open.
What is desired is a supply temperature at which the thermostatic radiator valves can still exercise a regulating function, i.e. they are in a partially open or partially throttling condition.
DE-OS 33 45 949 discloses an apparatus for controlling a central heating system which seeks to determine this ideal supply temperature by measuring the changes in the thermal resistance with the aid of temperature and flow measuring sensors. However, because of the many measuring sensors, this solution requires a relatively high investment cost.
It is the problem Or the invention to provide an automatic regulating method for setting the mean value of the supply temperature to such a value that an optimum total throughflow rate is achieved for the heating medium.
In a method of the aforementioned kind, this problem is solved in that a starting function with which the supply temperature changes on heating is determined, at least one parameter of this starting function is changed to fix a desired function, and the desired supply temperature value is changed until the course of heating has adapted itself to the desired function in each heating phase.
According to the invention, therefore, the load on the heating system in the "run-in condition" is determined by the changing rate of the supply temperature. If a lot Or heating medium is required, i.e. if the supply temperature rises only slowly, then the radiator valves are open too far, that is to say they are not in the optimum regulat-ing range. In that case, the mean value of the supply temperature must therefore be increased. When starting a heating system, one can fundamentally assume that the thermostatic valves are fully open.
The load on the boiler is therefore 100% because the maximum-possible amount of heating medium flows through the system. With such a load condition, the supply temperature will rise only slowly because a large amount of heating medium has to be heated by a constant heat output. The starting function is determined in this operating con-dition. After a certain time, the rooms are heated and the thermo-static valves start to throttle. When such a normal operation has been reached, the course of the supply temperature at each start of the heating apparatus will be steeper than during the initial maximum load situation. The course of heating of the supply temperature in this normal case in relation to the initially determined maximum load curve is an expression for the flow rate at which the installation operates and whether the supply temperature is correctly set. By presetting the desired function corresponding to the optimum heating course and thus the optimum flow rate and by matching the actual supply temperature course to this desired function, one obtains an optimum flow rate and the correct mean value for the supply temper-ature.
"~W
Advantageously, no additional measuring equipment is required because generally temperature sensors are available for measuring the supply and return temperatures. By reason of the automatic operation of the method, frequent resetting of the curve is possible. The heating system can therefore be adapted to fluctuations necessitated by the seasons of the year. The return temperature can also be determined without its own return temperature sensor if a pumping phase precedes each start of the heating apparatus. If the heating phase lasts long enough, the heating medium is fed into the supply conduit at the return temperature. The temperature sensor in the supply conduit therefore determines the return temperature which is stored for calculating the starting or desired function.
In a preferred embodiment of the method, the starting or desired function with which the supply temperature changes is matched by the following auxiliary function:
K -C . t m k ) + TR
wherein TV(t) is the supply temperature, PK is the maximum heat output of the boiler, Cm is the thermal capacity of the throughgoing water, t is the time, Ck is the thermal capacity of the boiler, and TR is the return temperature ,~J
~... ~
.,"_ This auxiliary function gives a sufficiently accurate approach to the actually desired course of the supply temperature. Since heating will generally be in accordance with the e function on starting, the steepness and the ratio of the gradients between the starting function and desired function are easily determined. In the stated auxiliary function, the parameters are readily determined because it is sufficient to determine each parameter combination PK/Cm and Cm/Ck.
Preferably, the parameters of the starting function are determined on at least three occasions by measuring the ~upply temperature. This gives an adequate number of values for fixing the auxiliary function.
Advantageously, the desired function is determined from the starting function by changing, especially reducing, the parameter Cm. This parameter governs the gradient of the curve representing the course of the temperature.
By reducing the parameter C , the curve becomes steeper. This means a lower throughflow quantity. However, with a lower throughflow quantity, the supply temperature must be higher so that an adequate amount of heat is transferred by the heating apparatus to the radiators.
