NL8303277A - HOT WATER HEATING INSTALLATION. - Google Patents

Description

"N.0. 32037" *

Hot water heating system.

The invention relates to a hot water heating system with a heat generator, circulation pump and heating bodies controlled by thermostat valves 5, wherein the supply temperature can be changed.

In known installations of this kind, changes in the supply temperature, such as can be obtained by changing the boiler temperature, by adjusting a mixing valve or the like, take place manually, time-dependent or weather-dependent. Within each individual room or room, the heat output is controlled by the thermostatic valves depending on actual needs. When the need for heat decreases in a room, the thermostat associated with this room closes. A smaller amount of hot water flows through the associated heating bodies, which cools more during the lead time. As a result, the logarithmic average temperature of the heating body, which determines the heat output, decreases. At the same time, the arithmetic mean temperature, which determines the heat loss in the pipelines, also changes, although not to the same extent as the logarithmic mean temperature. Therefore, the heat loss increases as a percentage of the heat output delivered and the effect of the heating system decreases.

When the return temperature assumes too high values with a condensing boiler, as is the case with the same supply temperature and strong load, it can no longer cause condensation in the boiler and therefore does not absorb condensation heat. This also affects the efficiency or effect of the heating installation.

The object of the invention is to indicate a hot water heating installation of the type described in the preamble, which makes it possible to reduce demand-dependent losses in efficiency of the installation.

This object is fulfilled according to the invention by means of a controller which is influenced by the supply and return temperatures and which changes the supply temperature such that the difference between the supply and return temperature is kept at a predetermined nominal value.

With this version, the flow temperature is controlled depending on the load of the Installation. The return temperature, which the flow temperature depends on, can be regarded as an expression of the load on the installation. Within the system there is therefore a feedback that makes it possible to make the flow temperature dependent on the load.

In addition, the advantage arises that the relationship between the running and the return temperature within wide limits can be chosen arbitrarily. Therefore, depending on the nominal value, depending on the tax, influence on the yield-reducing factors can be taken, as will be explained below.

10 In the simplest case, the nominal value is constant. This leads to the supply temperature decreasing together with the return temperature. This causes a decrease in the arithmetic average temperature and, therefore, a decrease in the heat loss in the pipelines. However, the situation is particularly advantageous when the nominal value as a function of the return temperature is predetermined. Then arbitrary relationships between the supply temperature and the return temperature can be obtained. It is advantageous here if the nominal value increases with an increasing return temperature, and in particular increases linearly. This gives the smallest possible arithmetic mean temperature in the pipelines and therefore the least loss of heat. Since the nominal value here becomes approximately directly proportional to the load on the installation, it is optimally obtained that the roundly pumped water quantity is approximately constant. This gives the further advantage that the P deviation of the thermostat valves is also approximately constant.

In one embodiment, it is ensured that the nominal value is constant under a limit value of the return temperature. This takes into account the fact that at low return temperatures, the nominal value may become too small to provide a useful control.

Another possibility lies in the fact that the nominal value with increasing return temperature first decreases to a lower limit value and then increases again. This measure is preferred when a uniform start-up is desired when starting up a cold installation until normal operation is reached. In particular, the controller can be designed such that the flow temperature is kept constant below the limit value of the return temperature.

The variation of the nominal value can also be chosen 40 so that particularly good heat transfer conditions in the heating • - - A -7 “7 -“ · «-» »

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3 boiler or in the heat pump. It is important here that the return temperature is as low as possible. This can hereby be realized that the nominal value above a predetermined return temperature increases sharply. Particularly when a condensing boiler is used, it is preferable if the nominal value, when the return temperature approaches the condensation temperature from below, increases such that the return temperature does not exceed a limit temperature below the condensation temperature. It is therefore always ensured that the return water can absorb condensation heat 10.

In practice, a variation or more of the nominal value can be indicated that on the one hand keeps pipeline losses small (in the lower and middle area of the load) and in addition, keeps the return temperature low (in the middle and upper range of the load). . An optimization may have to be done in the overlapping areas.

In an installation with back-mixing pipe and a valve influencing the mixing behavior, the controller for controlling the nominal temperature difference can control the valve. It is then possible to use a conventional construction of the installation and it is only necessary to change the type of control of the valve.

