IE20170068A1 - A method and a system and apparatus for coupling an open heating circuit to a closed heating circuit - Google Patents

Abstract

A heating system (1) comprises an open heating circuit (3) comprising a solid fuel stove (10) and a closed heating circuit (5) comprising a burner boiler unit (32) connected together by a heat exchanger (70) in which a first heat transfer fluid of the open heating circuit (3) is separated from a second heat transfer fluid of the closed heating circuit (5), and by a domestic hot water buffer tank (18). The buffer tank (18) comprises a primer coil (16) through which heat is leaked from the open heating circuit (3) into domestic water in the buffer tank (18) and a secondary heating coil (20) for heating the domestic water in the buffer tank (18) from the closed heating circuit (5). First and second pumps (73, 90) which control the flow of the first and second heat transfer fluids, respectively, through the heat exchanger (70) are operated in response to the temperature of the first heat transfer fluid in the open heating circuit (3) monitored by the thermostat (72) exceeding 65°C for transferring heat from the first heat transfer fluid to the second heat transfer fluid, and to draw the first heat transfer fluid through the primary coil (16) via a venture injector Tee connector (80) in the first closed heating circuit to sink heat from the first heat transfer fluid to the domestic water in the buffer tank (18). <Figure 1>

Description

LODGED "A method and a system and apparatus for coupling an open heating circuit to a closed heating circuit The present invention relates to a method, a connecting system and apparatus for coupling an open heating circuit to a closed heating circuit, and the invention also relates to a heating system comprising an open heating circuit coupled to a closed heating circuit.

Open heating circuits of the type comprising a heat source and domestic hot water tank are well known. Such open heating circuits may also comprise a number of space heating radiators through which water heated by the heat source is circulated for space heating. The domestic hot water tank of such an open heating circuit, in general, comprises an indirect tank whereby the heated water from the heat source is passed through a heating coil located in the indirect tank for heating domestic water therein. The heat source of such open heating circuits may be a back boiler, an oil or gas fired boiler, a condensing boiler or the like. Indeed, it is not unusual for open heating circuits to comprise more than one heat source, such as a back boiler and an oil or a gas fired boiler. However, in all such open heating circuits the water in the open heating circuit is pressurised by water in a header tank which is connected into the open heating circuit at a convenient location by a feeder pipe. An expansion pipe is also provided from the open heating circuit for accommodating expansion of the water in the open heating circuit. The expansion pipe, in general, is positioned with the outlet of the expansion pipe located above the header tank to deliver water resulting from expansion of the water in the open heating circuit back to the header tank.

Closed heating circuits, on the other hand, in general comprise a heat source with a plurality of space heating radiators through which water heated by the heat source is circulated. Typically, an indirect tank for producing domestic hot water is also provided in the closed heating circuit, and the water from the closed heating circuit is circulated through a coil in the indirect tank for heating domestic water therein. The boiler in such closed heating circuits may be a gas fired boiler, an oil fired boiler, a condensing boiler or the like. The water in such closed heating circuits is pressurised by means of a pressure vessel, typically of the type which comprises a pair of chambers separated by a diaphragm. The water of the closed heating circuit is located in the chamber on one side of the diaphragm, while the chamber on the other side of the diaphragm is pressurised by a suitable pressurised gas, for example, air or the like. Indeed, such closed heating circuits may comprise a number of heat sources, which typically, feed to a null point manifold.

In many cases it would be desirable to couple an open heating circuit with a closed heating circuit. However, because an open heating circuit is pressurised by a header tank, which is open to atmosphere, and a closed heating circuit is sealed and pressurised by a pressurising vessel, there is no suitable method of coupling an open heating circuit into a closed heating circuit whereby safety is not compromised.

There is therefore a need for a method for coupling an open heating circuit to a closed heating circuit which allows both circuits to be coupled with safety. There is also a need for a connecting system and apparatus for coupling an open heating circuit to a closed heating circuit, and there is also a need for a heating system which comprises an open heating circuit and a closed heating circuit coupled together.

The present invention is directed towards providing such a method, a connecting system and apparatus, and the invention is also directed towards providing a heating system which comprises an open heating circuit coupled to a closed heating circuit.

According to the invention there is provided a method for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid in the open heating circuit, to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid in the closed heating circuit, the method comprising connecting the open heating circuit into a heat leaking means, connecting the open heating circuit to a heat exchanger and connecting the closed heating circuit to the heat exchanger with the first and second heat transfer fluids separated from each other for transferring heat from the first heat transfer fluid to the second heat transfer fluid, locating a first pumping means configured to pump the first heat transfer fluid through the heat exchanger, locating a means in the open heating circuit for drawing the first heat transfer fluid through the heat leaking means in response to the first pumping means pumping the first heat transfer fluid through the heat exchanger.

Preferably, the means for drawing the first heat transfer fluid through the heat leaking means comprises a venturi element through which the first heat transfer fluid pumped through the heat exchanger is delivered, and advantageously, the venturi element is located between the heat exchanger and the first heat source, so that the first heat transfer fluid is delivered through the venturi element after the first heat transfer fluid has passed through the heat exchanger, and preferably, the venturi element is configured for drawing the first heat transfer fluid from the heat leaking means to the first heat source.

In one aspect of the invention the first pumping means is located in series with the heat exchanger and the first heat source. Preferably, the first pumping means and the heat exchanger are located in a bypass circuit, the bypass circuit bypassing the heat leaking means.

In another aspect of the invention the first pumping means is responsive to the temperature of the first heat transfer fluid from the first heat source rising to a first predefined temperature for pumping the first heat transfer fluid through the heat exchanger. Preferably, the first predefined temperature is greater than 55°C, and advantageously, the first predefined temperature is greater than 60°C, and ideally, the first predefined temperature is approximately 65°C.

In a further aspect of the invention the first pumping means comprises a first electrically powered pump.

In another aspect of the invention a second pumping means is provided for pumping the second heat transfer fluid through the heat exchanger. Advantageously, the second pumping means is located in series with the heat exchanger.

Preferably, the second pumping means is responsive to the temperature of the first heat transfer fluid from the first heat source rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat transfer fluid to the second heat transfer fluid.

In another aspect of the invention the second pumping means comprises a second electrically powered pump.

