GB1571475A

GB1571475A - Circulating water heating system

Info

Publication number: GB1571475A
Application number: GB10400/78A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1977-03-17
Filing date: 1978-03-16
Publication date: 1980-07-16
Also published as: FR2384212A1; FR2384212B3

Description

(54) CIRCULATING WATER HEATING SYSTEM (71) We, ROBERTBOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1. l;CtlCls ellllblit of ( ;erni;iiiv do whereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:: The present invention relates to a circulating water heating system having two energy sources a heat accumulator which can be charged by the two energy sources, and a heat pump which can be connected to pump heat from the two energy sources or the heat iccumulitor into the heating net- work, and which can also be directly connected to at least one energy source or to the heat accumulator.

An object of the invention is to construct a device of the kind mentioned so that a greatest possible economical operation of the heating system is ensured. For this purpose. the device should discover, under the given meteorological conditions and dependent on the state variables within the system. the most favourable operational state with regard to costs in each case and bring this into being by appropriate switching of valves, pumps. fans. the heat pump and. where necessarv, an additional heating unit.

There is provided by the present invention a circulating water heating system, having a circulating water network and comprising a heat consuming device, two energy sources, a heat accumulator which can be charged by the two energy sources, a heat pump, the system providing means to connect at least one of the energy sources and/or the heat accumulator directly to said network. and to connect the heat pump to pump heat from the two energy sources and/or the heat accumulator into the circulating water network. and a regulator for regulating the circulating water temperature, wherein the regulator comprises a circulator which compares signals indicative of the temperatures of the heat sources and the heat accumulator in accordance with a predetermined reading schema both with one another as well as with a signal indicative of the circulating water temperature or the consuming device, and determines therefrom the mode of operation of the components of the system to provide the most favourable mode in any given circumstances with regard to economy of operation and to actuate said means accordingly.

The two heat sources may be a solar collector and an environmental heat exchanger, the former being the one which at least can be connected by said means directly to said network; and in this case, preferably the regulator controls the supply of heat to the circulating water network in at least two stages by determination of the deviation, if any, of the required temperature of the circulating water from the actual temperature thereof.

The calculator may use digital techniques.

This, however, is relatively expensive and can, because of the multiple connection of its switching elements, be adapted to different programmes only at great cost.

In a preferred embodiment of the invention the regulator can be adapted in a simple manner to different programs or different external conditions, under which the heating system must operate, without great cost.

In this embodiment, the calculator compfls- es outputs for respective operating modes of the system, and decision stations by which an operating signal is routed to a respective output according to the temperature indications provided by the input signals to the regulator, and relay change-over switches are associated with the decision stations of the regulator and the switching contacts of the relay change-over switches are supplied by a constant voltage source, and the excitation coils of the relay change-over switches are each actuated by means of a bridge circuit comprising a temperature probe pair, of the respective decision station.

The excitition coils of the relay changeover switches aun be connect, advan tcigeously in series, with an )l'erational amplifier anri with potentiometers for the purpose oi adjusting the switching hystcrcses of the change-over switches, in the diagonal 'irn0 of the bridge circuit.

A potentiometer is provided advan- tageously iil which bridge circuit lo adjust the switching, threshold and its adjustable tip is conneeled lo the one pole of the bridge voltage source. whilst its two terminal ends are each connected to one of the two temperature probes. whose other connec- lion ends ale connected t() the second pole of the hli(lge voltage source.

Hatch relay chinge-over switch may be nctuatetl by its own temperature probe in a bridge circuit. For this purpose (lilferential temperature regulators are suitable which cm already be obtained commercially in solar techniques. In this solution, under circumstances. however, many temperature probes are required and can be combined advantageously in a bundle.

The number of temperiture probes can be reduced, it i single temperature probe, constructed as a temperature-dependent resistor. is used at each place temperature is to be measured and its signal is used to adjust respective variable resistors of the indi vidual decision stations, whereby the variable resistors act as temperiture probes.

A direct current motor in the diagonal arm of a bridge circuit can serve advantageously to transmit the signal of a temper ature probe to the variable resistors by connection to the movable taps of the variable resistors and of a reference resistor located in the bridge circuit so as again to balance the bridge.

A simpler and thus particularly preferred solution is obtained when a single temperature probe is used at each temperature place. and a switching device is provided which operates automatically and forms, according to the reading sequence of the regulator. in running sequence, bridge circuits to the two single temperature probes concerned, and also actuate the excitation coil of the respective relay change-over switch.

This solution can. for example, be realised by means of a multiple pole-changeover switch which has a number of switching positions, corresponding to the number of readings. The change-over switch can be a rotary switch which is driven by a motor or it can be realised by a number of dry reed relays which are each provided with a corresponding number of changeover contacts and are connected to the outputs of a shift register, through which a single pulse passes, which when it reaches the register end is returned to the register beginning. In this case and in using the aforemcntioned rotary switch the changc-over switches are to be constructed as bistable relays.

The invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a schema of a heating system according to the invention: Figure 2 is a flow diagram of the regulator of the system in Figure l: Figure 3 is a switching and wiring diagram ol the regulator of Figure 2: Figures 4 and 5 each show diagrammatic ally a means for actuating the relay changeover of Figure 3, and Figures 6 and 7 show diagrammatically a third arrangement for actuating changc-over switches of Figure 3.

Referring now to Figures 1 and 2, the heating system has a closed water circulating network 10 which is filled with water to which anti-freezing means have been added.