In particular, the back-mixing line can have a throttling location and the valve can be included between the heat generator and the back-mixing line.

In this way one only needs a simple two-way valve.

In an installation with a heat generator heating device, the heat output of which can be changed, the controller for holding the nominal value of temperature difference can control the heat generator heating device. Here, too, a conventional installation can be used, in which only the control of the heating device is changed.

In an exemplary embodiment, an electronic temperature difference controller is used, which is connected via lines carrying electrical signals to a flow temperature sensor and a flow temperature sensor. Such an electronic controller has the advantage that even further dependencies can be introduced without great problems, for instance a control of an upper limit for the supply temperature in dependence on the outside temperature.

In another exemplary embodiment, a differential thermostat with two opposing working elements, each of which is connected to a system f - * - --9 * * 4, is connected to a system f - * - --9 * * 4 with a flow and return temperature sensor. Such a regulator has a very simple structure and is independent of the electrical network.

In particular, the differential thermostat may be fitted in place of a heat generator thermostat and a switch for turning the heat generator heating on and off can energize. The desired control dependence can therefore be obtained by simply replacing the thermostat.

It is also advantageous if the differential thermostat is mounted on the valve as an attachment and energizes the keep. Since such valves are often provided with a detachable attachment, the intended result can be obtained by using this special differential thermostat attachment.

The systems preferably have a liquid-vapor filling and the nominal value of the temperature difference is determined by temperature and position-dependent forces of the two working elements. Due to a suitable combination of filling media, pressure-bearing surfaces of the working elements, efforts and characteristics of the springs and resilient working elements used, equilibrium positions are defined which are defined by a return temperature-dependent nominal value.

In a preferred embodiment it is ensured that the pressure surfaces of the working elements are equal and the vapor pressure curve of the liquid-vapor filling of the system associated with the return temperature is above that of the system associated with the supply temperature. The construction of the working elements can therefore be done rationally in a rational manner. The equally large working elements can be installed to save space. Fen compensation spring can be omitted if necessary.

In many cases it has the advantage if the controller keeps the supply temperature constant in a lower region of the return temperature and in an upper region of the return temperature keeps the temperature difference at the nominal value. In this way it is realized that the stated control is switched off at low heat demand, so that a certain minimum value of the supply temperature is maintained. Therefore, a subsequent increase in the heat requirement can be met quickly.

Structurally, this can be achieved, for example, by means that the working element of the system associated with the return temperature is fixed and the working element of the system associated with the return temperature is connected via a compression spring to the actuating element, that the compression spring is bridged by a force-locking coupling. «5 is when the pre-tensioning force of the compression spring has been overcome, and that both working elements have a resilient design.

In a further embodiment, it is ensured that the two working elements are formed by two set-up caps with ger-corrugated-tube bellows arranged therein and that a support extends between the facing bellows bottoms, which radially outwardly extends between the caps protruding, which runs axially along the outside of a cap and radially inwardly guided on the other side of this cap, acts on the closing piece. This provides a particularly simple and space-saving construction.

In particular, the support can be tubular and lie against the bellows bottom of the system associated with the supply temperature and guide the compression spring in its interior which extends between a transverse wall of the support and the other bellows bottom. The height dimension of this device is only slightly greater than the sum of the heights of both caps.

Furthermore, the pre-flow sensor with a heating device can be provided for obtaining an overnight reduction. This possibility, which is known per se, can therefore also be applied to the intended control.

The above term "heat generator" should cover all types of heat generation, so not only boilers but also, for example, heat pumps in which the heat in the boiler can be transferred directly, via a heat exchanger, via a condenser or the like, to the water of the heating installation turn into.

The invention will be elucidated on the basis of some exemplary embodiments with reference to the drawings, in which:

Fig. 1 shows the diagram of a hot water heating installation according to the invention; FIG. 2 shows a temperature diagram;

Fig. 3 shows the schematic of a modified embodiment;

Fig. 4 shows the schematic of a third embodiment;

Fig. 5 shows the embodiment of FIG. 4 in constructional form;

Fig. 6 shows a diagram of the dependence between the nominal value and the return temperature; and

Fig. 7 shows a corresponding diagram of another dependence between nominal value and return temperature.