In one aspect of the invention the heat leaking means comprises a buffer tank, and preferably, an indirect buffer tank, and advantageously, the heat leaking means comprises a primary heat exchange coil located in the buffer tank, and preferably, the open heating circuit is connected to the one of the buffer tank and the primary heat exchange coil in the indirect buffer tank so that the first heat transfer fluid is circulated from the first heat source through the one of the buffer tank and the primary heat exchange coil located in the buffer tank.

In another aspect of the invention the closed heating circuit is connected to the buffer tank with the first and second heat transfer fluids separated from each other. Preferably, the closed heating circuit is connected to a secondary heat exchange coil in the buffer tank, and advantageously, the closed heating circuit is connected to the one of the buffer tank or the secondary heat exchange coil in the buffer tank so that the second heat transfer fluid is circulated through the one of the buffer tank and the secondary heat exchange coil of the buffer tank from the closed heating circuit.

In another aspect of the invention the buffer tank comprises a buffer tank for heating a domestic hot water supply.

In another aspect of the invention the open heating circuit is connected to a header tank by a feed pipe.

In another aspect of the invention a heat lock bend is located in the feed pipe to prevent back-feed of the first heat transfer fluid from the open heating circuit to the header tank.

In another aspect of the invention an expansion pipe is connected to the open heating circuit for accommodating expansion of the first heat transfer fluid in the open heating circuit.

Advantageously, the feed pipe is coupled to the expansion pipe at a location intermediate the heat lock bend and the open heating circuit. Preferably, the feed pipe is coupled to the expansion pipe through a non-return valve, and preferably, through a spring loaded non-return valve. Advantageously, the non-return valve is configured to prevent flow of the first heat transfer fluid from the.feed pipe to the expansion pipe.

In another aspect of the invention the second heat transfer fluid in the closed heating circuit is pressurised by a pressurising element, and advantageously, the closed heating circuit is a fully sealed heating circuit.

The invention also provides a connecting system for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid, to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the connecting system comprising a means for connecting the open heating circuit to a heat leaking means, a heat exchanger for connecting the open heating circuit and the dosed heating circuit thereto with the first and second heat transfer fluids separated from each other for transferring heat from the first heat transfer fluid to the second heat transfer fluid, a first pumping means configured to pump the first heat transfer fluid through the heat exchanger, and a means for locating in the open heating circuit for drawing the first heat transfer fluid through the heat leaking means in response to the first pumping means pumping the first heat transfer fluid through the heat exchanger.

In one aspect of the invention the means for drawing the first heat transfer fluid through the heat leaking means comprises a venturi element, the venturi element being configured for locating between the heat exchanger and the first heat source for accommodating the first heat transfer fluid from the heat exchanger to the first heat source, and the venturi element having a low pressure port for connecting to a return outlet port from the heat leaking means for receiving return first heat transfer fluid from the heat leaking means for delivery to the first heat source.

Preferably, the first pumping means is located in series with the heat exchanger and the first heat source. Preferably, the first pumping means and the heat exchanger are located in a bypass circuit, and advantageously, the bypass circuit is configured to bypass the heat leaking means.

In one aspect of the invention the first pumping means is responsive to the temperature of the first heat transfer fluid rising to a first predefined temperature for circulating the first heat transfer fluid through the heat exchanger. in another aspect of the invention the first pumping means comprises a first electrically powered pump.

Preferably, a second pumping means is provided for pumping the second heat transfer fluid through the heat exchanger.

In another aspect of the invention the second pumping means is located in series with the heat exchanger.

Preferably, the second pumping means is responsive to the temperature of the first heat transfer fluid rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat transfer fluid to the second heat transfer fluid.

In one aspect of the invention the heat leaking means comprises a buffer tank, and preferably, an indirect buffer tank, and advantageously, the heat leaking means comprises a primary heat exchange coil located in the buffer tank, and preferably, the open heating circuit is connected to the one of the buffer tank and the primary heat exchange coil in the indirect buffer tank so that the first heat transfer fluid is circulated from the first heat source through the one of the buffer tank and the primary heat exchange coil located in the buffer tank.

In another aspect of the invention the closed heating circuit is connected to the buffer tank with the first and second heat transfer fluids separated from each other. Preferably, the closed heating circuit is connected to a secondary heat exchange coil in the buffer tank, and advantageously, the closed heating circuit is connected to the one of the buffer tank or the secondary heat exchange coil in the buffer tank so that the second heat transfer fluid is circulated through the one of the buffer tank and the secondary heat exchange coil of the buffer tank from the closed heating circuit.

In another aspect of the invention the buffer tank comprises a buffer tank for heating a domestic hot water supply.

The invention also provides a heating system comprising an open heating circuit comprising a first heat source for heating a first heat transfer fluid, and a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the open heating circuit being connected to the closed heating circuit by the connecting system according to the invention, with the open heating circuit being connected to a heat leaking means, and the heat exchanger being connected to the open and closed heating circuits with the first and second heat transfer fluids separated from each other therein, and the means for drawing the first heat transfer fluid from the heat leaking means being located in the open heating circuit for delivering the first heat transfer fluid from the heat exchanger to the first heat source and for drawing return first heat transfer fluid from the heat leaking means and delivering the return first heat transfer fluid to the first heat source.

Preferably, the first pumping means of the connecting system is located in series with the heat exchanger and the first heat source, and advantageously, the first pumping means and the heat exchanger are located in a bypass circuit, and the bypass circuit is located to bypass the heat leaking means.

In one aspect of the invention a first temperature monitoring means is provided for monitoring the temperature of flow heat transfer fluid from the first heat source, and preferably, the first pumping means is responsive to the temperature monitored by the first temperature monitoring means rising to the first predefined temperature for pumping the first heat transfer fluid through the heat exchanger.

Preferably, the second pumping means of the connecting system is connected in series with the heat exchanger, and ideally, the second pumping means is configured to draw return second heat transfer fluid from the closed heating circuit and to deliver the return second heat transfer fluid to the heat exchanger. Ideally, the second pumping means is configured to pump the second heat transfer fluid through the heat exchanger and to return the second heat transfer fluid from the heat exchanger to the closed heating circuit. Ideally, the second pumping means pumps the second heat transfer fluid between the heat exchanger and a null point manifold of the closed heating circuit.