An optimum setting at which the thermostatic radiator valves are partially throttled is obtained when the parameter C in the desired function is about 20% to 40% smaller than the parameter Cm of the starting function. This means that a correspondingly smaller amount '~ ,~, ...
of the heating medium flows through the heating system, i.e. only about 60% to 80% of the largest possible amount.
Advantageously, the starting function is determined during each transition from night-time to daytime operation. This permits daily resetting of the desired function. The heating system can thus better follow the inclusion or switching off of a plurality of radiators and/or seasonally governed fluctuations in the heat require-ment.
Preferably, a predetermined dead period is provided between determin-ing the starting function and fixing the desired function. This dead period amounts to at least one heating-up cycle and preferably more than one. This ensures that heating up of the rooms is not delayed.
With advantage, the difference between the changed desired supply temperature value and the existing supply temperature value is used to form an input quantity for an integrator which switches the heating apparatus on and off by way of a hysteresis switch. Such a hysteresis switch is for example known from DE-PS 34 26 937. This method facilitates simple regulation.
Preferably, the threshold values for the hysteresis switch are deter-mined from the parameters of the desired function. This represents an advantageous additional use of the parameters of the auxiliary function. The mean value of the supply temperature can be easily adapted to the desired set values by varying the threshold values of the hysteresis switch.
According to the invention, provision i~ also made for a clrcuit for performing the method, comprising pre-setting means which produce a desired supply temperature value signal as a result of external influencing factors, an integrator which is supplied with a difference between a modified desired supply temperature value signal and an existing supply temperature value signal, a hysteresis switch which produces a boiler control signal for switching the heating apparatus when the integrator output signal exceeds a first predetermined value or falls below a second predetermined value, parameter identification means which determine the parameters of the starting function, a computer which calculates the desired function and forms the difference between the desired function and the measured heating course of the heating medium, an error signal producing unit which, depending on the desired function formed in the computer and the determined difference, forms an error and, depending on this error, produces three temperature signal values of which at least one is positive and one is negative, and a summating unit which adds the temperature signal values each time the boiler is switched off, the output of the summating unit being added to the output of the presetting means.
Advantageously, the three temperature signal values correspond to a temperature change of -0.2~, 0~ and +0.2~ C. The rate of change of the changed desired supply temperature value is therefore relatively small. The heating system can readily follow the change.
A preferred example of the invention will now be described in conjunc-tion with the drawing in which the single figure is a diagrammatic representation of the heating system.
~_ - 8 The heating system comprises for example three radiators 13, 14, 15 which are supplied by a supply conduit 11 with hot water from a boller 5. After flowing through the radiators 13, 14, 15, the water returns to the boiler 5 through a return conduit 12. The amount of water flowing through each radiator 13, 14, 15 is determined by a respective valve 16, 17, 18. These valves 16, 17, 18 are in the form of conventional thermostatic valves, i.e. their degree of opening depends on the temperature of the room which the radiator heats. If the temperature in this room is below the set desired temperature, the thermostatic radiator valve opens and, if it is higher, the valve throttles the supply Or hot water in the radiator.
As usual, the boiler 5 comprises a heating apparatus, for example an oil, gas or like burner or an electric heating apparatus and a storage vessel for water.
The supply temperature TV and the return temperature TR are measured at the supply conduit 11 and return conduit 12 or in the boiler 5, for example with the aid of a thermometer 25 with a connected measurement convertor which converts a temperature value into electric signals supplied via conduits 19, 20 and 23 for further processing. Although two separate temperature sensors will give more accurate measurements of the supply and return temperatures, it is sufficient to have a single temperature sensor (not shown) for the supply temperature. To determine the return temperature, prior to each starting of the heating apparatus, the heating medium in the boiler is then pumped around in the heating circuit for a certain time so that the supply temperature is equal to the return temperature. This supply temperature is then _ g _ stored and then utilised for the next heating period as a constant return temperature.