Connected in the network 1() as in a parallel relationship to one another are a solar collector 11, comprising a multiplicity of individual elements, an air heat exchanger 12 with a fan 13, two heat exchangers 14 and 15 of a heat accummulator 16, the evaporator 17 and the condenser 18 of a heat pump 19, a heat exchanger 2() in a mains water storage tank 21, a by-pass 22 and radiators 23 for room heating. The coolant circulation of the heat pump 19 passes between the consdensor 18 and the evaporator 17 by way of an expansion valve 25 and between the evaporator 17 and the condensor 18 by way of the compressor 26 of the heat pump. The heat transfer unit 31 of a gas-fired additional heating unit 32 is connected in a forward flow line 30, of the heating network 10, between the connections of the condenser 18 and the heat exchanger 20 in the water storage tank 21. In the lower return flow line 34 of the heating network 10, 3directional valves 35 to 41 are provided at the connection points of the individual units and, dependent on an adjustment command signal of a regulator, connect to each other the two of the lines which come together at each line connection point. The valve 41 can also assume an intermediate position which is also described in more detail hereinbelow.

Moreover pumps 44 to 47 are provided at different points in the heating network and circulate the water clockwise in each circuit concerned.

The system has a regulator 50 for the forward flow water temperature whose actual value THV is obtained by a sensor 89 between the by-pass 22 and the radiators 23.

The desired value of this temperature is made dependent on meteorological conditions. For this purpose, the regulator is provided with an external detector 52.

Temperature probes 54, 55 and 56 are also provided and transmit to the regulator respectively the collector outflow temperature TKA, the ambient temperature TAI of the air heat exchanger 12 and the temperature T51 of the heat accumulator 16. In addition thereto, a temperature probe 51 is used to sense the heating water return flow temperature. and a temperature probe 57 is disposed in the air heat exchanger 12, a temperature probe 58 in the vicinity of the air heat exchanger 12 also to measure temperature TA1 and a temperature probe 59 for the temperature Taw in the water storage tank 21. The temperature probes 57 and 58 are part of a defrost thermostat 60, which when the air heat exchanger 12 ices over. introduces a defrost procedure as a priority.The temperature probe 59 belongs to a thermostat 61 which during heat consumption introduces a heating of the water storage tank 21 with a greater priority than the room heating but however with a lesser priority than the defrosting of the air heat exchanger 12.

In addition to the collector 11, a further individual collector element 62 is provided which is not connected to the water circulating network 10. The element 62 is provided with a temperature probe 63 which detects the so-called collector no load operation temperature TKL and feeds it to the regulator, TKL being a measure of the intensity of the solar radiation incident on collector 11.

The regulator 50 controls the energy sources and the other units of the heating unit in the manner of a 3-stage heating unit regulator. For this purpose, the regulator 50 has a comparator 65 which establishes the deviation of the return flow water temperature from a desired value and forms signals for low. medium and high heat consumption as well as a signal for the absence of any heat consumption. These signals are fed into a calculator 66 which, under the conditions prevailing in each case, determines the most economical use of the heat sources in accordance with predetermined criteria and signals the result of this determination to an adjusting unit 67. The latter converts the signals of the calculator into adjustment commands for the individual units of the heating system.The operative connections of the adjusting unit 67 to these units are not shown in the drawing in order to avoid obscuring the drawing. The regulator may be constructed using digital techniques. In this case. the determination of each of the adjustment values. which is to be considered as the sum of all adjustment calculations, occurs intermittently by means of a pulse generator, whose pulse frequency is matched to the thermal inertia of the heating system. However, in the regulator as shown in Figure 3, relays are used in place of the pulse generator 68 and are fed from a constant voltage source.

Figure 2 shows the operation of the regulator with reference to a reading and decision flow diagram and by means of symbols Z1 to Z14 for each of the adjustment commands which are explained below: Z1: The collector 11 heats the mains water storage tank 21 directly.

Z2: The heat accumulator 16 heats the mains water storage tank 21 directly, the collector 11 heats up, itself, in no-load operation.

Z3: The heat pump 19 heats the mains water storage tank 21, the heat accumulator 16 supplies the heat pump 19, and the collector heats up the heat accumulator 16.

Z4: The heat pump 19 heats the water storage tank 21, the heat accumulator 16 supplies the heat pump, the collector 11 heats up, itself, in no-load operation.

Z5: The heat pump 19 heats the water storage tank 21, the air heat exchanger 12 supplies the heat pump 19, the collector 11 heats up, itself, in no-load operation.

Z6: The collector 11 heats the room radiators 23 directly.

Z7: The heat accumulator 16 heats the room radiators 23 directly, the collector 11 heats up, itself, in no-load operation.

Z8: The heat pump 19 heats the room radiators 23, the collector 11 supplies the heat pump 19.

Z9: The heat pump 19 heats the room radiators 23, the heat accumulator 16 supplies the heat pump 19, the collector 11 heats up, itself, in no-load operation.

Z10: The heat pump 19 heats the room radiators 23, the air heat exchanger 12 supplies the heat pump 19, the collector 11 heats up, itself, in no-load operation.

Z11:The heating unit is not in operation, the collector 11 heats the heat accumulator 16.

Z12: The heating unit is not in operation, the air heat exchanger 12 heats the heat accumulator 16.

Z13: The heating unit is not in operation, the collector 11 heats up, itself, in no-load operation.