Preferably, the second pumping means is responsive to the temperature monitored by the first temperature monitoring means rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat transfer fluid to the second heat transfer fluid.

Further the invention comprises apparatus for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the apparatus comprising a heat exchanger for connecting to the open heating circuit and the closed heating circuit for transferring heat from the first heat transfer fluid to the second heat transfer fluid with the first and second heat transfer fluids separated from each other, a means for connecting the open heating circuit to a heat leaking means, a first pumping means for pumping the first heat transfer fluid through the heat exchanger, a means for drawing return first heat transfer fluid from the heat leaking means for delivery to the first heat source, the means for drawing the first heat transfer fluid from the heat leaking means being connected to the heat exchanger and configured for connecting to a return inlet port of the first heat source, and a second pumping means for pumping the second heat transfer fluid through the heat exchanger for transferring heat from the first heat transfer fluid to the second heat transfer fluid, the heat exchanger, the first and second pumping means, and the means for drawing the first heat transfer fluid from the heat leaking means being provided as an integral unit, and comprising a first inlet port and a first outlet port for connecting the apparatus into the open heating circuit, a second inlet port and a second outlet port for connecting the apparatus to the closed heating circuit, and a third inlet port and a third outlet port for connecting the apparatus to the heat leaking means.

In one aspect of the invention the second pumping means and the heat exchanger are connected in series between the second inlet port and the second outlet port, and preferably, the second pumping means is connected to the second inlet port and the heat exchanger is connected to the second outlet port. Advantageously, the second inlet port is configured for connecting to a return supply of the second heat transfer fluid of the closed heating circuit, and the second outlet port is configured for connecting to a flow supply of the second heat transfer fluid of the closed heating circuit.

In another aspect of the invention the first inlet port and the third outlet port are interconnected, and preferably, the first inlet port and the third outlet port are connected to the heat exchanger through a Teed connection between the first inlet port and the third outlet port.

Preferably, the means for drawing return first heat transfer fluid from the heat leaking means comprises an injector Tee connector, the low pressure connection of the injector Tee connector being connected to the third inlet port, and advantageously, the third inlet port is connected to the first outlet port through the injector Tee connector.

Preferably, the heat exchanger, the first pumping means and the injector Tee connector are connected in series between the first inlet port and the first outlet port, and advantageously, the third inlet port is connected to the first outlet port through the injector Tee connector, so that when the first pumping means is operational, return first heat transfer fluid is drawn in through the third inlet port through the injector T ee connector.

Preferably, the first and second pumping means, the heat exchanger and the means for drawing the first heat transfer fluid from the heat leaking means are located in a housing, with the first, second and third iniet and outlet ports located exteriorly of the housing.

The invention will be more clearly understood from the following description of some preferred embodiments thereof, which are given by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a circuit diagram of a heating system according to the invention, Fig. 2 is a circuit diagram of apparatus also according to the invention for use in the heating system of Fig. 1, Fig. 3 is a circuit diagram of apparatus according to another embodiment of the invention for use in the heating system of Fig. 1, and Fig. 4 illustrates a connecting apparatus also according to the invention for connecting an open heating circuit with a closed heating circuit.

Referring to the drawings and initially to Figs. 1 and 2, there is illustrated a heating system according to the invention, indicated generally by the reference numeral 1 for space heating and for heating domestic water. The heating system 1 comprises an open heating circuit 3 and a closed heating circuit 5 connected together by a connecting system 7 also according to the invention which comprises apparatus 9 also according to the invention. The connecting system 7 and the apparatus 9 are described in detail below.

The open heating circuit 3 comprises a first heat source, which in this embodiment of the invention comprises a solid fuel stove 10, although the first heat source may be any suitable heat source, such as a back boiler of an open fireplace, an oil fired or a gas fired boiler/burner unit, a condensing boiler or the like. In this embodiment of the invention the open heating circuit 3 is a gravity fed heating circuit which comprises a flow pipe 12 for receiving flow first heat transfer fluid which has been heated by the solid fuel stove 10 and delivered from the solid fuel stove 10 through a flow outlet port 14. The first heat transfer fluid in this embodiment of the invention is water.

The flow pipe 12 connects the flow outlet port 14 of the solid fuel stove 10 to a flow inlet port 15 of a heat leaking means, which in this embodiment of the invention comprises a primary coil 16 which is located within a buffer tank 18, which in this case is provided by an indirect domestic hot water tank.

A secondary coil 20 also located in the buffer tank 18 is connected into the closed heating circuit 5 as will be described below, so that the first heat transfer fluid of the open heating circuit 3 is separated from second heat transfer fluid, which is also water, of the closed heating circuit 5.

A return pipe 22 connected to a return outlet port 23 from the primary coil 16 of the buffer tank 18 returns return first heat transfer fluid from the primary coil 16 to a return inlet port 25 of the solid fuel stove 10 as will be described below.

The open heating circuit 3 is pressurised from a header tank 27 of the first heat transfer fluid, which is connected into the flow pipe 12 through a feed pipe 28. A heat lock bend 29 is located in the feed pipe 28 in order to prevent the first heat transfer fluid being urged upwardly through the feed pipe 28 into the header tank 27. An expansion pipe 30 extending from the flow pipe 12 provides for expansion of the first heat transfer fluid in the open heating circuit 3, and the expansion pipe 30 terminates in an expansion outlet 33 located above the header tank 27 so that first heat transfer fluid resulting from expansion of the first heat transfer fluid in the open heating circuit 3 is returned to the header tank 27.

A spring loaded non-return valve 36 connects the expansion pipe 30 to the feed pipe 28 at a location intermediate the heat lock bend 29 and the flow pipe 12. The spring loaded non-return valve 36 is configured to permit normal flow between the expansion pipe 30 and the feed pipe 28, and to prevent flow from the feed pipe 28 to the expansion pipe 30 unless the pressure in the feed pipe 28 exceeds the pressure in the expansion pipe 30 by a predefined pressure differential. The non-return valve 36 is set so that on the pressure differential of the first heat transfer fluid exceeding the predefined pressure differential, a spring loaded valving element (not shown) in the non-return valve 36 is unseated to permit flow of the first heat transfer fluid from the feed pipe 28 to the expansion pipe 30. A manually operated valve 31 is provided for facilitating isolating the open heating circuit 3 from the header tank 27 for maintenance or other purposes.