To control the boiler, i.e. to set the mean value of the supply temper-ature Tv, provision is made for pre-setting means t in which a desired supply temperature valueTs is formed from several external influencing factors such as the external temperature TeXternal and a curve gradient H. The quantity TS can, for example, be formed according to a known formula in which S ( external) 22 2/H
In this formula, H is the gradient of the curve, a comparatively low mean supply temperature being reached with a low H value whereas a higher mean supply temperature value is reached with a higher H value.
This desired value i~ changed into a modified desired value TF in a summating point 2 by a correcting quantity that will be described hereinafter. By wayofasignal conduit 20, the existing value of the supply temperature TV is derived at a differential formation point 29 from this modified desired value TF. This difference is fed to the input of an integrator 3. The integrator 3 integrates this signal over the time. The output of the integrator 3 is fed to a hysteresis switch 4 which switches the heating apparatus of the boiler 5 off when the output value of the integrator 3 exceeds a predetermined first value and switches the heating apparatus of the -boiler 5 on again when the output value of the integrator falls below a predetermined second value.
In the heating-up phase, i.e. when the heating apparatus heats the water, the time heating course of the supply temperature TV can be expressed by the following auxiliary function TV(t) = - ( 1 - exp m ) + TR
m k wherein TV(t) is the supply temperature, PK is the maximum heat output of the boiler, C is the thermal capacity of the throughgoing water, t is the time, Ck is the thermal capacity of the boiler, and TR is the return temperature.
Parameter identification means 7 determine the supply temperature TV
at several different instances, preferably on three occasions, and from these determine the parameters PK, C and Ck. In order to fix the auxiliary function precisely, it is generally sufficent to deter-mine only the quotients PK/C and C ICk. As input quantities, the parameter identification means 7 are fed with a time signal, the supply temperature TV by way of a signal conduit 26 which communicates with the signal conduit 19, and the return temperature TR by way of a signal conduit 24 which communicates with the signal conduit 23. The parameter identification means 7 operate only when the heating liquid is heated for the first time, for example upon transition from night-time to daytime operation. The parameters that are determined in theparameter identification means 7 therefore define a starting function.
,~, ~.
The parameters are transmitted to a computer 6 where they can be modified to form a desired function. During a subsequent heating-up cycle, a desired function is formed with the aid of the modified parameters and represents the desired time course of heating the supply temperature Tv. This computed course of TV is fed by way of a signal conduit 28 to a differential formation point 8 to which is fed the value of the supply temperature TV by way of a signal conduit 27 communicating with the signal conduit 19. At the differential form-ation point 8, therefore, the difference is formed between th~ calcul-ated value of TV and the measured value of Tv. This difference is fed to an error signal producing unit 9. This error signal producing unit 9 determines an error from the difference calculated at the differen-tial forma~ion point 8 and the values of the desired function supplied by way of a signal conduit 30. At its output, the error signal pro-duction unit 9 emits three temperature signal values A depending on the determined error, namely according to the following rule. If the error lies between -2% and +2%, A = 0. If the amount of the error is larger than 2%, A = 0.2 C. The sign of A depends on the sign of the error.
The output of the error production unit 9 is added in a summating unit 10 during each stop of the heating apparatus of the boiler 5. The output of the summating unit 10 is added at the summating point 2 to the output TS of the presetting means 1. At the summating point 2, a change or modified desired supply temperature value TF is therefore formed. During normal operation, this modified desired supply temper-ature value TF is used in the above described manner to form a differ-i~, 5 _r~
CA 02000867 1998-02-ll ence together with the existing supply temperature TV that is then fed to the integrator 3.
The heating system operates as follows. When the system is switched from night-time reduced operation to normal daytime conditions, one can assume that all radiator thermostats 16, 17, 18 are fully open and the maximum amount of water flows through the radiators 13, 14, 15.