Z14: The heating unit is not in operation, the air heat exchanger 12 is defrosted.

The reading can take place periodically as a succession of individual readings in the reading and decision stations. The arrangement can, however, be also done in such a manner that the reading in all stations can take place simultaneously so that a reading flow in the sense of a predetermined succes sion of individual readings does not take place. In order to understand this more easily. however, the following will generally refer to a reading flow.

The individual reading and decision stations of the regulator are represented by boxes into which the decision criterion is written. The designations used for this purpose are summarised below: This Ambient temperature of the air heat exchanger 12.

TKA: Outflow temperature of the collector 11.

Ti: Temperature of the collector noload element 62, equivalent to the no-load operation temperature of the collector 11.

Tsp: Temperature in the heat accumulator 16.

Tnw: Temperature in the mains water storage tank 21.

THV: Forward circulating water flow temperature just prior to the room radiators 23.

THR: Circulating water return flow temperature just following the room radiators 23.

TA2: Ambient temperature of the external detector 52.

T57: Temperature in the air heat exchanger 12.

The yes-decisions of the individual stations are denoted by a plus, the no-decisions by a minus. The A- values of the individual readings depend on the layout in each case of the heating system and on further parameters which have an influence on the behaviour of the regulation.

Referring to Figure 2, each pulse reads temperature TA1 to give priority to the defrost thermostat 60 and actuates the adjustment command to defrost the air heat exchanvger 12, when the difference in temperature between TAl and T57 exceeds the preset value A 20 and the thermostat 60 temperature indicates an ice layer thickness on the evaporator which can no longer be tolerated for economical operation. When the result of the reading is negative, i.e.

when defrosting is not required, a pulse is passed on to the thermostat 61 which takes the decision whether the pulse is to be transmitted further to one of the reading stations 70 to 74, controlling the mins water heating, or to the comparator for the purposes of controlling the heating unit. In the first case, the pulse passes first to the station 70 which by way of adjustment command Z1 actuates a direct heating of the water storage tank 21 by means of the collector 11, when the collector outflow temperature TKA is greater than the temperature TBW in the water storage tank 21 by the threshold value Al. In the other case, the pulse goes on to station 71 which triggers by way of adjustment command Z2 a direct heating of the water storage tank 21 by the heat accumultor 16, when the temperature Tsp of the heat accumulator 16 lies above the temperature TBW of the water storage tank by the preset value A2. If this condition also is not fulfilled, then the following station 72 investigates whether the incoming solar radiation is sufficiently intense that the collector 11, despite the negative response to the reading in station 70, is, nevertheless, after a short period, capable of heating the mains water directly. This is considered to be possible when the collector no-load operation temperature TKL lies above the water storage tank temperature TBW by A3 = 30 K. In this case, adjustment command Z1 is again actuated. When the incoming solar radiation is insufficient the heat pump 19 is switched on by way of one of the stations 73 or 74.Station 73 actuates adjustment command Z5 when the external temperature TAl at the air heat exchanger 12 lies above the temperature Tsp of the heat accumulators 16 by at least the value A4. In this case, the heat pump is fed from the air heat exchanger 12, whilst the collector 11 heats up, itself, in no-load operation. If the temperature TAI does not, however, reach the pr4eviously described value, adjustment command Z3 or Z4 is actuated in station 74, dependent in each case on whether the collector outflow temperature TKA lies above the temperature Tsp of the heat accumulator 16 by a definite value A4 or not. In both cases the heat pump 19 is fed from the heat accumulator 16, whereby in Z3 the collector 11 charges the heat accumulator 16 and Z4 the collector in no-load operation heats up, itself.

The adjusting unit 67 maintains the adjustment command actuated in each case until the next reading pulse of the pulse generator by way of a store which is not shown in the drawing. The pulse intervals can be timed dependent on the thermal inertia of the system and may be of up to two minutes and longer. If in a following pulse the heat consumption in the water storage tank 21 is satisfied, the thermostat 61 directs the reading pulse over into the part of the regulator which triggers the adjustment commands for the room heating. There the pulse first arrives in the comparator 65, which dependent on desired value deviation of the forward flow temperature THV controls the heating output in three stages. The comparator 65 is, for this purpose, provided with three reading and decision stations 75, 76 and 77. The station 75 determines whether the desired value deviation ATHV exceeds a first threshold value A 6 and whether, as a result, at least a low heat consumption (Heating stage 1) or any heat consumption at all, is present.

Station 76 decides whether the desired value deviation ATHV exceeds a second threshold value A7 and whether as a result, a medium heat consumption (heating stage 2) or only a low heat consumption, is present. The station 77 takes the decision, with reference to a third threshold value A8, whether a higher (Heating stage 3) or only a medium heat consumption is present.

In the absence of any heating consumption, the reading pulse goes to the station 78 which decides whether the collector 11 is able to charge the heat accumulator 16, adjustment command Zll, or whether the collector 11 is operated for the purposes of self-charging in no-load operation, adjustment commands Z12 and Z13. When the external temperature is sufficiently high, adjustment command Z12, the heat accumulator is, moreover, charged by way of the air heat exchanger 12. In all these three operating states the valve 41 short-circuits the radiators 23 by way of the by-pass line so that no heat supply to the radiators 23 takes place.