Turning now to the closed heating circuit 5, the closed heating circuit 5 comprises a second heat source, in this embodiment of the invention a gas or oil fired burner/boiler unit 32 having a flow outlet port 34 connected by a flow pipe 35 to a flow inlet port 37 of a null point manifold 38 for delivering heated flow second heat transfer fluid from the burner/boiler unit 32 to the manifold 38. A return inlet port 40 to the burner/boiler unit 32 is connected by a return pipe 42 to a return outlet port 44 from the manifold 38. Two heating circuits 45 and 46 are provided from the manifold 38, with each heating circuit 45 and 46 comprising a plurality of space heating radiators (not shown) for heating respective zones of a building. Each heating circuit 45 and 46 comprises a flow pipe 47 and a return pipe 48, which are connected to corresponding flow and return ports 50 and 51 of the manifold 38. Circulating pumps 52 in the flow pipes 47 circulate the second heat transfer fluid from the manifold 38 through the respective heating circuits 45 and 46.

The secondary coil 20 of the buffer tank 18 is connected to the manifold 38 by a flow pipe 54 and a return pipe 55. The flow pipe 54 is connected between a flow outlet port 57 of the manifold 38 and a flow inlet port 58 of the secondary coil 20. The return pipe 55 connects a return outlet port 59 from the secondary coil 20 to a return inlet port 60 to the manifold 38. A circulating pump 62 in the flow pipe 54 circulates the second heat transfer fluid through the secondary coil 20 from the manifold 38. A non-return valve 64 is located in the flow pipe 54 in order to avoid any danger of reverse flow through the secondary coil 20.

Manual valves 65 are located in the return pipes 48 and 55 of the heating circuits 45 and 46 and of the secondary coil 20 in order to permit isolation of the respective heating circuits 45 and 46 and the secondary coil 20 from the manifold 38. Nonreturn valves 67 are also located in the return pipes 48 of the heating circuits 45 and in order to prevent reverse flow of the second heat transfer fluid through the heating circuits 45 and 46.

A pressurising element (not shown) is connected to the manifold 38 by a connecting pipe 68 for pressurising the second heat transfer fluid in the closed heating circuit 5. The pressurising element may be any suitable pressurising element, for example, a pressurising vessel having a diaphragm located therein dividing the vessel into first and second chambers with the first chamber being provided for the second heat transfer fluid, and connected to the manifold 5 by the connecting pipe 68, and the second chamber being pressurised by a suitable pressurising gas, for example, air. Such pressurising vessels will be well known to those skilled in the art.

Turning now to the connecting system 7 and the apparatus 9 for connecting the open heating circuit 3 to the closed heating circuit 5, the connecting system 7 comprises a heat exchanger 70, which in this embodiment of the invention comprises a plate heat exchanger for cooling the first heat transfer fluid in the open heating circuit 3 in the event of the first heat transfer fluid of the open heating circuit 3 rising to a first predefined temperature, which in this embodiment of the invention is approximately 65°C. A first temperature monitoring means comprising a first pipe thermostat 72 is mounted on the flow pipe 12 adjacent the flow outlet port 14 of the solid fuel stove 10 for monitoring the temperature of the first heat transfer fluid in the flow pipe 12. The heat exchanger 70 is located in a bypass circuit 75 which bypasses the primary coil 16 in the buffer tank 18. A first pumping means, namely, a first electrically powered pump 73 is located in series with the heat exchanger 70 in the bypass circuit 75 for pumping the first heat transfer fluid through the heat exchanger 70 in response to the temperature of the first heat transfer fluid monitored by the first pipe thermostat 72 rising to the first predefined temperature of approximately 65°C.

The first pump 73 is connected between the flow pipe 12 and a first flow inlet port 76 ,of the heat exchanger 70. A first return outlet port 78 from the heat exchanger 70 is connected to a means for drawing return first heat transfer fluid through and from the primary coil 16 of the domestic hot water tank 18. in this embodiment of the invention the means for drawing the first heat transfer fluid through and from the primary coil 16 comprises a venturi element, which in this embodiment of the invention comprises a venturi injector Tee connector element 80 through which return first heat transfer fluid is returned from the first return outlet port 78 of the heat exchanger 70 to the return inlet port 25 of the solid fuel stove 10 through a return pipe 99. A jet outlet 81 in the venturi injector Tee connector element 80 produces a low pressure in a chamber 82 of the venturi injector Tee connector element 80. A low pressure connection, namely, a low pressure inlet port 84 to the low pressure chamber 82 of the venture injector Tee connector element 80 is connected to the return pipe 22 from the return outlet port 23 from the primary coil 16 for drawing the first heat transfer fluid through and from the primary coil 16, and in turn for returning the first heat transfer fluid from the primary coil 16 to the return inlet port 25 of the solid fuel stove 10 when the first pump 73 is pumping the first heat transfer fluid through the heat exchanger 70. A non-return valve 85 between the first return outlet port 78 of the heat exchanger 70 prevents reverse flow of the first heat transfer fluid through the bypass circuit 75.

A second return inlet port 87 and a second flow outlet port 88 to and from the heat exchanger 70 accommodate flow of the second heat transfer fluid of the closed heating circuit 5 through the heat exchanger 70 for transferring heat from the first heat transfer fluid to the second heat transfer fluid, with the first and second heat transfer fluids separated from each other in the heat exchanger 70.

A second pumping means, namely, a second electrically powered pump 90 connected in series with the heat exchanger 70 is responsive to the temperature of the first heat transfer fluid in the flow pipe 12 of the open heating circuit 3, which is monitored by the first pipe thermostat 72, rising to the first predefined temperature of approximately 65°C, for circulating the second heat transfer fluid through the heat exchanger 70, so that heat is transferred from the first heat transfer fluid to the second heat transfer fluid in the heat exchanger 70.

A return pipe 120 connected between a return outlet port 121 from the manifold 38 and a return inlet port 122 of the second pump 90 accommodates return second heat transfer fluid from the manifold 38 to the second pump 90. A flow pipe 125 from the second flow outlet port 88 of the heat exchanger 70 to a flow inlet port 126 of the manifold 38 accommodates flow of second heat transfer fluid from the heat exchanger 70 to the manifold 38.