The boiler 5 i~ started. The supply temperature TV thereupon rises and is measured. With the aid of the measured curve, the constants PK, Cm, Ck of the auxiliary function of the heating system can be calculated in the parameter identification unit 7, for example with the aid of a microprocessor. Since these constants are calculated upon starting the heating system, one therefore obtains a starting function, i.e. an equation, which applies for the heating system at 100% flow.
With the aid of this starting function, a desired function can now be calculated by inserting for example a new value for C . The new value can for example be 20% to 40%, particularly 30%, smaller than in the starting function. The object Or the regulator formed by the integrat-or 3, the hysteresis switch 4, the boiler 5, the return conduit 20 and the differential formation point 26 is, now, to set a mean value for the supply temperature such that the supply temperature TV keeps within the modified desired supply temperature value TF given by the desired curve. If the supply temperature TV has the desired course, one obtains a throughflow amounting to about 60% to 80% preferably 70%, of the maximum throughflow. At this throughflow, the thermostatic valves 16, 17, 18 of the radiators are in a partially throttling condition, i.e. they can react to temperature changes in the room by opening further or more throttling and thereby fulfil their regulating function.
After each stopping of the boiler, i.e. after each switching off of the heating apparatus, the measured temperature course of the supply temperature TV is compared with the calculated desired function at several points. Depending on the result of this comparison,-the mean value of the supply temperature is held con~tant raised by 0.2 C or reduced by -0.2 C. This change is so small that the system has adequate time to become set to the new marginal conditions. ThiA
adaptation of the mean value to the lQad is carried out as long as the day-time operation is set.
An additional advantage of the system is that, from the calculated constants C , Ck and PK, one can determine a so called alpha value which can be fed to the hysteresis switch 4 by way of a signal conduit 31. This alpha value ~erves to fix or change the two predetermined threshold values for which, when exceeded or fallen below, a boiler control signal ls produced for switching the heatlng apparatus. This avoids a somewhat uncertain manual setting of this value.
Loading of the system is therefore not only estimated but the actual consumed heat consumption is determined. The supply temperature TV is so controlled that the radiator thermostats can always remain in their regulating range despite changing external conditions.
The external temperature TeXter al and the curve gradient H fed to the presetting means 1 are also continued to be used during daytime oper-ation to modify the desired value TS depending on the external con-ditions. This input of the summating point 2 does therefore not have to be necessarily constant throughout the day.
Claims (13)
1. A method of setting the mean value of the temperature at which a heating medium is supplied in a heating apparatus, heating the medium intermittently, of a heating system comprising at least one adjustable throttling point through which the heating medium passes, wherein a desired value for the supply temperature is determined on the basis of external factors influencing the degree of heating required and the heating medium is heated to the desired value of supply temperature with the at least one throttling point fully open, characterized in that a function representing the starting characteristic with which supply temperature changes with heating is determined, at least one parameter of the starting characteristic function is changed to form a desired characteristic function, and the desired value for supply temperature is changed until the progress of the heating has conformed to the desired characteristic function in each heating phase.
2. A method as claimed in claim 1, wherein the starting or desired characteristic function with which the supply temperature changes conforms to the following auxiliary function:
wherein:
T V (t) is the supply temperature, P K is the maximum heat output of the boiler, C m is the thermal capacity of the through-going heating medium, t is time, C k is the thermal capacity of the boiler, and T R is the return temperature of the heating medium.
wherein:
T V (t) is the supply temperature, P K is the maximum heat output of the boiler, C m is the thermal capacity of the through-going heating medium, t is time, C k is the thermal capacity of the boiler, and T R is the return temperature of the heating medium.
3. A method as claimed in claim 1, wherein the parameters of the starting characteristic function are determined by measuring the supply temperature at at least three instants in time.
4. A method as claimed in claim 2, wherein the desired characteristic function is formed from the starting characteristic function by changing the parameter C m.