In the case of low heat consumption (Heating stage 1) the pulse goes to station 80 which triggers by way of adjustment command Z6 a direct heating of the radiator circulating water by the collector 11, when the collector outflow temperature TKA exceeds the heating unit return flow temperature THR by the value All, e.g. by 2K. If this is not the case, station 81 decides whether the heat accumulator 16 is ready to head the radiator circulating water directly or not. In the event that it is ready, the heat exchanger 15 in the heat accumulator 16 is connected to the heating network by way of adjustment command Z7 and the collector 11 is switched to no-load operation for the purpose of self-charging.If the heat accumulator 16 is also not ready to heat directly, any heating of the circulating water at all is abandoned until the desired value deviation rises so far that a subsequent reading pulse signals medium heat consumption. Firstly, however. station 82 is actuated and reads the intensity of the incoming solar radiation with reference to a comparison of the collector no-load operation temperature TKL in the collector element 62 with the heating unit return flow temperature THR.

If the former temperature lies above the other by more than A 13 = 10K, the collector 11 is switched by way of adjustment command Z12 or Z13 to no-load operation for the purposes of charging, whereby station 79 also decides that the air heat exchanger 12 charges the heat accumulator 16, when the external temperature TAl lies above the accumulator temperature, Tsp by the predetermined value A 10. When the incoming solar radiation is insufficient, station 78 decides whether the collector 11 is in the position of charging the heat accumulator, 16 or not. When there is a positive response, the pump 44 is switched on by way of adjustment command Z I and the valves 35 and 36 adjusted so that the collector 11 is connected to the heat exchanger 14 in the heat accumulator 16.In the other case the pulse passes on to station 79 which switches the collector 11 to no-load operation by way of adjustment command Zl2 or Z13 and where necessary, places the air heat exchanger 12 in series with the heat exchanger 14 in the accumulator 16.

The co-operation of the stations 78, 79 and 82 in the first heating stage Icads as a result to the fact that when the collector 11 and the heat accumulator 16 are not ready to heat the radiator circulating water directly, the collector 11 is operated for the purpose of self-charging in no-load operation, when sufficiently intense incoming solar radiation is present. Thereby any heating of the heat accumulator by the collector is deliberately avoided. Extensive tests have shown that it is more economical to place the collector 11 again, as quickly as possible, in the position where it can heat the circulating water directly, than to let the collector work on the heat accumulator, whereby in addition to the circulating pumps, the drive unit of the heat pump also consumes energy.

When the collector 11 and the heat accumulator 16 are not ready to heat the circulating water directly, substantially the same program to charge the heat accumulator and the collector is carried out in heating stage 1 as in the absence of heat consumption, i.e. with a negative signal in station 75.

The sole difference consists in the fact that when there is strong incoming sunlight, the collector 11 is not used to charge the heat accumulator, although with regard to the temperature relationships in the collector and the heat accumulator, it would be in the position so to do. The adjustment commands Z6 and Z7 switch the valve 41 into a mid-position in which only a part of the total circulating water flows through the collector 11 of the heat accumulator 16, whilst the other part pass by way of the by-pass line 22 direct to the forward flow line 30.

When at least a medium heat consumption is detected in station 76, the reading pulse passes to station 77 in which the medium heat consumption is confirmed or an even higher heat consumption established. In the case of medium heat consumption, heating stage 2, priority is first accorded in station 83 to the collector 11 for the purpose of direct heating, when the collector outflow temperature TKA lies above the heating unit return flow temperature THR by at least 4K. In this case the adjustment command Z6 results. This case occurs, for example, when the collector 11 is switched during a preceding reading pulse by way of station 82 or 84 to no-load operation and was heated up to a sufficiently great extent by incoming solar radiation.

When the collector 11 does not fulfill the condition of the reading in station 83, the pulse passes by way of the station 84 and 85 on to one of the stations 86, 87 or 88, which switches on the heat pump 19 by way of one of the adjustment commands Z8 to Z10.

First, the question as to the incoming solar radiation is again put in station 84. When the collector no-load operation temperature TK6 lies above the heating unit return flow temperature THR by more than 40 K, a feeding of the heat pump by means of the collector 11 is disregarded, and the latter is switched to no-load operation for the purposes of self-charging. Station 88 then decides only whether the heat accumulator 16 or the air heat exchanger 12 is called upon to feed the heat pump, according to the adjustment commands Z9 or ZlO.

When the incoming solar radiation is less intense it is not possible to count on the collector 11 charging quickly and soon being ready for direct heating, so that the collector is included in the reading as a head source for the feeding of the heat pump 19. The reading pulse passes first to station 85 which determines whether the external temperature TAl lies above the temperature of the heat accumulator Tsp by a definite threshold value Awl6. If this is not the case station 86 determines whether the collector outflow temperature TKA lies above the temperature of the heat accumulator by a minimum value A 17, e.g. by 5K. When this is so the collector 11 is called upon to feed the heat pump.If TKA lies below this value, the heat exchanger 15 of the heat accumulator 16 is connected in series to the evaporator 17 of the heat pump. When station 85 detects that Taxi lies above Tsp the air heat exchanger 12 is selected as a heat source for the heat pump by way of adjustment command Z10.

An exception to this is made only if TKA lies above TAI by more than A 18 e.g. 15K. In this case the collector 11 again comes into play as a heat source for the heat pump 19 by way of adjustment command Z8. In each case in heating stage 2, the valve 41 is switched so that no circulating water can flow through the by-pass line 22.