The hot water heating installation of Fig. 1 has a boiler 1, the outlet 2 of which is connected via a three-way mixing valve 3 to the supply line 5 in which a circulation pump 4 is included. The said 6 pipe leads to a plurality of heating elements 6, 6a, 6b connected in parallel, to which a thermostat valve 7, 7a and 7b is each connected. The common return line 8 is connected on the one hand to the boiler inlet 9 and on the other hand to a back-mixing line 10 which leads 5 to the three-way valve 3.

Temperature signals from a flow temperature sensor 12 are supplied to an electronic controller 11 via a signal line 13 and from a return temperature sensor 14 via a signal line 15. A nominal value for the difference between the flow temperature and the return temperature is determined by means of a nominal value setting device 16. The setting of the nominal value can be done manually, but in particular depends on the return temperature. Apart from the setting of the nominal value, further influence may also be provided, for example the determination of an upper limit value for the supply temperature. If necessary, this maximum permitted flow temperature can be controlled depending on the outside temperature. An actuator 18 for the three-way valve 3 is controlled via a further signal line 17.

Fig. 2 shows the supply temperature and the return teraerature tr which are both measured in the vicinity of the heating body. As a dot line, the average temperature is t ^. of the pipelines, i.e. the arithmetic mean of the temperature of the supply line and the temperature of the return line. As a dashed line, the average temperature t ^ on the heating bodies, i.e. the logarithmic average value between the supply temperature and the discharge temperature, is indicated. The state a represents the output position in which the difference between the flow temperature and the return temperature is equal to the nominal value S] _. The average temperature t of the heating body is only slightly below the average temperature tm of the pipeline since the arithmetic mean temperature approaches the logarithmic mean temperature due to the relatively large amounts of hot water circulated. The state b indicates the corresponding temperatures when a higher heat demand has arisen but no flow temperature control according to the invention occurs. The thermostat valve throttles and the flow rate hero decreases. As a result, the two average temperatures tmr and ^ as well as the return temperature tr decrease. It should be taken into account that as a result of the slower flow there is a considerable cooling in the heating body and that the average temperature - 1 1 · · \ · 7 duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk duidelijk h h h by the pipeline. lies. The state c shows the position with reduced heat demand, but with a flow temperature control. As a result of the decrease of the return temperature tr, the nominal value S2 is also somewhat reduced. For the heat requirement, which corresponds to the heating body average temperature t ^ as in the state b, the supply temperature is considerably smaller and the return temperature higher. As a result, the average temperature tjuj. of the pipeline is only slightly above the average temperature t ^ of the heating body. The heat loss in the pipelines is therefore correspondingly low. The table below shows temperatures in ° C, as these can occur with the three states mentioned: 15 _a_b_c_ tv 90 90 60 tr 70 34 50 S 20-10 W 80 62 55 20 t ^ 79 54 54

In the embodiment of FIG. 3, reference numerals increased by 100 are used for equal parts. A back-mixing line is missing here. The setting of the flow temperature is changed by a corresponding control of the boiler heating device 19, represented by an oil burner. For this purpose, a switch 23 is included in the electrical supply lines 20 and 21 to the burner motor 22, which is actuated by a controller 111 in the form of a differential thermostat. The movable contact of the switch sits on a rod 24 on which two mutually opposing working elements 25 and 26 as well as a compensation spring 27 engage.

The working element 25 communicates via a capillary pipeline 113 with a supply temperature sensor 112 measuring the temperature of the boiler water. The system 28 thus formed has a liquid vapor filling. The other working element 26 communicates via a capillary tube 115 with a return temperature sensor 114. The system 29 thus formed also has a liquid vapor filling. In the present case, both systems have the same filling. When the return temperature increases due to a higher heat demand, the pressure in the working element 26 increases. The switch 23 is closed for so long. * -1 _______ sö 8 until the boiler temperature has increased to a value sufficient to open switch 23 again.