In use, with the heating system 1 comprising the open heating circuit 3 connected to the closed heating circuit 5 by the connecting system 7, the heating system 1 is ready for use. When the first heat transfer fluid in the open heating circuit 3 is being heated by the solid fuel stove 10 and when the second heat transfer fluid in the closed heating circuit 5 is heated by the burner/boiler unit 32, the first and second pumps 73 and 90 are deactivated, and the first heat transfer fluid is circulated through the primary coil 16 in the buffer tank 18, In the event of the temperature of the first heat transfer fluid which is monitored by the first pipe thermostat 72 rising to the first predefined temperature of approximately 65°C, the first and second pumps 73 and 90 are operated for pumping the first and second heat transfer fluids through the heat exchanger 70 for transferring heat from the first heat transfer fluid to the second heat transfer fluid. The first and second pumps 73 and 90 remain activated until the temperature monitored by the first pipe thermostat 72 falls below the first predefined temperature of approximately 65°C, at which stage the first and second pumps are deactivated.

As the first pump 73 is pumping the first heat transfer fluid through the heat exchanger 70, the venturi injector Tee connector element 80 draws return first heat transfer fluid through and from the primary coil 16, thereby ensuring that some of the first heat transfer fluid continues to flow through the primary coil 16 while the first pump 73 is pumping the remainder of the first heat transfer fluid through the heat exchanger 70 for cooling thereof.

Referring now to Fig. 2, there is illustrated apparatus according to the invention, indicated generally by the reference numeral 93, which forms a part of the connecting system 7 of Fig. 1, and is constructed to be sold as a single integral unit. The apparatus 93 comprises a housing 94 which is illustrated in broken lines in Fig. only. Located within the housing 94 is the heat exchanger 70 and the first and second pumps 73 and 90 connected as described with reference to Fig. 1. The venturi injector Tee connector element 80 is also located within the housing 94 connected to the first return outlet port 78 from the heat exchanger 70 through the non-return valve 85. A first flow inlet port 95 and a first return outlet port 96 extend from the apparatus 93 externally of the housing 94 for facilitating connecting of the apparatus 93 into the open heating circuit 3. The first flow inlet port 95 is connected to an inlet port 97 of the first pump 73, and is configured for connecting to the flow pipe 12 of the open heating circuit 3. The first return outlet port 96 is formed by an outlet port 98 of the venturi element 80 and is configured for connecting to the return pipe 99 of the open heating circuit 3.

A second return inlet port 100 and second flow outlet port 101, respectively, are provided to the apparatus 93 externally of the housing 94. The second return inlet port 100 is connected to an inlet port 103 of the second pump 90, and is configured for connecting to the return pipe 120 of the closed heating circuit 5. The second flow outlet port 101 is connected to the second flow outlet port 88 of the heat exchanger 70 and is configured for connecting to the flow pipe 125 of the closed heating circuit 5. A low pressure port 105 of the apparatus 93 is located externally of the housing 94 and is formed by the low pressure inlet port of the venturi element 80, which is configured for connecting to the return pipe 22 from the primary coil 16 of the buffer tank 18.

Referring now to Fig. 3, there is illustrated apparatus 110 also according to the invention, which may also form a part of the connecting system 7 for connecting the open heating circuit 3 to the closed heating circuit 5. In this embodiment of the invention the apparatus 110 is substantially similar to the apparatus 93 and similar components are identified by the same reference numerals. The main difference between the apparatus 110 and the apparatus 93 is that the apparatus 110 also comprises a portion 111 of the flow pipe 12 of the open heating system 3. In this embodiment of the invention the first flow inlet port 95 which is also located externally of the housing 94 is formed by an inlet port to the portion 111 of the flow pipe 12 extending through the housing 94. A third flow outlet port 112 is provided at the opposite end of the portion 111 of the flow pipe 12 and is configured for connecting into the portion of the flow pipe 12 which extends to the primary coil 16. The apparatus 110 also includes a portion 114 of the feed pipe 28 as well as the heat lock bend 29 and the manual valve 31. The apparatus 110 also includes a portion 116 of the expansion pipe 30 as well as the spring loaded non-return valve 36. Additionally, the apparatus 110 includes an inlet port 118 and an outlet port 119, both of which are located externally of the housing 94. The inlet port 119 is connected to the manual valve 31 and is configured for connecting to the portion of the feed pipe 28 extending to the header tank 27. The outlet port 119 is located at the end of the portion of the expansion pipe 116 and is configured for connecting to the remaining portion of the expansion pipe 30 which extends upwardly and terminates in the outlet 33 above the header tank 27. In the apparatus 110 the heat lock bend 29 and the non-return valve 36 are also located within the housing 94. Otherwise, the apparatus 110 is similar to the apparatus 93.

In use, the apparatus 93 and 110 are used for connecting the open heating circuit 3 to the closed heating circuit 5, and the various external ports of the apparatus 93 and the apparatus 111 are connected to appropriate ones of the pipes of the respective systems as discussed above.

Referring now to Fig. 4 there is illustrated connecting apparatus according to another embodiment of the invention indicated generally by the reference numeral 130 for connecting an open heating circuit, similar to the open heating circuit 3 with a closed heating circuit, similar to the closed heating circuit 5. The open and closed heating circuits to be connected by the connecting apparatus 130 will be assumed to be similar to the open and closed heating circuits 3 and 5, and reference to connecting points and other components of the open and closed heating circuits, will be referred to by the same reference numerals as those connecting points and components of the open and closed heating circuits 3 and 5. In this embodiment of the invention the first pump 73, is connected between the outlet port 78 of the heat exchanger 70 and the inlet port 146 of the venturi injector Tee connector element 80 from which the jet outlet 81 extends for producing the low pressure chamber 82. Otherwise the arrangement of the heat exchanger 70, the first pump 73 and the venturi injector Tee connector element 80 in the connecting apparatus 130 is similar to the connections of the connecting system 9 of the heating system 1.

