DE2939719A1 - Central heating fuel economy system - has heat-up time circulated from difference between internal and ambient temperatures - Google Patents

Abstract

The system economises fuel in a building central-heating system by cutting out heat-generation during slack periods and cutting it in again in sufficient time before demand resumes. Ambient temperature and also mean internal temperature are taken into account in determining the appropriate moment. The heat-up time is a function of the colling-down time elapsing after cut-out and also of the difference between internal and external temperatures, and of a constant. The latter is arrived at from a base value by measuring the actual time for heating-up and comparing it with the calculated value.

Description

The invention relates to a method for minimizing the Drenn-

consumption of a building heating system by switching off the heat generation and heating system during breaks in use and switching them on again in good time before the start of use, whether the outside temperature at this point in time as well as a knightly room temperature ces jeb £ iuJe3 taken into account: -ercen.

With building heating it is not necessary to save energy to avoid overheating only during occupancy, but also during the non-use of the same to lower the temperatures.

In order to meet the former requirement, it is known the heat generating plant by means of switching the burner on and off by a room thermostat control that responds to appropriately set temperature values. To fulfillment of the second requirement, it is known, a time-dependent temperature decrease to be carried out during the night, e.g. with a weather-compensated control system. the The mode of operation during night operation is such that despite the lowering phase heat is offered to the building. As soon as the timer switches to night mode, there is a reduction in the flow temperature that corresponds to the theoretical heat demand for the night setpoint at the current outside temperature. This The process takes place independently of the heat that is actually still in the building. Due to the constant supply of heat, the building cools more slowly and above all not as deep as possible.

The saving effect achieved here is far from optimal, because the entire system continues to run, the heat generation system with less Power, but the parts of the heating system that require energy, such as the circulation pumps, can continue to be operated, as well as the difference between the daily target temperature and Reduced temperature is relatively low. Since such devices usually have a timer own the heat generation system at one time, fixed at a fixed time switches back to normal operating load, it occurs in appropriate weather conditions overheating and the resulting loss is further diminished the less than optimal savings with this method of night setback.

c a further development of this older state of the art relates in addition, the mean indoor temperature to optimize the efficiency of the building heating with a. It is based on the knowledge that a minimum of energy consumption in the form of fuel and electrical energy is achieved when during the non-occupancy due to non-heating, the greatest possible depending on the circumstances The internal temperature is reduced and this results in the shortest possible heating-up period under full power of the building heating connects in such a way that at the beginning of the the subsequent occupancy time the daily setpoint is just reached. The implementation optimization takes place here in such a way that at the end of the occupancy of the building on one the lower temperature limit value, e.g. the dew point in the building's outer walls is equivalent to. Should this limit be reached due to extremely low outside temperatures or if the building is not used for several days, the is switched on again Heating at full power until the room temperature is a few degrees above this The limit value has risen and then switched off again. There is thus a automatic control, so that the lower temperature limit until the next heating-up period is not fallen below.

The optimal switch-on time for the next heating-up period is determined by comparing two measurements with programmed quantities as follows. The building is cooled down by measuring the drop in the mean room temperature determined and from this the energy consumption required for heating is determined. The measurement of the outside temperature results in the amount of energy required for this expenditure Capacity. These measured quantities are now compared with programmed quantities, and as a result, the switch-on time is determined.

Establishing these programmed values according to the state of the art is now very cumbersome, due to numerous factors that cannot be properly determined dependent and thus imprecise, so that inevitably the optimal time for restarting the heater is not found at full power. This is upon it due to that the programmed values are more empirically based on average values of the heating-up period as they are in spring, autumn and average winter conditions and also the most severe winter conditions occur and factors also come into play here, such as the response time of the heating system, heat storage properties of the building, Length of the shutdown period, wind strength, temperature and their changes during the shutdown period, extended operating time of the system during the previous one Occupancy time, etc.

The invention is now based on the object of creating a method by means of this a continuous and automatic calculation of the minimum heating time with full power to the daily target value at the beginning of the occupancy period, based on of the greatest possible reduced temperature, is made possible without the setting of building parameters.

According to the invention, this object is achieved in a characteristic manner solved that additionally the time elapsed since switching off, the cooling time tab, for the calculation of the heating time tauf according to the equation T. - T auf 1 a ab auf (i a) ab is taken into account, and that the constant K of a fundamental value by measuring the actually required heating time and comparing it with the calculated value is automatically corrected.

According to a further development according to the invention, one proceeds in such a way that that an extension of t to causes changes in K with the full value, only a fraction of the changes in K that cause a shortening of t so determined new value of K enter and that in the program memory upper and lower limit values for the value of K have been entered so that they cannot be lost.