5. A method as claimed in claim 4, wherein the desired characteristic function is formed by reducing the parameter C m.
6. A method as claimed in claim 5, wherein the parameter C m in the desired characteristic function is between approximately 20% and approximately 40% smaller than the parameter C m in the starting characteristic function.
7. A method according to claim 1, claim 2 or claim 3, wherein the starting characteristic function is determined during each transition from night-time operation to daytime operation.
8. A method as claimed in claim 1, claim 2 or claim 3, wherein a predetermined dead period is provided between determination of the starting characteristic function and forming of the desired characteristic function.
9. A method as claimed in claim 1, claim 2 or claim 3, wherein the difference between the changed desired supply temperature and the actual supply temperature value is used to form an input value for an integrator which switches the heating apparatus ON and OFF by means of a switch with a hysteresis characteristic.
10. A method as claimed in claim 9, wherein the threshold values for the hysteresis characteristic of the switch are determined from the parameters of the desired characteristic function.
11. Means for setting the mean value of the temperature at which a heating medium is supplied in a heating apparatus, heating the medium intermittently, of a heating system comprising at least one adjustable throttling point through which the heating medium passes and in which the heating medium is heated to the desired value of supply temperature with the at least one throttling point fully open, the means comprising:
means arranged to determine a desired value for the supply temperature on the basis of external factors influencing the degree of heating required, means arranged to determine a function representing the starting characteristic with which supply temperature changes with heating, means arranged to change at least one parameter of the starting characteristic function to form a desired characteristic function, and means to change the desired value for supply temperature until the progress of the heating has conformed to the desired characteristic function in each heating phase.
means arranged to determine a desired value for the supply temperature on the basis of external factors influencing the degree of heating required, means arranged to determine a function representing the starting characteristic with which supply temperature changes with heating, means arranged to change at least one parameter of the starting characteristic function to form a desired characteristic function, and means to change the desired value for supply temperature until the progress of the heating has conformed to the desired characteristic function in each heating phase.
12. Means for carrying out a method as claimed in any one of claims 1 to 3, the means comprising pre-setting means arranged to produce, as a result of external factors influencing the need for heating, a desired temperature value signal, an integrator arranged to be supplied with the difference between a modified desired supply temperature signal and an actual supply temperature value signal, a switch with a hysteresis characteristic arranged to produce a boiler control signal for switching the state of the heating apparatus when the integrator output signal exceeds a first predetemined value or falls below a second predetermined value, parameter identification means arranged to determine the parameters of the starting characteristic function, computing means arranged to calculate the desired characteristic function and form the difference between the desired characteristic function and the measured progress of heating of the heating medium, an error signal producing means to produce, in dependence on the desired charateristic function formed in the computing means, an error signal and, depending on the error signal, to produce at least two values of temperature signal of which at least one is a positive change and one is a negative change, and summing means arranged to add the values of the temperature signal every time the boiler is switched OFF, the output of the summing means being arranged to be added to the output of the pre-setting means to modify the desired temperature value signal.