In this embodiment of the invention the apparatus 130 comprises a housing 132 within which the heat exchanger 70, the first pump 73, the second pump 90 and the venturi injector Tee connector element 80 are located. A first inlet port 134 for connecting to the flow outlet port 14 of the solid fuel stove 10 extends externally of the housing 132. A first outlet port 135 extending outwardly from the housing 132 is provided for connecting to the return inlet port 25 of the stove 10. A second inlet port 136 extends from the housing 132 for connecting to the port 121 of the manifold 38, while a second outlet port 137 extending from the housing 132 is provided for connecting to the port 126 of the manifold 38. A third inlet port 138 extends from the housing 132 for connecting to the return outlet port 23 of the primary coil 16 of the buffer tank 18. A third outlet port 139 extending from the housing 132 is provided for connecting to the flow inlet port 15 of the primary coil 16 of the buffer tank 18.

As can be seen from Fig. 4 the first inlet port 134 is connected directly to the third outlet port 139 by a connecting pipe 140 for facilitating the flow of the first heat transfer fluid from the flow outlet port 14 of the stove 10 to the flow inlet port 15 of the primary coil 16 of the buffer tank 18. A connection 141 is teed off from the connecting pipe 140 through a connecting Tee connector 142 for connecting the connecting pipe 140, and in turn the flow outlet port 14 of the stove 10 to the inlet port 76 of the heat exchanger 70. A connecting pipe 144 connects the outlet port 78 of the heat exchanger 70 to the first pump 73, which in turn is connected through a connecting pipe 145 to the inlet port 146 of the venturi injector Tee connector element 80 from which the jet outlet 81 extend into the low pressure chamber 82 of the venturi injector Tee connector element 80. The third inlet port 138 is connected to the low pressure inlet port 84 of the venturi injector Tee connector element 80, while the third port 147 of the venturi injector Tee connector element 80 is connected to the first outlet port 135 through a connecting pipe 149. The second inlet port 136 is connected to the second pump 90 which in turn is connected to the inlet port 87 of the heat exchanger 70. The outlet port 88 of the heat exchanger 70 is connected to the second outlet port 137.

In use, the first inlet and outlet ports 134 and 135 of the connecting apparatus 130 are connected to the flow outlet port 14 and a return inlet port 25, respectively, of the solid fuel stove 10 of the open heating circuit 3. The second inlet port 136 and the second outlet port 137 of the connecting apparatus 130 are connected respectively to the ports 121 and 126 of the manifold 38 of the closed heating circuit 5. The third inlet and outlet ports 138 and 139 are connected to the return outlet port 23 and the flow inlet port 15, respectively of the primary coil 16 of the buffer tank 18. With the open heating circuit 3 and the closed heating circuit 5 connected together with the connecting apparatus 130 as described above, the open heating circuit 3 and the closed heating circuit 5 are operated as already described with reference to Fig. 1.

While the open heating circuit 3 has been described as being provided for heating domestic hot water only, it will be readily apparent to those skilled in the art that the open heating circuit may also comprise one or more heating circuits, each of which would comprise a plurality of space heating radiators for heating respective zones of a building. Typically, circulating pumps would be provided in each of the heating circuits of the closed heating circuit 3. It will also be appreciated that the open heating circuit may comprise a plurality of heat sources, which would typically be connected together through a null point manifold into which the respective heating circuits would also be connected.

It will also be appreciated that the closed heating circuit 5 may comprise more than one heat source, for example, a plurality of boiler/burner units, each of which would be connected into the closed heating circuit 5 through the null point manifold 38.

It is envisaged that while the heat leaking means has been described as an indirect buffer tank for producing domestic hot water, any other suitable heat leaking means or heat sinking means may be provided, for example, the heat leaking means may be provided as one or a bank of space heating radiators, or one or more air heat exchangers.

While the buffer tank has been described as comprising a domestic hot water tank, while this is advantageous, it is not necessary that the buffer tank be provided as a domestic hot water tank. In certain cases, it is envisaged that the buffer tank may be provided solely for the purpose of coupling the open heating circuit to the closed heating circuit, and in which case, it is envisaged that the buffer tank would comprise only one coil, to which either the closed heating circuit or the open heating circuit would be connected, and the other one of the closed heating circuit and the open heating circuit would be connected directly into the buffer tank so that heat could be exchanged between the first and second heat transfer fluids of the open and closed heating circuits, respectively, with the first and second heat transfer fluids separated from each other in the buffer tank.

While the first temperature monitoring means has been described as a pipe thermostat, any suitable first temperature monitoring means may be provided for monitoring the temperature of the first heat transfer fluid in the open heating circuit.

It will also be appreciated that instead of locating the first pipe thermostat on the flow pipe 12 from the solid fuel stove 10, the first temperature monitoring means, be it a pipe thermostat or any other suitable temperature monitoring means may be provided on the return pipe 22 for monitoring the return temperature of the first heat transfer fluid. However, in cases where the temperature of the return first heat transfer fluid is being measured, the first predefined temperature instead of being 65°C would be 10°C less at 55°C.

Claims (72)

Claims

1. A method for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid in the open heating circuit, to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid in the closed heating circuit, the method comprising connecting the open heating circuit into a heat leaking means, connecting the open heating circuit to a heat exchanger and connecting the closed heating circuit to the heat exchanger with the first and second heat transfer fluids separated from each other for transferring heat from the first heat transfer fluid to the second heat transfer fluid, locating a first pumping means configured to pump the first heat transfer fluid through the heat exchanger, locating a means in the open heating circuit for drawing the first heat transfer fluid through the heat leaking means in response to the first pumping means pumping the first heat transfer fluid through the heat exchanger.

2. A method as claimed in Claim 1 in which the means for drawing the first heat transfer fluid through the heat leaking means comprises a venturi element through which the first heat transfer fluid pumped through the heat exchanger is delivered.

3. A method as claimed in Claim 2 in which the venturi element is located between the heat exchanger and the first heat source, so that the first heat transfer fluid is delivered through the venturi element after the first heat transfer fluid has passed through the heat exchanger.

4. A method as claimed in Claim 2 or 3 in which the venturi element is configured for drawing the first heat transfer fluid from the heat leaking means to the first heat source.

5. A method as claimed in any preceding claim in which the first pumping means is located in series with the heat exchanger and the first heat source.

6. A method as claimed in any preceding claim in which the first pumping means and the heat exchanger are located in a bypass circuit, the bypass circuit bypassing the heat leaking means.

7. As method as claimed in any preceding claim in which the first pumping means is responsive to the temperature of the first heat transfer fluid from the first heat source rising to a first predefined temperature for pumping the first heat transfer fluid through the heat exchanger.