When station 77 of the comparator 64 signals a high heat consumption or heating stage 3. the additional heating unit 32 is switched on and triggers station 85 directly, by-passing the stations 83 and 84, by way of which station 85 an operation using the heat pump 19 is selected in the manner described above. Here a reading as to the readiness of the collector for direct heating is abandoned as the collector, even when fully warmed up. cannot cover the high heat consumption in heating stage 3. In heating stage 3 as well, the valve 41 shuts off the by-pass line 22 so that the entire circulating water flows through the condensor 18 of the heat pump 19.

To realise in the embodiments of Figures 3 to 7, the programme described, relay change-over switches S1 to S16 are associated with the individual reading stations of the regulator 50; and their change-over contacts as shown in Figure 3, are connected on the input side to a constant voltage source 100. For the sake of simplicity the excitation coils of the relay change-over switches S1 to S16 are not shown in Figure 3. The defrost sensor 60, the mains water thermostat 61 and the three-stage heating thermostat 65 are all constructed so that their output signal is constituted by a particular switching state of their changeoverswitches.These and the change-over switches -S1 to S16 control a number of output lines 101 to 114, corresponding to the number of adjustment commands Z1 to Z14, which are connected by way of a crossbar distributor 115 to the respective excitation coils 116 to 127 of the units controlling the heating system, or to the contactors, controlling these units. These excitation coils are associated individually with the following units.

Excitation coil 116: Pump 44 Excitation coil 177: Pump 45 Excitation coil 118: Pump 46 Excitation coil 119: Pump 47 Excitation coil 120: Valve 35 Excitation coil 121: Valve 36 Excitation coil 122: Valve 37 Excitation coil 123: Valve 38 Excitation coil 124: Valve 39 Excitation coil 125: Ventilator 13 Excitation coil 126: Compressor 26 of the heat pump 19 Excitation coil 127: Additional heating unit 32.

The excitation coil 128 is the coil of a relay and is connected to the one output of the third stage of the heating thermostat or of the comparator 65 and its switching contact 129 monitors the circuit of the excitation coil 127 for the relay controlling the additional heating unit 32.

It can be seen from Figure 3 that in each case only one of the lines 101 to 114 can carry current to actuate a respective adjustment command. The electrical connections in the crossbar distributor 115 are so provided that by way of each of the lines 101 to 114 that switching state is actuated which corresponds to the adjustment command located at the like point in the flow diagram in Figure 2. In order to indicate in each case the prevailing operating state a number of control lights 130 are provided corresponding to the number of the adjustment com mands.

As is demanded in Figure 2 the position of the relay change-over switches S1 to S16 is to be depenxdent on a difference in temperature A between each two of the six temperatures TKA, TKL, TSP, TAi, Tnw, and THR.

In the first embodiment in Figure 4 each change-over switch S1 to S16 is operated by a corresponding pair of temperature probes in a bridge circuit by way of switching amplifier V. For the sake of simplicity only the bridge circuits for the change-over switches S1 S2 and S16, associated with the reading switches 70, 71 and 88, are shown.

The reading station 70 determines whether the collector outflow temperature TKA iS greater than the temperature Tnw in the mains water storage tank 21 by more than A 1. The bridge circuit for the corresponding change-over switch S1 thus contains a temperature-dependent resistor RKA which detects the collector outflow temperature TKA and a temperature-dependent resistor Rnw which detects the temperature TBW of the water storage tank. A potentiometer Rsl is provided to adjust the switching threshold A 1 and its movable tap with the bridge voltage source Uf, is located in the diagonal arm of the bridge.Two variable resistors Ry1 are connected to the input of the amplifier V, by means of which resistors the amplification and thus the switching hystereses can be adjusted or varied within certain limits. When the collector outflow temperature TKA exceeds the water storage tank temperature TBW by the required switching threshold A 1, the amplifier is switched and the relay change-over switch operates, by which means the desired switching procedure is actuated.

The change-over switch S2 is triggered according to the reading station 71 by a bridge circuit in which a temperaturedependent resistor Rsp, detecting the temperature Tsp in the heat accumulator 12, a temperature-dependent resistor RBW, detecting the temperature TBW in the water storage tank 21 and a potentiometer R52 are connected. The latter can be of the same design as the potentiometer R51 and differs from it only by a different adjustment of its movable tap. Two resistors Rv2 are connected to the input of the amplifier V and may have the same values as resistors Ry1, or they could have resistance values differing therefrom according to operational requirements.The bridge circuits for all the remaining reading stations which are represented as shown by the station 16, are constructed in a similar manner. Temperature sensors are formed in this way for the temperatures to be measured; the sensors being represented symbolically in Figure 4 by areas of vertical strips.

In order to reduce the number of temperature probes, only a single temperature probe need be used at each place where a temperature is to be measured and its ouftput signal fed in by suitable means, to each of the bridge circuits concerned.

Such an arrangement is shown diagrammatically in Figure 5. The measuring probe for a location at which temperature is to be measured is indicated by the designation RT and is constituted by a temperaturedependent resistor. The probe is connected in series with a fixed resistor RA in the one bridge arm of a bridge circuit and a fixed resistor Rn is connected in its other bridge arm in series with a comparison resistor Re in the form of a potentiometer. An amplifier V is connected to the bridge circuit by way of two resistors RV and controls a direct current motor 140 which moves a toothed rack 142 by way of a toothed pinion 141.