13. Means as claimed in claim 12, wherein the error signal producing means is arranged to produce three values of temperature signal corresponding to a temperature change of -0.2°C., 0°C. and +0.2°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3838005.6 | 1988-11-09 | ||
| DE3838005A DE3838005A1 (en) | 1988-11-09 | 1988-11-09 | METHOD FOR ADJUSTING THE AVERAGE VALUE OF THE FLOW TEMPERATURE OF A HEATING MEDIUM AND CIRCUIT ARRANGEMENT FOR IMPLEMENTING THE METHOD |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2000867A1 CA2000867A1 (en) | 1990-05-09 |
| CA2000867C true CA2000867C (en) | 1999-01-12 |
Family
ID=6366817
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002000867A Expired - Fee Related CA2000867C (en) | 1988-11-09 | 1989-10-17 | Method of setting the mean value of the supply temperature of a heating medium and circuit for performing the method |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPH0827028B2 (en) |
| BE (1) | BE1002990A3 (en) |
| CA (1) | CA2000867C (en) |
| CH (1) | CH678887A5 (en) |
| DE (1) | DE3838005A1 (en) |
| DK (1) | DK168247B1 (en) |
| FI (1) | FI92105C (en) |
| FR (1) | FR2638864B1 (en) |
| GB (1) | GB2225653B (en) |
| IT (1) | IT1238526B (en) |
| NL (1) | NL192541C (en) |
| SE (1) | SE500088C2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT398832B (en) * | 1990-11-19 | 1995-02-27 | Vaillant Gmbh | CENTRAL HEATING SYSTEM |
| SE539644C2 (en) * | 2015-12-28 | 2017-10-24 | Nordomatic Ab | Method and system for regulating indoor temperature |
| FR3061268B1 (en) * | 2016-12-22 | 2022-05-13 | Commissariat Energie Atomique | METHOD FOR DETERMINING THE LOAD SHEDDING CAPACITY OF A BUILDING USING THERMAL INERTIA, ASSOCIATED LOAD SHEDDING METHOD AND SYSTEM IMPLEMENTING THE SAID METHODS |
| KR101997043B1 (en) * | 2017-12-26 | 2019-07-08 | 린나이코리아 주식회사 | Apparatus and method for heating temperature control of each control system using boiler return temperature |
| CN110894978B (en) * | 2019-04-10 | 2022-04-29 | 北京西门子西伯乐斯电子有限公司 | Air source heat pump heating system and controller and control method thereof |
| DE102021200129A1 (en) | 2021-01-08 | 2022-07-14 | Viessmann Climate Solutions Se | METHOD OF OPTIMIZING A HEATING CURVE AND HEATING SYSTEM |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4347974A (en) * | 1981-03-05 | 1982-09-07 | Honeywell, Inc. | Temperature control system with night setback programming as a function of temperature conditioning load |
| DE3202168A1 (en) * | 1982-01-25 | 1983-08-04 | Siemens AG, 1000 Berlin und 8000 München | Regulating device for a hot-water central heating system |
| NL8200316A (en) * | 1982-01-28 | 1983-08-16 | Willempje Johanna Dogger Lam | CENTRAL HEATING DEVICE. |
| DE3300082A1 (en) * | 1983-01-04 | 1984-07-05 | Centra-Bürkle GmbH & Co, 7036 Schönaich | Process and device for the optimisation of the heating curve of a heating plant |
| DE3345949A1 (en) * | 1983-12-20 | 1985-06-27 | Christian Prof.Dipl.-Ing. 7710 Donaueschingen Dirks | Apparatus for controlling a central heating system |
| EP0192227A3 (en) * | 1985-02-18 | 1987-06-24 | HAPPEL GmbH & Co. | Method for space temperature regulation |
| FR2599823B1 (en) * | 1986-06-06 | 1993-11-19 | Cie Generale D Electricite | METHOD AND DEVICE FOR CONTROLLING CENTRAL HEATING |
| FR2606177B1 (en) * | 1986-11-04 | 1989-04-14 | Coussement Bruno | METHOD FOR REGULATING THE TEMPERATURE OF A CENTRAL HEATING SYSTEM |
-
1988
- 1988-11-09 DE DE3838005A patent/DE3838005A1/en active Granted
-
1989
- 1989-10-16 CH CH3759/89A patent/CH678887A5/de not_active IP Right Cessation
- 1989-10-17 CA CA002000867A patent/CA2000867C/en not_active Expired - Fee Related
- 1989-10-25 SE SE8903551A patent/SE500088C2/en not_active IP Right Cessation