8. A method as claimed in Claim 7 in which the first predefined temperature is greater than 55°C.

9. A method as claimed in Claim 7 or 8 in which the first predefined temperature is greater than 60°C.

10. A method as claimed in any of Claims 7 to 9 in which the first predefined temperature is approximately 65°C.

11. A method as claimed in any preceding claim in which the first pumping means comprises a first electrically powered pump.

12. A method as claimed in any preceding claim in which a second pumping means is provided for pumping the second heat transfer fluid through the heat exchanger.

13. A method as claimed in Claim 12 in which the second pumping means is located in series with the heat exchanger.

14. A method as claimed in Claim 12 or 13 in which the second pumping means is responsive to the temperature of the first heat transfer fluid from the first heat source rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat transfer fluid to the second heat transfer fluid.

15. A method as claimed in any of Claims 12 to 14 in which the second pumping means comprises a second electrically powered pump.

16. A method as claimed in any preceding claim in which the heat leaking means comprises a buffer tank. 5

17. A method as claimed in Claim 16 in which the buffer tank comprises an indirect buffer tank.

18. A method as claimed in Claim 16 or 17 in which the heat leaking means comprises a primary heat exchange coil located in the buffer tank.

19. A method as claimed in any of Claims 16 to 18 in which the open heating circuit is connected to the one of the buffer tank and the primary heat exchange coil in the indirect buffer tank so that the first heat transfer fluid is circulated from the first heat source through the one of the buffer tank and the primary heat exchange coil 15 located in the buffer tank.

20. A method as claimed in any of Claims 16 to 19 in which the closed heating circuit is connected to a secondary heat exchange coil in the buffer tank. 20

21. A method as claimed in any of Claims 16 to 20 in which the closed heating circuit is connected to the one of the buffer tank or the secondary heat exchange coil in the buffer tank so that the second heat transfer fluid is circulated through the one of the buffer tank and the secondary heat exchange coil of the buffer tank from the closed heating circuit.

22. A method as claimed in any of Claims 16 to 21 in which the buffer tank comprises a buffer tank for heating a domestic hot water supply.

23. A method as claimed in any preceding claim in which the open heating circuit 30 is connected to a header tank by a feed pipe.

24. A method as claimed in Claim 23 in which a heat lock bend is located in the feed pipe to prevent back-feed of the first heat transfer fluid from the open heating circuit to the header tank.

25. A method as claimed in any preceding claim in which an expansion pipe is connected to the open heating circuit for accommodating expansion of the first heat transfer fluid in the open heating circuit.

26. A method as claimed in Claim 25 in which the feed pipe is coupled to the expansion pipe at a location intermediate the heat lock bend and the open heating circuit.

27. A method as claimed in Claim 25 or 26 in which the feed pipe is coupled to the expansion pipe through a non-return valve.

28. A method as claimed in any of Claims 25 to 27 in which the feed pipe is coupled to the expansion pipe through a spring loaded non-return valve.

29. A method as claimed in Claim 27 or 28 in which the non-return valve is configured to prevent flow of the first heat transfer fluid from the feed pipe to the expansion pipe.

30. A method as claimed in any preceding claim in which the second heat transfer fluid in the closed heating circuit is pressurised by a pressurising element.

31. A method as claimed in any preceding claim in which the closed heating circuit is a fully sealed heating circuit.

32. A connecting system for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid, to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the connecting system comprising a means for connecting the open heating circuit to a heat leaking means, a heat exchanger for connecting the open heating circuit and the closed heating circuit thereto with the first and second heat transfer fluids separated from each other for transferring heat from the first heat transfer fluid to the second heat transfer fluid, a first pumping means configured to pump the first heat transfer fluid through the heat exchanger, and a means for locating in the open heating circuit for drawing the first heat transfer fluid through the heat leaking means in response to the first pumping means pumping the first heat transfer fluid through the heat exchanger.

33. A connecting system as claimed in Claim 32 in which the means for drawing the first heat transfer fluid through the heat leaking means comprises a venturi element, the venturi element being configured for iocating between the heat exchanger and the first heat source for accommodating the first heat transfer fluid from the heat exchanger to the first heat source, and the venturi element having a low pressure port for connecting to a return outlet port from the heat leaking means for receiving return first heat transfer fluid from the heat leaking means for delivery to the first heat source.

34. A connecting system as claimed in Claim 32 or 33 in which the first pumping means is located in series with the heat exchanger and the first heat source.

35. A connecting system as claimed in any of Claims 32 to 34 in which the first pumping means and the heat exchanger are located in a bypass circuit.

36. A connecting system as claimed in Claim 35 in which the bypass circuit is configured to bypass the heat leaking means.

37. A connecting system as claimed in any of Claims 32 to 36 in which the first pumping means is responsive to the temperature of the first heat transfer fluid rising to a first predefined temperature for circulating the first heat transfer fluid through the heat exchanger.

38. A connecting system as claimed in Claim 37 in which the first predefined temperature is greater than 55°C.

39. A connecting system as claimed in Claim 37 or 38 in which the first predefined temperature is greater than 60°C.

40. A connecting system as claimed in any of Claims 37 to 39 in which the first predefined temperature is approximately 65°C.

41. A connecting system as claimed in any of Claims 32 to 40 in which the first pumping means comprises a first electrically powered pump.

42. A connecting system as claimed in any of Claims 32 to 41 in which a second pumping means is provided for pumping the second heat transfer fluid through the heat exchanger.

43. A connecting system as claimed in Claim 42 in which the second pumping means is located in series with the heat exchanger.

44. A connecting system as claimed in Claim 42 or 43 in which the second pumping means is responsive to the temperature of the first heat transfer fluid rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat exchange fluid to the second heat transfer fluid.

45. A connecting system as claimed in any of Claims 32 to 44 in which the heat leaking means comprises a buffer tank.

46. A connecting system as claimed in Claim 45 in which the heat leaking means comprises an indirect buffer tank.

47. A connecting system as claimed in Claim 45 or 46 in which, the heat leaking means comprises a primary heat exchange coil located in the buffer tank.