In the embodiment of Figs. 4 and 5, reference numerals increased by 200 for corresponding parts are used. In this case, a throttling location 30 is provided in the back-mixing line 210 and a valve 31 in the outlet line 202. When the closing piece 32 thereof is adjusted, the dividing ratio of the water supplied via the boiler 201 to the water supplied via the back-mixing line 210 changes, and thus the supply temperature, in the lead water. The working element 225 associated with the lead-in temperature has a cap 33 and a corrugated-tube bellows 34 fitted therein, the bottom 35 of which is connected via a support 36 to the closing piece 32. The return-temperature element 226 has a cap 37 and a cap therein fitted corrugated tube bellows 38, the bottom 39 of which is provided with a stop element 40. A compression spring 41 extends between support 36 and stop element 40. When compressed to a predetermined value, it is bridged by a force-coupling 42. Both corrugated tube bellows 34 and 38 have a resilient characteristic.

In this case, again both systems 228 and 229 are provided with a liquid vapor filling. However, the filling of the system 229 associated with the return temperature has a vapor pressure curve that is above that of the system 228 associated with the return temperature. With a small heat requirement, the pressure in the working element 225 predominates. The bottom 39 is located near its lower end position. The valve 31 is actuated in the sense of keeping the supply temperature constant, the value being given approximately by the bias of the spring 41. However, as the return temperature increases due to a greater heat demand, the pressure in the working element 226 eventually becomes so great that the spring 41 compresses and the force-closing coupling 42 closes. As a result, a regulation arises depending on the difference between the supply temperature and the return temperature. The difference value is determined both by the spring characteristics of the two corrugated tube bellows 34 and 38 and by the temperature-dependent forces of the working elements. Furthermore, an element can be built in, for instance in the form of a weight lever, whereby the resulting force-balance and the difference value can be changed.

As shown in Fig. 5, the valve 31 has a valve housing 43 of conventional construction and an attachment 44, which contains the regulator configured as differential thermostat 40. Both working elements 225 and 226 are in ^ - »-s -J *? 9 houses a housing 45, which can be placed on the valve housing 43 with the aid of a clamping device 46. The support 36 is tubular and accommodates the compression spring 41, which extends between a transverse wall 53 of the support 36 and the bellows bottom 39. A carrier 47 is provided on the support 36, which has a radially outwardly extending part 48, an axially outwardly extending part 48a and a radially inwardly extending part 49. This acts on a pin 50 to actuate the closure 32. The driver 47 is guided in the housing 45.

The flow temperature sensor 212 is associated with a heating device 51, which can be powered by current via a cable 52. This produces a nightly reduction.

In Fig. 6 a diagram shows the dependence of the nominal value S on the return temperature tr. In a lower region up to a limit value located at about 35 ° C, the temperature difference is constant, namely 5 ° C. As the return flow rate increases, the nominal value S increases approximately linearly.

In another device, such as the diagram of Figure 7, which indicates, the flow temperature ty is kept constant up to a return temperature of 40 ° C. That is, the temperature difference indicated by the nominal value S decreases linearly. A linear increase of the nominal value S then occurs with an increasing return temperature, i.e. an increasing load.

In the installations described, the real load, that is, the load registered by the heating body thermostats, determines the temperatures in the installation via the controller. Extra heat, such as, for example, from solar radiation, stored heat in building parts, and the like, which influence the load, is automatically taken into account when determining the flow temperature.

30 The nominal value S is set for each installation in such a way that optimum conditions with regard to heat loss occur. Usable values are between 5 ° C and 30 ° C. Favorable control ratios occurred when S = * 20 ° C at 100% load and decreased linearly with load behavior. The curves of FIGS. 6 and 7 are such that sufficiently high flow temperatures are still present in the lower loading area and the pipeline losses in the middle loading area are kept as small as possible. When it comes to keeping the return temperature under high load low, the S characteristic starting with the return temperature limit region 40 can be even steeper, as indicated,> '* * “·. ··' 7 * · '* ? Have 10.

A heat pump can also be used instead of the indicated boiler 1.