The one end of the movable tap 144 of the comparison resistor RG; which tap is constructed as a two-armed lever, is articulated at this rack. Variable resistor R1 to R16 are associated with the bridge circuits for the individual relay change-over switches S1 to S16, of which resistors only R1 and R2 are shown in the drawing. The taps 146 of the variable resistors R, to R,6, which taps are likewise constructed as two-armed levers, are articulated, like the tap 144 of the comparison resistor R(;, at the toothed rack 142, so that any displacement of the toothed rack 142 adjusts the taps of the resistors RG and R1 to Rld26 in the same direction.The resistors R1 and R16 respectively replace the temperature-dependent resistor of Figure 4 serving to measure the same temperature in the individual bridge circuits as the single probe RT measures. The motor 140 displaces, when the temperature of the measuring point concerned alters, the toothed rack 142 so far until the comparsison resistor RG and the variable resistors R1 to R16 have the same resistance value as the temperature probe RT. In this manner, the variable resistors Rl R16 perform the same function as the given temperature- dependent resistors Rsp, RBW, etc. in the circuit in Figure 4.

The third embodiment in Figures 6 and 7 shows a simpler arrangement having a reduced number of temperature probes, that is one for each location at which a temperature is to be sensed. In this arrangement, a drum controller 150 (Figure 7) is provided which has sixteen switching contacts a to al6 to el to el6, in each of five switch wafers A to E. The drum controller is driven rotatably by a direct current motor, whereby, corresponding to the number of reading stations, it passes through sixteen switching position in which, in each case, it pauses for a few seconds. Figure 7 shows only the switching contacts of the three switching positions, 1, 2 and 16, which correspond to the reading stations 70, 71 and 88.In each switching position the drum controller produces a bridge circuit by way of which the corresponding relay change-over switches Sl to S16 are triggered. The arrangement of the switching contacts a to e in the bridge circuits can be seen in principal in Figure 6 in which the bridge circuit for the first switching position corresponding to the reading station 70 is shown as being representative of the other positions. The same reference numerals are thereby chosen for the individual circuit elements as in Figure 4.

The function of the drum controller 150 can also be realised by means of a corresponding number of dry reed relays having each five pairs of contacts, which are connected to the outputs of a shift register through which a single pulse passes which, when it reaches the end of the register, is returned to the beginning of the register.

WHAT WE CLAIM IS: l. A circulating water heating system, having a circulating water network and comprising a heat consuming device, two energy sources, a heat accumulator which can be charged by the two energy sources, a heat pump, the system providing means to connect at least one of the energy sources and/or the heat accumulator directly to said network, and to connect the heat pump to pump heat from the two energy sources and/or the heat accumulator into the circulating water network, and a regulator for regulating the circulating water temperature, wherein the regulator comprises a calculator which compares signals indicative of the temperatures of the heat sources and the heat accumulator in accordance with a predetermined reading schema both with one another as well as with a signal indicative of the circulating water temperature of the consuming device, and determines therefrom the mode of operation of the components of the system to provide the most favourable mode in any given circumstances with regard to economy of operation and to actuate said means accordingly.

2. A system according to claim 1, wherein one of the energy sources is a solar collector, and the other of the energy sources is an environmental heat exchanger, of which energy sources the collector is the one which as least can be connected by said means directly to said network.

3. A system according to claim 2, wherein the regulator controls the supply of heat to the circulating water network in at least two stages by determination of the deviation, if any, of the required temperature of the circulating water from the actual temperature thereof.

4. A system in accordance with claim 3, wherein in the first heating stage the regulator reads with greater priority the readiness of the collector for direct heating of the circulating water and with lower priority that of the heating accumulator, and when the collector or the heating accumulator is of a sufficiently high temperature causes a direct transfer of the heat, produced in the collector of stored in the heat accumulator, as the case may be to the heat consuming device, and, when the collector and the heat accumulator are not thus ready to heat directly, effects, whilst preventing a heat transfer to the heat consuming device, a heating up of the heat acumulator by means of the collector or, with lower priority, by means of the environmental heat exchanger, and/or permits a heating up of the collector by means of switching it to no-load operation.

5. A system in accordance with claim 3 or 4, wherein the heat requirement of the circulating water for any given temperature of heating it is to provide is determined by the regulator in dependence on meteorlogical conditions and/or ambient temperature.

6. A system in accordance with any of claims 3, 4 and 5, wherein, in the second heating stage the regulator reads with grea ter priority the readiness of the collector to directly heat the heat consuming device and, when the collector is so ready connects the heating network directly to the collector, or when, on the contrary, the collector is not so ready, connects the collector to the evaporator of the heat pump and causes the heat pump to operate.

7. A system in accordance with claim 6, wherein the regulator requires a higher temperature of the collector for direct heating of the heat consuming device in the second heating stage than it does in the first heating stage.

8. A system in accordance with claim 6 or 7, wherein in the second heating stage the collector is connected to the evaporator of the heat pump, when the collector outflow temperature (TKA) is not sufficient to heat the circulating water directly, but lies by a preset value above the temperature (top) of the heat accumulator and by a preset value above the ambient temperature (TAI) at the environmental heat exchanger.

9. A system in accordance with claim 8, wherein, in the second heating stage the heat accumulator is connected to the evaporator of the heat pump, when the ambient temperature (TA1) and the collector outflow temperature (TKA) do not exceed the accumulator temperature (asp) by preset values.

10. A system in accordance with claim 9, wherein in the second heating stage the environmental heat exchanger is connected to the evaporator of the heat pump. when

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

contacts of the three switching positions, 1, 2 and 16, which correspond to the reading stations 70, 71 and 88. In each switching position the drum controller produces a bridge circuit by way of which the corresponding relay change-over switches Sl to S16 are triggered. The arrangement of the switching contacts a to e in the bridge circuits can be seen in principal in Figure 6 in which the bridge circuit for the first switching position corresponding to the reading station 70 is shown as being representative of the other positions. The same reference numerals are thereby chosen for the individual circuit elements as in Figure 4.

The function of the drum controller 150 can also be realised by means of a corresponding number of dry reed relays having each five pairs of contacts, which are connected to the outputs of a shift register through which a single pulse passes which, when it reaches the end of the register, is returned to the beginning of the register.

WHAT WE CLAIM IS: l. A circulating water heating system, having a circulating water network and comprising a heat consuming device, two energy sources, a heat accumulator which can be charged by the two energy sources, a heat pump, the system providing means to connect at least one of the energy sources and/or the heat accumulator directly to said network, and to connect the heat pump to pump heat from the two energy sources and/or the heat accumulator into the circulating water network, and a regulator for regulating the circulating water temperature, wherein the regulator comprises a calculator which compares signals indicative of the temperatures of the heat sources and the heat accumulator in accordance with a predetermined reading schema both with one another as well as with a signal indicative of the circulating water temperature of the consuming device, and determines therefrom the mode of operation of the components of the system to provide the most favourable mode in any given circumstances with regard to economy of operation and to actuate said means accordingly.
2. A system according to claim 1, wherein one of the energy sources is a solar collector, and the other of the energy sources is an environmental heat exchanger, of which energy sources the collector is the one which as least can be connected by said means directly to said network.
3. A system according to claim 2, wherein the regulator controls the supply of heat to the circulating water network in at least two stages by determination of the deviation, if any, of the required temperature of the circulating water from the actual temperature thereof.
4. A system in accordance with claim 3, wherein in the first heating stage the regulator reads with greater priority the readiness of the collector for direct heating of the circulating water and with lower priority that of the heating accumulator, and when the collector or the heating accumulator is of a sufficiently high temperature causes a direct transfer of the heat, produced in the collector of stored in the heat accumulator, as the case may be to the heat consuming device, and, when the collector and the heat accumulator are not thus ready to heat directly, effects, whilst preventing a heat transfer to the heat consuming device, a heating up of the heat acumulator by means of the collector or, with lower priority, by means of the environmental heat exchanger, and/or permits a heating up of the collector by means of switching it to no-load operation.
5. A system in accordance with claim 3 or 4, wherein the heat requirement of the circulating water for any given temperature of heating it is to provide is determined by the regulator in dependence on meteorlogical conditions and/or ambient temperature.
6. A system in accordance with any of claims 3, 4 and 5, wherein, in the second heating stage the regulator reads with grea ter priority the readiness of the collector to directly heat the heat consuming device and, when the collector is so ready connects the heating network directly to the collector, or when, on the contrary, the collector is not so ready, connects the collector to the evaporator of the heat pump and causes the heat pump to operate.
7. A system in accordance with claim 6, wherein the regulator requires a higher temperature of the collector for direct heating of the heat consuming device in the second heating stage than it does in the first heating stage.
8. A system in accordance with claim 6 or 7, wherein in the second heating stage the collector is connected to the evaporator of the heat pump, when the collector outflow temperature (TKA) is not sufficient to heat the circulating water directly, but lies by a preset value above the temperature (top) of the heat accumulator and by a preset value above the ambient temperature (TAI) at the environmental heat exchanger.
9. A system in accordance with claim 8, wherein, in the second heating stage the heat accumulator is connected to the evaporator of the heat pump, when the ambient temperature (TA1) and the collector outflow temperature (TKA) do not exceed the accumulator temperature (asp) by preset values.
10. A system in accordance with claim 9, wherein in the second heating stage the environmental heat exchanger is connected to the evaporator of the heat pump. when

the ambient temperature (TAl) exceeds the accumulator temperature (asp) by a preset value and the collector outflow temperature (TKA) does not lie above the ambient temperature (TAI) by a preset value.
11. A system in accordance with claims 9 and 10, wherein the regulator stops the heat carrier throughflow through the collecfor. when the evaporator of the heat pump, in operation, is connected to the heat accumulator or to the environmental heat exchanger.
12. A system in accordance with any of preceding claims 3 to 11, having an additional heating unit as a third heat source, wherein the regulator controls the heating output in three stages, whereby in the third stage. corresponding to the greatest heat consumption, the priority reading of the readiness of the collector for direct heating of the circulating water is omitted and the additional heating unit as well as the heat pump are switched on at once, and the heat source for the pump being the one of the collector, heat accumulator and the environmental heat exchanger, is determined by the regulator in accordance with the same reading schema as in the second heating stage;
13.A system in accordance with any of the preceding claims 3 to 11. wherein the regulator influences a valve device in a by-pass line of the heat consuming device in such a manner that in the first heating stage a part of the return flow water from that device flows by way of the by-pass line directly to the forward flow line to the device: the by-pass line being closed otherwise.
14. A system in accordance with any of the preceding claims 3 to 11, wherein the regulator in the absence of heat consumption connects the collector with the greater priority. and the environmental heat exchanger with a lesser priority, to the heat accumulator to heat up the latter or switches the collector to no-load operation.
15. A system in accordance with any of the preceding claims, for heating rooms and heating water, having a heat exchanger which is connected in parallel with the heat consuming device, being set of radiators, and is disposed within a storage tank for the water, and comprising a regulator to control heating of the water tank heat exchanger, and means for serving, with priority, the heat exchanger of the water tank when the regulator indicates heating of the water is needed, wherein the regulator for the water tank determines in any given circumstances the most advantageous one of the heating source by means of temperature comparison therebetween.
16. A system in accordance with claim 15, wherein the regulator for the water tank determines. with greater priority, the readiness of the collector for the direct heating of the water storage tank and with lower priority that of the heat accumulator, and connects the heat exchange unit in the water storage tank, according to the priority, directly to the collector or to the heat accumulator, if these have a sufficiently high temperature, or if not, to the condenser of the heat pump and, in the latter case, causes the heat pump to operate.
17. A system in accordance with any of the preceding claims, wherein the regulator for the water tank is operated by a pulse generator, and the reading as to the heat source which in each case is most advantageous takes place in time intervals dependent on the thermal inertia of the heating unit.
18. A system in accordance with any of claims 15 to 17, wherein the regulator for the room heating and the regulator for the water storage tank have said calculator in common and the calculator is such that its programme can be adjusted by said means for serving, with priority, the water storage tank.
19. A system in accordance with any of the preceding claims, wherein there are provided a collector no-load operation element, not connected to receive circulating water, and a temperature sensor detecting the temperature of this no-load element to provide an indication to the regulator of the intensity of the incoming solar radiation, and wherein the regulator acts to stop the through flow of the heat transfer medium through the collector, when the intensity of the incoming solar radiation as measured by the no-load element is such as to be able to heat the collector to the condition in which it may be used directly to heat the heat consuming device.
20. A system in accordance with claim 19, wherein the decision criterion of the reading as to the intensity of the incoming solar radiation rests on the fact of whether the collector no-load operation temperature (TKL) lies above the temperature of the heat-transfer medium by a definite threshold difference.
21. A system acording to claim 20, wherein said threshold difference is 20"K.
22. A device in accordance with claim 20 or 21, wherein the regulator of the circulating water network in the first heating stage undertakes the reading as to the intensity of the incoming solar radiation in accordance with a decision of the nonreadiness of the collector and the heat accumulator directly to heat the heat consuming device.
23. A device in accordance with claims 20, 21 or 22, wherein the regulator in the second heating stage undertakes the reading as to the intensity of the incoming solar radiation in accordance with the decision on the non-readiness of the collector directly to heat the heat consuming device.
24. A device in accordance with claims 15 and 19, wherein the regulator undertakes the reading as to the intensity of the incoming solar radiation in accordance with a decision as to the non-readiness of the collector and the heat accumulator directly to heat the water storage tank.
25. A device in accordance with any of the preceding claims 3 to 24, wherein the regulator reads, with greater priority, the iced-over condition of the environmental heat exchanger which is constructed as an air heat exchanger and introduces a defrost procedure when the difference in temperature between the temperature probes in the air heat exchanger and in its environment exceeds a preset value.
26. A system according to any of the preceding claims, wherein the calculator comprises outputs for respective operating modes of the system, and decision stations by which an operating signal is routed to a respective output according to the temperature indications provided by the input signals to the regulator and wherein relay change-over switches are associated with the decision stations of the regulator, and the switching contacts of the relay change-over switches are supplied by a constant voltage source, and the excitation coils of the relay change-over switches are each actuated by means of a bridge circuit comprising a temperature probe pair, of a respective decision station.
27. A system in accordance with claim 26, wherein the excitation coils of the relay change-over switches are connected with an operational amplifier and with potentiometers for the purposes of adjusting the switching hystereses of the change-over switches in the diagonal arm of the bridge circuit.
28. A system in accordance with claim 26 or 27. wherein the excitation coils are connected in series with said amplifiers and potentiometers.
29. A system in accordance with claims 26, 27 or 28, wherein a single temperature probe, being a temperature-dependent resistor, is used for each place at which a temperature is to be measured. and its signal is used to adjust respective variable resistors of the individual decision stations, whereby the variable resistors act as temperature probes.
30. A system in accordance with claim 29, wherein the signal of the single temperature probe is used to operate a direct current motor in the diagonal arm of a bridge circuit and the motor is used to operate said variable resistors in response to said signal, and also a variable comparison resistor of the bridge circuit so as again to balance the bridge.
31. A system in accordance with claim 26,27 or 28, wherein a single temperature probe is used for each place at which temperature is to be measured, and a switching device, which operates automatically, is provided which forms, according to the reading sequence of the regulator, in running sequence, bridge circuits to the two single temperature probes concerned, and also actuates the excitation coil of the respective relay change-over switch.
32. A system in accordance with claim 31, wherein the switching device is a multiple pole change-over switch which has a number of switching positions, corresponding to the number of decision stations.
33. A system in accordance with claim 32, wherein the multiple-pole switch is a rotary switch driven by a motor successively through its switching positions.
34. A system in accordance with claim 32, wherein the switching device comprises a plurality of dry reed relays, one for each decision station, each provided with a respective number of change-over contacts, a shift register providing a signal output for each relay, the relays being connected to the respective outputs of the register, and the last stage of the register being connected to the first stage thereof.
35. A circulating water heating system substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.
36. A circulating water heating system substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.
37. A circulating water heating system substantially as hereinbefore described with reference to Figures 1 to 3 and Figure 4 or Figure 5 or Figures 6 and 7 of the accompanying drawings.