According to a further embodiment of the invention, one proceeds such that when an adjustable minimum internal temperature Tmin is reached before the start the heating-up time at intervals to maintain this value switched on with a switching differential that depends on the duration of the optimization phase and that when this value is reached, the before this point in time last heating time t calculated according to the equation to only changes the outside temperature Ta is influenced.

Due to the automatic correction of the constant according to the invention K and the calculation of the heating time, taking into account the cooling time according to the invention the advantage of an adaptive mode of operation, so that after a certain operating time the optimal and all influences of the building and the system comprehensivetufheiz}; curve is determined automatically.

According to a further embodiment according to the invention, the procedure is as follows: that the full power of the heat generation system is used for heating, with the proviso that during the heating period to quickly reach about the Licensing medium end temperature through adjustable, pulsed opening of the mixing valve the amount of electrical medium supplied to the heat generation system to the extent of zero is increased to the full value, such as the adaptation to that of the heat generation system The amount of heat supplied requires it. Only with a sufficiently high flow temperature the heat generation system can have very low levels, especially at the start of heating The return temperature can be raised by adding the flow rate to such an extent that it falls below the immersion gas dew point temperature is avoidable.

The subject matter of the invention is hereinafter referred to as DezugnaIinte, for example explained on the attached block diagram.

As evidenced by this block diagram, the entire control takes place by a microcomputer 1, which has a microprocessor 2, all of the control and arithmetic functions executes, a data memory 3 with direct access for the storage of current Data, such as times of the beginning and end of occupancy and interim results, as well as a program memory 4 has a read-only memory or read-only memory. The program memory 4 contains all commands and data that are required to the microprocessor 2 for carrying out the calculations and for controlling the processes to cause.

The microcomputer 1 with the associated ones is connected via two input / output modules 5 Components connected. Here are connected in detail.

1. Display 6 for display and keypad 7 through which all for the user important data such as occupancy periods and target temperatures via a keyboard entered and displayed.

2. An analog-to-digital converter 8, which via a measuring point switch, controllable by the computer, switched to outside or inside temperature sensors can, whereby the microcomputer 1 digitally measure the inside and outside temperature accurately can.

3. An electronic clock 9 from which the microcomputer 1 shows the time of day and can read in the day of the week.

4. Two input amplifiers 10, which receive the signals from the outside and inside temperature sensors amplify loa and forward to the measuring point switch 10b, a switching amplifier 11 and Rclais 12, through which the heating system can be controlled, the Burner 12c on and off, the actuators 12b, e.g.

Mixing valves that can be opened and closed and a switchover on temperature control, e.g. with a weather-compensated controller 12a or adaptive Can take effect.

The method according to the invention is described below using an exemplary embodiment explained.

Using the equation characteristic of the method according to the invention the minimum heating time is continuously tauf under after specifying a value for K Consideration of the respectively determined values of the inside temperature T and outside temperature T a and the time tab that has elapsed since switching off is calculated, e.g. every 15 minutes a value for t is determined.

on The automatic correction of the constant K in the adaptive mode of action, called the optimization phase for short, begins at the end of the occupancy period. To this The point in time is the next beginning of the occupancy period from the data memory determined and the duration of the optimization phase is calculated. Then one follows Trial calculation of the heating-up time with a preset from the program memory Cool down time of 2 hours, what for the temperature reduction represents a suitable minimum value, the normal temperature TN and the measured outside temperature Ta If it is found here that the sum t to + 2 h> topt, will the temperature decrease is suppressed and the system continues to be controlled by the weather controller regulated. This trial calculation is of importance near and particularly below the design temperature of the heating and heat generation system, there in this outside temperature range the reheating of the building with the available Heating output is not assured, e.g. under the conditions of an extremely low Outside temperature with additional cooling factors as shown.

As soon as the temperature reduction is released after the above sample calculation is, the microcomputer controls the corresponding actuators in such a way that the Burner switched off, the circulation pump switched off and the mixing valve closed will. As explained above, the Value of the heating time tauf 'whereby at the same time the internal temperature to that effect it is monitored that a minimum value Tmin is not undershot. The internal temperature remains T above the minimum temperature T, ain, until the calculated heating time meets the condition tauf + tab> topt fulfilled, heating begins.

The MikrorecIner now controls the corresponding actuators in such a way that that the burner is switched on, the circulation pump switched on and the mixing valve adjustable pulse-wise opened.

This successive opening process requires constant full burner output, that the flow temperature rises relatively quickly, which is with a reduced flow rate of the heating medium leads to faster heating due to the increased temperature gradient leads to a correspondingly lower temperature gradient than if with a larger flow rate is present.

At the same time as this process is the time ts, the actual internal temperature T. and the actual outside temperature Tas are saved for further processing. The heat generation and heating system then works until the internal temperature Ti is the setpoint T has reached N, i.e. the normal temperature of the Occupancy is available. This is the time at which the optimization phase actually ends. The associated time te is also saved and the microcomputer switches the mixing valve on controller operation. The regulation now takes place during the occupancy period via the weather controller.