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Claims (22)

1. Hot water heating system with heat generator, circulation pump and heating elements controlled by thermostatic valves, whereby the flow temperature can be changed, characterized by a 5 regulator (11; 111; 211) which is influenced by the flow and return temperatures and which changes the flow temperature that the difference between the flow temperature and the return temperature is maintained at a given nominal value (S). Hot water heating system according to claim 1, characterized in that the nominal value (S) is given as a function of the return temperature. Hot water heating system according to Claim 2, characterized in that the nominal value (S) increases as the return temperature increases. Hot water heating system according to Claim 3, characterized in that the nominal value (S) increases linearly as the return temperature increases. Hot water heating system according to claim 3 or 4, characterized in that the nominal value (S) is constant below a limit value of the return temperature. Hot water heating system according to one of Claims 2 to 4, characterized in that the nominal value (S) first decreases to a lower limit value and then increases again as the return temperature increases. Hot water heating system according to one of Claims 1 to 6, characterized in that when a condensing boiler is used, the nominal value (S), as the return temperature approaches the condensation temperature from below, increases so much that the return temperature falls below the condensation temperature does not exceed the limit temperature 30. Hot water heating system with back-mixing pipe and a valve influencing the mixing behavior according to one of claims 1 to 7, characterized in that the controller (11, 211) for maintaining the nominal value (S) of the temperature difference is the valve (3 31) 35 steers. Hot water heating system according to claim 8, characterized in that the back-mixing line (210) has a throttling location (30) and that the valve (31) is arranged between the heat generator (201) and the back-mixing line. Warrawater heating system provided with a heat generator heating device, the heating power of which can be changed, according to any one of claims 1 to 7, characterized in that the controller (111) for maintaining the nominal value (S) of the temperature difference controls the heat generator heating device (19) 5. Hot water heating system according to one of Claims 1 to 10, characterized in that an electronic temperature difference controller (11) is used, which is connected via lines (13, 15) carrying electrical signals to a flow and return temperature. 10 temperature probe (12, 14). Hot water heating system according to one of Claims 1 to 10, characterized in that a differential thermostat with two opposing working elements (25, 26; 225, 226) is used as the controller (111; 211), each of which has a flow and return temperature sensors (112, 114; 212, 214) are connected to a system (28, 29; 228, 229). Hot water heating system according to Claims 10 and 12, characterized in that the differential thermostat (111) is arranged instead of a heat generator thermostat and a switch (23) for switching the heat generator heating on and off. Hot water heating system according to claim 8 or 9 and 12, characterized in that the differential thermostat is mounted as an attachment (44) on the valve body (43) and actuates the closing piece (32) thereof. Hot water heating system according to any one of claims 12 to 14, characterized in that the systems (28, 29; 228, 229) have a liquid vapor filling and the nominal value (S) of the temperature difference due to temperature and position-dependent forces of the two working elements (25, 26; 225, 226) has been determined. Hot water heating system according to claim 15, characterized in that the pressure surfaces of the working elements are equal, but the vapor pressure curve of the liquid vapor filling of the system (229) associated with the return temperature is higher than that of the system associated with the supply temperature (228). Hot-water heating system according to one of Claims 1 to 16, characterized in that the controller (211) has an approximately constant flow temperature in a lower region of the return temperature and, in an area above the return temperature, the temperature difference at the nominal value (S ). Hot water heating system according to one of Claims 12 to 16 and Claim 13, characterized in that the working element (225) of the system (228) associated with the supply temperature is fixed and the working element (226) of the system associated with the return temperature. system (229) are connected to the actuating element (36) via a compression spring (41), that the compression spring is bridged by a force-locking coupling (42) when the preload force of the compression spring is overcome, and that both working elements are resilient . Hot water heating system according to one of Claims 14 to 18, characterized in that the two working elements (225, 226) are guided by two plug-in caps (33, 37) with corrugated tube bellows (34, 38) arranged therein. and that between the facing bellows bottoms (35, 39) a support (36) extends which extends radially outwardly between the caps, axially extending along the outside of a cap and radially inwardly beyond this cap 15 padded carrier (47) acts on the closing piece (32). Hot water heating system according to Claims 18 and 19, characterized in that the support (36) is tubular, lies against the bellows bottom (35) of the system (228) associated with the supply temperature and in its interior the compression spring (41) which extends between a transverse wall (53) of the support and the other bellows bottom (39). Hot water heating system according to any one of claims 1 to 20, characterized in that the flow temperature sensor (212) is provided with a heating device (51) for obtaining a night-time draw. 25 Mil H-l · * t / --- - _ »*«