48. A connecting system as claimed in any of Claims 45 to 47 in which the open heating circuit is connected to the one of the buffer tank and the primary heat exchange coil in the indirect buffer tank so that the first heat transfer fluid is circulated from the first heat source through the one of the buffer tank and the primary heat exchange coil located in the buffer tank.

49. A connecting system as claimed in any of Claims 45 to 48 in which the closed heating circuit is connected to a secondary heat exchange coil in the buffer tank.

50. A connecting system as claimed in any of Claims 45 to 49 in which the closed heating circuit is connected to the one of the buffer tank or the secondary heat exchange coil in the buffer tank so that the second heat transfer fluid is circulated through the one of the buffer tank and the secondary heat exchange coil of the buffer tank from the closed heating circuit.

51. A connecting system as claimed in any of Claims 45 to 50 in which the buffer tank comprises a buffer tank for heating a domestic hot water supply.

52. A heating system comprising an open heating circuit comprising a first heat source for heating a first heat transfer fluid, and a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the open heating circuit being connected to the closed heating circuit by the connecting system as claimed in any of Claims 32 to 51, with the open heating circuit being connected to a heat leaking means, and the heat exchanger being connected to the open and closed heating circuits with the first and second heat transfer fluids separated from each other therein, and the means for drawing the first heat transfer fluid from the heat leaking means being located in the open heating circuit for delivering the first heat transfer fluid from the heat exchanger to the first heat source and for drawing return first heat transfer fluid from the heat leaking means and delivering the return first heat transfer fluid to the first heat source.

53. A heating system as claimed in Claim 52 in which the first pumping means of the connecting system is located in series with the heat exchanger and the first heat source.

54. A heating system as claimed in Claim 52 or 53 in which the first pumping means and the heat exchanger are located in a bypass circuit, and the bypass circuit is located to bypass the heat leaking means.

55. A heating system as claimed in any of Claims 52 to 54 in which a first temperature monitoring means is provided for monitoring the temperature of flow heat transfer fluid from the first heat source.

56. A heating system as claimed in Claim 55 in which the first pumping means is responsive to the temperature monitored by the first temperature monitoring means rising to the first predefined temperature for pumping the first heat transfer fluid through the heat exchanger.

57. A heating system as claimed in any of Claims 52 to 56 in which the second pumping means of the connecting system is connected in series with the heat exchanger.

58. A heating system as claimed in any of Claims 52 to 57 in which the second pumping means is configured to draw return second heat transfer fluid from the closed heating circuit and to deliver the return second heat transfer fluid to the heat exchanger.

59. A heating system as claimed in any of Claims 52 to 58 in which the second pumping means is configured to pump the second heat transfer fluid through the heat exchanger and to return the second heat transfer fluid from the heat exchanger to the closed heating circuit.

60. A heating system as claimed in any of Claims 52 to 59 in which the second pumping means pumps the second heat transfer fluid between the heat exchanger and a null point manifold of the closed heating circuit.

61. A heating system as claimed in any of Claims 55 to 60 in which the second pumping means is responsive to the temperature monitored by the first temperature monitoring means rising to the first predefined temperature for pumping the second heat transfer fluid through the heat exchanger to transfer heat from the first heat transfer fluid to the second heat transfer fluid.

62. Apparatus for coupling an open heating circuit comprising a first heat source for heating a first heat transfer fluid to a closed heating circuit comprising a second heat source for heating a second heat transfer fluid, the apparatus comprising a heat exchanger for connecting to the open heating circuit and the closed heating circuit for transferring heat from the first heat transfer fluid to the second heat transfer fluid with the first and second heat transfer fluids separated from each other, a means for connecting the open heating circuit to a heat leaking means, a first pumping means for pumping the first heat transfer fluid through the heat exchanger, a means for drawing return first heat transfer fluid from the heat leaking means for delivery to the first heat source, the means for drawing the first heat transfer fluid from the heat leaking means being connected to the heat exchanger and configured for connecting to a return inlet port of the first heat source, and a second pumping means for pumping the second heat transfer fluid through the heat exchanger for transferring heat from the first heat transfer fluid to the second heat transfer fluid, the heat exchanger, the first and second pumping means, and the means for drawing the first heat transfer fluid from the heat leaking means being provided as an integral unit, and comprising a first inlet port and a first outlet port for connecting the apparatus into the open heating circuit, a second inlet port and a second outlet port for connecting the apparatus to the closed heating circuit, and a third inlet port and a third outlet port for connecting the apparatus to the heat leaking means.

63. Apparatus as claimed in Claim 62 in which the second pumping means and the heat exchanger are connected in series between the second inlet port and the second, outlet port.

64. Apparatus as claimed in Claim 62 or 63 in which the second pumping means is connected to the second inlet port and the heat exchanger is connected to the second outlet port.

65. Apparatus as claimed in any of Claims 62 to 64 in which the second inlet port is configured for connecting to a return supply of the second heat transfer fluid of the closed heating circuit, and the second outlet port is configured for connecting to a flow supply of the second heat transfer fluid of the closed heating circuit.

66. Apparatus as claimed in any of Claims 62 to 65 in which the first inlet port and the third outlet port are interconnected.

67. Apparatus as claimed in any of Claims 62 to 66 in which the first inlet port and the third outlet port are connected to the heat exchanger through a Teed connection between the first inlet port and the third outlet port.

68. Apparatus as claimed in any of Claims 62 to 67 in which the means for drawing return first heat transfer fluid from the heat leaking means comprises an injector Tee connector, the low pressure connection of the injector Tee connector being connected to the third inlet port.

69. Apparatus as claimed in Claim 68 in which the third inlet port is connected to the first outlet port through the injector Tee connector.

70. Apparatus as claimed in Claim 68 or 69 in which the heat exchanger, the first pumping means and the injector Tee connector are connected in series between the first inlet port and the first outlet port.

71. Apparatus as claimed in any of Claims 68 to 70 in which the third inlet port is connected to the first outlet port through the injector Tee connector, so that when the first pumping means is operational, return first heat transfer fluid is drawn in through the third inlet port through the injector Tee connector.

72. Apparatus as claimed in any of Claims 62 to 71 in which the first and second pumping means, the heat exchanger and the means for drawing the first heat transfer fluid from the heat leaking means are located in a housing, with the first, second and third inlet and outlet ports located exteriorly of the housing. F.F. GORMAN & CO.