The adaptive mode of operation is achieved by the fact that after each optimization phase calculated with the value of the building diagnosis number Kn retrieved from the data memory Heating time t is compared with the result obtained. The previously determined and cached values Tis, TasI t and te 5 from the beginning or from the end of the heating operation, where tests = tauf The new value determined in this way K +1 always corresponds to the current status and is on the safe side, because one Extension of to causing changes in K with the full value, a shortening Changes from K to 80t are only included in Kn + 1. In other words, if the heating process took too long compared to the calculated value, will the value K n is reduced to Kn + 1, so that due to the inversely proportional Ratio the next heating time is extended, and vice versa. In The upper and lower limit values for K are still captive in the program memory entered.

When the system is started up for the first time, the program memory a K-value Ko is given as the smallest initial value, which leads to an intentional too leads to a long heating-up time, with automatic due to the described adaptive function after a few days, K is increased to a building-specific value K n. The same applies to a power failure of more than 70 hours, since then the for The batteries designed for this backup period are exhausted and the corresponding batteries data stored in the microcomputer are deleted.

If now during the optimization phase the internal temperature reaches the minimum value Tmin must be reduced to avoid excessive cooling and condensation use intermediate heating in the building. There is then a heater in the same Way as with the heating process, which is necessary to achieve the Normal temperature at the beginning of the occupancy period. This results within The minimum temperature is exceeded in the shortest possible time.

At the same time, the value t ab at the start of intermediate heating for the Recalculation of K cached. The intermediate heating ends as soon as the internal temperature has risen exceeds the value T. = Tmin + XSd.

After passing through the switching differential XSd, a switch is made to the same way as at the time of lowering the internal temperature at the end of the Occupancy. The microcomputer is then located again until the next time it is reached a minimum temperature value in the optimization phase.

In order to reduce the switching frequency of this timing control, their switching differential adapted to the duration of the optimization phase and Sd for longer Periods switched to a larger value as follows: XSd = 0.5 K at topt < 16h XSd = 3 K if topt> 16h If within the last two hours of the occupancy the measured internal temperature by more than 2 K above the setpoint for at least 0.5 h TN rises, the temperature will drop after the tripping time of 0.5 h has elapsed initiated ahead of schedule. The setpoint for the minimum internal temperature is until programmed end of occupancy the normal temperature T, only then takes place the switchover to the minimum temperature Tmin of the optimization phase. Through this is in the case of a non-representative increase in the internal temperature and / or an outside temperature drop during this time prevents an incompatible cooling.

The requirement arises particularly in the case of district heating supply a decreasing load on the networks due to heating processes when the outside temperature falls, so that the peripheral heat consumers still have sufficient heating power To be able to provide. Under these conditions the temperature decrease suppress even at relatively high outside temperatures, and this fact becomes thereby taken into account that the respective value K with a corresponding factor is multiplied by less than 1 in order to lengthen the value for tauf accordingly.

Claims (4)

Method for minimizing the fuel consumption of a building heating system Claims (1 method for minimizing the fuel consumption of a building heating system by switching off the heat generation and heating system during breaks in use and reactivation of the same in good time before the start of use, whereby to determine at this point in time the outside temperature and the mean inside temperature of the building are taken into account1 by noting that additionally the since Switching off the elapsed time, the cooling time tabl for calculating the heating-up time tauf according to the equation Ti - Ta tauf K- (Ti-Ta) - tab 1 a is taken into account, and that the constant K is calculated from a basic value by measuring the actually required The heating time and comparison with the calculated value is automatically corrected. 2. The method according to claim 1, characterized in that g e k e n n z e i c h n e t, that an extension of t to causes changes in K with the full value, a shortening of the changes effecting only a fraction in the so determined new value of K enter and that in the program memory upper and lower limit values for the value of K have been entered so that they cannot be lost. 3. The method according to claim 1, characterized in that g e k e n n z e ic h n e t, that when an adjustable minimum internal temperature Tmin is reached before the start of the Heating time tauf to maintain this Worth the facilities at intervals with a switching differential that depends on the duration of the optimization phase be clialtet, and that when this value is reached, those before this point in time Finally, the heating time tauf calculated according to the equation only depends on changes in the Outside temperature Ta is influenced. a 4. The method according to claims 1 and 2, characterized g e k e n n -z e i c h n e t that the full power of the heat generation system is used for heating is, with the proviso that during the heating period by adjustable in pulses Activation delays the opening of the mixing valve and so that of the heat generation system supplied amount of the heating medium cooled to room temperature in the amount of Zero is increased to the final value, as is the change in the differential temperature between return and flow of the heat generation system it requires.