- 1989-10-30 DK DK539389A patent/DK168247B1/en not_active IP Right Cessation
- 1989-11-01 NL NL8902700A patent/NL192541C/en not_active IP Right Cessation
- 1989-11-08 FI FI895320A patent/FI92105C/en not_active IP Right Cessation
- 1989-11-08 IT IT67979A patent/IT1238526B/en active IP Right Grant
- 1989-11-08 GB GB8925250A patent/GB2225653B/en not_active Expired - Lifetime
- 1989-11-09 FR FR8914691A patent/FR2638864B1/en not_active Expired - Fee Related
- 1989-11-09 JP JP1292129A patent/JPH0827028B2/en not_active Expired - Lifetime
- 1989-11-09 BE BE8901196A patent/BE1002990A3/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| FR2638864B1 (en) | 1996-08-02 |
| IT8967979A1 (en) | 1991-05-08 |
| FI92105B (en) | 1994-06-15 |
| NL192541C (en) | 1997-09-02 |
| DK168247B1 (en) | 1994-02-28 |
| IT8967979A0 (en) | 1989-11-08 |
| JPH02183734A (en) | 1990-07-18 |
| IT1238526B (en) | 1993-08-18 |
| FI92105C (en) | 1994-09-26 |
| FR2638864A1 (en) | 1990-05-11 |
| SE8903551D0 (en) | 1989-10-25 |
| CA2000867A1 (en) | 1990-05-09 |
| GB2225653B (en) | 1992-12-23 |
| DK539389A (en) | 1990-05-10 |
| DE3838005A1 (en) | 1990-05-10 |
| JPH0827028B2 (en) | 1996-03-21 |
| SE500088C2 (en) | 1994-04-11 |
| DE3838005C2 (en) | 1991-12-05 |
| FI895320A0 (en) | 1989-11-08 |
| GB8925250D0 (en) | 1989-12-28 |
| GB2225653A (en) | 1990-06-06 |
| SE8903551L (en) | 1990-05-10 |
| BE1002990A3 (en) | 1991-10-15 |
| DK539389D0 (en) | 1989-10-30 |
| NL8902700A (en) | 1990-06-01 |
| NL192541B (en) | 1997-05-01 |
| CH678887A5 (en) | 1991-11-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA1244112A (en) | Means for setting the switching on and off periods of a burner of a hot water heating installation | |
| CA2249983C (en) | Method and device for temperature control of hot tap-water | |
| US6627858B2 (en) | Hot-water supply system | |
| EP1564616A2 (en) | System for independently regulating temperatures in different spaces and temperatures of one or more hot-water suplies | |
| US4844335A (en) | Microprocessor controlled heating system | |
| US4671457A (en) | Method and apparatus for controlling room temperature | |
| CN108474587B (en) | Boiler for heating and water heating and control method thereof | |
| CN111503903B (en) | Accurate constant temperature control system and control method for water heater | |
| US5655710A (en) | Method for controlling operated-units count of fluid heating units | |
| CA2000867C (en) | Method of setting the mean value of the supply temperature of a heating medium and circuit for performing the method | |
| US11221150B2 (en) | System and method of controlling a mixing valve of a heating system | |
| US20170328599A1 (en) | System and method of controlling a mixing valve of a heating system | |
| US5697551A (en) | Heating system of the type for apartments or offices in buildings | |
| US4156455A (en) | Method and apparatus for controlling a heat transfer installation | |
| EP0085466A1 (en) | Central heating system | |
| CN113405153A (en) | Control method and device for centralized cooling/heating system | |
| GB2113427A (en) | Central heating systems | |
| JP4582396B2 (en) | Water pump control system | |
| JP3947967B2 (en) | Electric water heater | |
| JPS61289266A (en) | Flow amount control of hot-water supplier | |
| JPS5920938B2 (en) | Control method for heat exchange equipment | |
| JPH0339228B2 (en) | ||
| JPS6186531A (en) | Control device for electric water heater | |
| SU1747808A1 (en) | Method of automatic water temperature control upstream of hot-water boiler | |
| SU974044A1 (en) | Apparatus for controlling heat consumption for central heating |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |