GB2470117A

GB2470117A - Method and apparatus for detecting the flow of a fluid through a heat exchanger

Info

Publication number: GB2470117A
Application number: GB1007438A
Authority: GB
Inventors: Martin Robert Von Lintzgy
Original assignee: Tekelek Patents Ltd
Current assignee: Tekelek Patents Ltd
Priority date: 2009-05-01
Filing date: 2010-05-04
Publication date: 2010-11-10
Also published as: IE20100275A1; IES20090347A2; IE86374B1; GB201007438D0

Abstract

A method and apparatus for detecting the flow of a fluid through a heat exchanger is disclosed, comprising monitoring a temperature related to the temperature of the heat exchanger, and detecting a change in the monitored temperature indicative of a flow of the fluid through the heat exchanger. In a further aspect, a combination of a heat exchanger, a heat source or sink, and apparatus for monitoring the temperature of the heat exchanger is disclosed. The heat source or sink communicates with the heat exchanger for circulation of heat exchange medium between the heat exchanger and the source or sink. Preferably, the combination 1 comprises a boiler 2 for heating heat exchange water, a reservoir 3 for storing the heat exchange water and a heat exchanger 4. Domestic water may be supplied to the heat exchanger from an inlet pipe 14 through a water port 16, and heated domestic water delivered through a water outlet pipe 15. Preferably, a thermistor 20 is located on the inlet pipe adjacent the water inlet port of the heat exchanger and a control circuit 24 monitors signals from the thermistor and outputs activating signals to the boiler and a circulating pump 12.

Description

"A method and apparatus for detecting flow of a fluid through a heat exchanger" The present invention relates to a method and apparatus for detecting flow of a fluid through a heat exchanger, and the invention also relates to a combination of a heat exchanger and one of a heat source and a heat sink.

Domestic heating systems which include the combination of a boiler and a reservoir of high temperature water are known. In general, in such combinations the boiler is operated at a temperature for raising the temperature of water in the high io temperature reservoir to a temperature just below boiling point, and typically, at a temperature of the order of 90°C to 95°C. A heat exchanger is provided for exchanging heat between the high temperature water in the high temperature reservoir and flow water, which typically, provides domestic hot water, for washing, baths, showers and the like. In order that such combination boilers and high temperature reservoirs operate efficiently, in general, the capacity of the high temperature water reservoir is relatively low, and typically, does not exceed 50 litres.

Thus, it is therefore essential that the boiler be activated as soon as flow water commences to be drawn through the heat exchanger. Otherwise, as the flow water commences to flow, the temperature of the water in the high temperature reservoir will drop relatively rapidly, and consequently the temperature of the domestic hot **** water flow * * ****

S

* .SSSS * 5 Known methods and apparatus for detecting flow of flow water through such heat exchangers requires the presence of a flow detector, which typically comprises a mechanical paddle flow switch extending into a flow pipe either upstream or downstream of the heat exchanger for monitoring flow of the flow water through the : .. heat exchanger. On the flow detector detecting flow of the flow water, a signal is **** * transmitted to a control circuit which activates the boiler in order to minimise the rate of fall in the temperature of the water in the high temperature reservoir. While such methods using such flow detectors do detect the flow of flow water, flow detectors, being mechanical, are relatively expensive and prone to failure.

Additionally, such mechanical flow detectors as well as being responsive to normal draw-off of water are also responsive to the lowest flow rates, such as the flow rate resulting from a dripping tap. Thus, in the event of a dripping tap, the boiler is activated, and the boiler is also activated in the event of domestic water being drawn off for a relatively short period, and in particular during short periods where the volume of water draw-off would have little or no effect on the temperature of the water in the high temperature water reservoir. In the latter case, the boiler may only be operated for a few seconds, for example, ten to fifteen seconds.

The operation of a boiler for such short periods of the order of ten to fifteen seconds results in a particularly serious problem. Burners of boilers, in general, when activated initially go through a start-up sequence of cycles which includes a purging/priming/ignition/flame detection sequence. This sequence takes approximately twenty seconds to thirty seconds, and if the boiler is deactivated during the start-up sequence, and particularly, during the initial part of the start-up sequence, a build-up of carbon deposits results in the boiler, as well as fuel wastage.

This is undesirable, and any build-up of carbon deposits in a boiler results in inefficient operation of the boiler, and requires frequent and costly servicing of the boiler.

There is therefore a need for a method and apparatus for detecting flow of water through a heat exchanger, and there is also a need for a combination of a boiler or * other heat source or heat sink and a heat exchanger which addresses the problems

of the prior art systems. S..

* The present invention is directed towards providing a method and apparatus for : ,* detecting flow of a fluid through a heat exchanger, as well as a combination of a heat *S.S * exchanger and one of a heat source and a heat sink.

According to the invention there is provided a method for detecting flow of a fluid through a heat exchanger, the method comprising monitoring a temperature indicative of the temperature of the heat exchanger, and detecting a change in the temperature thereof indicative of flow of the fluid through the heat exchanger.

In one embodiment of the invention the temperature of the heat exchanger is monitored adjacent a fluid inlet port to the heat exchanger for accommodating the s fluid into the heat exchanger. Preferably, the temperature of the heat exchanger adjacent the fluid inlet port is monitored by monitoring the temperature of an inlet pipe adjacent the fluid inlet port delivering the fluid to the heat exchanger through the fluid inlet port.

Preferably, the temperature of the heat exchanger is monitored by a temperature sensing means.

In one embodiment of the invention the temperature sensing means comprises a temperature sensor. In another embodiment of the invention the temperature is sensing means comprises a thermistor.

Preferably, an activating signal is produced in response to a change in the temperature of the heat exchanger being indicative of flow of the fluid therethrough.

Preferably, the activating signal is produced in response to the change in the temperature of the heat exchanger being indicative of a change in the temperature of *. the fluid adjacent the fluid inlet port to the heat exchanger.

S

S.....

* * In one embodiment of the invention the activating signal is produced in response to the change in temperature of the heat exchanger being in the range of 0.1°C to 2°C.

Preferably, the activating signal is produced in response to the change in SI* * temperature of the heat exchanger being in the range of 0.2°C to 1°C.

: ,** Advantageously, the activating signal is produced in response to the change in * temperature of the heat exchanger being in the order of 0.5°C. *S

S

In another embodiment of the invention the fluid is water, and in another embodiment of the invention the fluid is domestic water.

In one embodiment of the invention the heat exchange medium is heat exchange water.

In a further embodiment of the invention the heat exchanger is adapted for transferring heat from the heat exchange medium into the fluid for heating thereof.

The invention also provides apparatus for detecting flow of fluid through a heat exchanger, the apparatus comprising a temperature sensing means for detecting a temperature indicative of the temperature of the heat exchanger and for producing a signal indicative of the temperature of the heat exchanger, and a monitoring means for monitoring the signal from the temperature sensing means, the monitoring means being responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger indicative of flow of fluid through the heat exchanger for producing an activating signal.

In one embodiment of the invention the temperature sensing means is adapted for mounting adjacent a fluid inlet port of the heat exchanger through which the fluid is delivered into the heat exchanger. Preferably, the temperature sensing means is adapted for mounting on an inlet pipe adjacent the fluid inlet port for delivering the fluid into the heat exchanger through the fluid inlet port.

Preferably, the temperature sensing means comprises a temperature sensor.

* Advantageously, the temperature sensing means comprises a thermistor. * *. * * S

Preferably, the monitoring means comprises a microcontroller. *S.

S

: ,* Preferably, the activating signal is adapted for applying to one of a heat source and a S...

* heat sink for activating the one of the heat source and the heat sink to one of heat *S.

and cool the heat exchange medium for supplying to the heat exchanger.

Advantageously, the activating signal is adapted for applying to a circulating means for circulating the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.

In one embodiment of the invention a reservoir is provided for storing the heat exchange medium, and the circulating means circulates the heat exchange medium sequentially through the one of the heat source and the heat sink, the reservoir and the heat exchanger.

In another embodiment of the invention the one of the heat source and the heat sink is a boiler.

Preferably, the boiler comprises a burner, and the activating signal is adapted for applying to the burner for activating thereof.

Additionally the invention provides in combination a heat exchanger and one of a heat source and a heat sink communicating with the heat exchanger for circulation of a heat exchange medium between the heat exchanger and the one of the heat source and the heat sink, and apparatus according to the invention for detecting flow of fluid through the heat exchanger.

Further the invention provides in combination a heat exchanger and one of a heat source and a heat sink communicating with the heat exchanger for circulation of heat *..S exchange medium between the heat exchanger and the one of the heat source and * the heat sink, and apparatus for monitoring the temperature of the heat exchanger for detecting flow of a fluid through the heat exchanger, the apparatus comprising a temperature sensing means for detecting a temperature indicative of the * temperature of the heat exchanger and for producing a signal indicative of the : **** temperature of the heat exchanger, and a monitoring means for monitoring the S..

:. signal from the temperature sensing means, the monitoring means being responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger indicative of fluid flow through the heat exchanger for producing an activating signal and applying the activating signal to the one of the heat source and the heat sink for activating thereof.

Preferably, a circulating means is coupled to the heat exchanger and the one of the heat source and the heat sink for circulating the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.

Advantageously, the activating signal produced by the monitoring means is applied to the circulating means for activating thereof to circulate the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.

In one embodiment of the invention a storing means is provided for the heat exchange medium, the storing medium being coupled to the heat exchanger and the one of the heat source and the heat sink, so that the heat exchange medium is circulated sequentially through the one of the heat source and the heat sink, the storing means and the heat exchanger. Preferably, the circulating means is adapted for circulating the heat exchange medium sequentially through the one of the heat source and the heat sink, the storing means and the heat exchanger.

In one embodiment of the invention the heat exchange medium is heat exchange water, and the storing means comprises a reservoir for storing the heat exchange water. Preferably, the capacity of the reservoir lies in the range of 5 litres to 20 litres.

Advantageously, the capacity of the reservoir lies in the range of 10 litres to 15 litres.

Ideally, the capacity of the reservoir is in the order of 12 litres.

* In another embodiment of the invention the temperature sensing means is located adjacent a fluid inlet port to the heat exchanger through which the fluid is accommodated into the heat exchanger. Preferably, the temperature sensing *..

means is adapted for mounting on an inlet pipe adjacent the fluid inlet port for : *. delivering the fluid into the heat exchanger through the fluid inlet port. S...

S

Preferably, the temperature sensing means comprises a temperature sensor.

Ideally, the temperature sensing means comprises a thermistor.

In one embodiment of the invention the one of the heat source and the heat sink comprises a heat source.

In another embodiment of the invention the heat source comprises a boiler.

Preferably, the boiler comprises a burner, and the activating signal produced by the monitoring means is applied to the burner for activation thereof.

In one embodiment of the invention the reservoir is adapted for storing the heat exchange water at a temperature in the range of 90°C to 99°C. Preferably, the reservoir is adapted for storing the heat exchange water at a temperature in the to range of 90°C to 95°C.

In another embodiment of the invention the boiler is adapted for heating the heat exchange water in the reservoir to a temperature in the range of 90°C to 99°C.

Preferably, the boiler is adapted for heating the heat exchange water in the reservoir is to a temperature in the range of 90°C to 95°C.

In another embodiment of the invention the heat exchanger is adapted for transferring heat from the heat exchange medium to the fluid.

In one embodiment of the invention the monitoring means is responsive to the change in temperature of the heat exchanger being indicative of a change in the ***.

temperature of the fluid adjacent the fluid inlet port to the heat exchanger being * indicative of the flow of the fluid through the heat exchanger for producing the activating signal. * . * *** * * 25 a..

* Preferably, the monitoring means is responsive to the signal from the temperature : .. sensing means being indicative of a change in the temperature of the heat exchanger in the range of 0.1°C to 2°C for producing the activating signal.

Advantageously, the monitoring means is responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger in the range of 0.2°C to 1°C for producing the activating signal.

Ideally, the monitoring means is responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger of the order of 0.5°C for producing the activating signal.

In one embodiment of the invention the heat exchanger is adapted for accommodating a fluid therethrough comprising water.

The invention will be more clearly understood from the following description of a preferred embodiment thereof, which is given by way of example only, with reference to Fig. 1 in the accompanying drawing, which illustrates a combination according to the invention of a heat source and a heat exchanger for heating domestic hot water.

Referring to the drawing, there is illustrated a combination according to the invention, indicated by the reference numeral 1, of one of a heat source and a heat sink, which in this embodiment of the invention comprises a boiler 2 and a high temperature is reservoir 3 for holding a high temperature heat exchange medium, a heat exchanger 4, and apparatus also according to the invention, indicated generally by the reference numeral 5, for detecting flow of a fluid through the heat exchanger 4. The apparatus 5 is described in detail below. The fluid which flows through the heat exchanger 4 and is heated in the heat exchanger 4 is water for use as domestic hot water. In this embodiment of the invention the high temperature heat exchange medium is high temperature heat exchange water, which is heated directly by the IS..

boiler 2. A flow pipe 8 supplies the heat exchange water from the reservoir 3 to the *IS lid * heat exchanger 4, and a return pipe 9 returns the heat exchange water from the heat exchanger 4 to the boiler 2. A coupling pipe 10 supplies the high temperature heat exchange water from the boiler 2 to the reservoir 3. S..

: es, The boiler 2, the reservoir 3 and the heat exchanger 4, together with the flow and C...

* return pipes 8 and 9 and the coupling pipe 10 form a closed circuit. A circulating pump 12 located in the coupling pipe 10 circulates the heat exchange water through the boiler 2, the reservoir 3 and the heat exchanger 4. Heat is transferred in the heat exchanger 4 from the heat exchange water from the reservoir 3 to the water to be heated flowing through the heat exchanger 4 to produce the domestic hot water.

The water to be heated is supplied to the heat exchanger 4 from a header tank (not shown), which in turn is supplied by a mains water supply, which typically is provided by a local authority mains water service provider. The domestic water from the header tank (not shown) is delivered to the heat exchanger 4 through an inlet pipe 14. Heated domestic water from the heat exchanger 4 is supplied through an outlet pipe 15 for washing and the like. The domestic water from the inlet pipe 14 is delivered to the heat exchanger 4 through a water inlet port 16, and is delivered from the heat exchanger 4 through a water outlet port 17 to the outlet port pipe 15.

The boiler 2 may be oil fired or gas fired by an oil fired or gas fired burner 19, and is adapted for heating the heat exchange water to a temperature so that the temperature of the heat exchange water in the reservoir 3 is maintained at a relatively high temperature just below boiling point. In this embodiment of the invention the heat exchange water in the reservoir 3 is maintained at a temperature in the range of 90°C to 95°C. The burner 19 is operated to heat the heat exchange water in the boiler 2 to a temperature also in the range of 90°C to 95°C. Due to the fact that the heat exchange water in the reservoir 3 is maintained at the temperature in the range of 90°C to 95°C, the volume of the reservoir 3 may be relatively small, and typically, is of the order of 12 litres. Thermostats (not shown) in the boiler 2 and in the reservoir 3 control the operation of the burner 19 and the circulating pump 12 for maintaining the heat exchange water in the boiler 2 and in the reservoir 3 at the temperature in the range of 90°C to 95°C, so that when the temperature of the heat * * exchange water drops below the temperature between 90°C and 95°C at which the * .. heat exchange water should be maintained within the boiler 2 and the reservoir 3, * e. w.. *

the burner 19 and the circulating pump 12 are operated in order to maintain the heat a..

* exchange water at the temperature within the range of 90°C to 95°C. * 4.

* L. * * The apparatus 5 for detecting flow of the domestic water through the heat exchanger *,.

* 4 comprises a temperature sensing means, which in this embodiment of the invention is provided by a thermistor 20 mounted on the inlet pipe 14 adjacent the water inlet port 16 to the heat exchanger 4 for monitoring the temperature of the heat exchanger 4 adjacent the water inlet port 16. The monitored temperature is thus indicative of the temperature of the domestic water adjacent the water inlet port 16.

The thermistor 20 produces an output signal on the line 21 which is indicative of the monitored temperature. A monitoring means, which in this embodiment of the invention comprises a microcontroller 22 in a control circuit 24 reads the output signal from the thermistor 20. The microcontroller 22 is programmed so that on detecting a change in the monitored temperature, in this case a drop in the monitored temperature which would be indicative of the flow of domestic water through the heat exchanger 4, the microcontroller 22 outputs respective activating signals on a line 25 to the burner 19 of the boiler 2 and on a line 27 to the pump 12 for activating the burner 19 and the pump 12 in order to maintain the heat exchange water in the reservoir 3 at the temperature in the range of 90°C to 95°C, or if the rate of draw off of domestic hot water from the heat exchanger 4 is relatively high, the burner 19 and the pump 12 are operated in order to minimise the rate of fall of the temperature of the heat exchange water in the reservoir 3.

During periods when no domestic water is being drawn through the heat exchanger 4 or when the flow of domestic water through the heat exchanger 4 is relatively low, such as would result from, for example, a dripping tap, the temperature of the domestic water in the water inlet port 16, and in turn in the water inlet pipe 14 adjacent the water inlet port 16 remains substantially constant and of a temperature substantially similar to the temperature of the water in the heat exchanger 4. Thus, under these conditions the temperature of the water in the boiler 2 and in the reservoir 3 is controlled by the thermostats (not shown) in the boiler 2 and in the * ** reservoir 3. However, on domestic water being drawn through the heat exchanger 4, fresh domestic water is drawn through the water inlet port 16 which is significantly * colder than the water in the heat exchanger 4. This drop in the temperature of the : ** domestic water results in a temperature drop in the monitored temperature which is thus indicative of the flow of domestic water through the heat exchanger 4. In this p. embodiment of the invention the microcontroller 22 is programmed to output the activating signals on the lines 25 and 27 to activate the burner 19 and the circulating pump 12, respectively, on the temperature drop of the monitored temperature being of the order of 0.5°C. Once activated by the activating signals, the burner 19 and the circulating pump 12 operate in response to the thermostats (not shown) in the boiler 2 and in the reservoir 3.

In use the microcontroller 22 monitors the output signal from the thermistor 20 on the line 21. On the microcontroller 22 determining that the output signal from the thermistor 20 is indicative of a drop in the monitored temperature of the order of 0.5°C, the microcontroller 22 outputs the activating signals on the lines 25 and 27 for activating the burner 19 and the circulating pump 12 for either maintaining the temperature of the heat exchanger water in the reservoir 3 and in the heat to exchanger 4 at the temperature within the range of 90°C to 95°C, or if the flow of domestic water through the heat exchanger 4 is excessively high, for minimising the rate of fall in the temperature of the heat exchange water in the reservoir 3, and in turn in the reservoir 4. Once activated the burner 19 and the circulating pump 12 operate in response to the thermostats (not shown) in the boiler 2 and in the reservoir 3.

The advantages of the invention are many. By virtue of the fact that the flow of domestic water through the heat exchanger 4 is detected by a thermistor 20, a particularly low cost, substantially maintenance free and substantially failure free apparatus for detecting flow of water through the heat exchanger 4 is provided. The thermistor 20, having no moving parts, is substantially maintenance free, and is *S..

substantially failure proof. Additionally, the thermistor 20 is a relatively low cost component, and is of considerably lower cost than mechanical flow detectors used in * * such combination boiler and heat exchanger systems known heretofore. * ** * * * *** S

** A further advantage of the invention is that it has been found that the response time between the commencement of domestic water being drawn through the heat exchanger 4 and the outputting of the activating signals on the lines 25 and 27 for activating the burner 19 and the circulating pump 12 is between twenty seconds and thirty seconds. Thus, if domestic water is being drawn through the heat exchanger for a relatively short time period of less than twenty to thirty seconds, the boiler is not activated. This has a particular advantage in avoiding a build-up of carbon in the boiler and fuel wastage, which would otherwise arise if the burner 19 were deactivated during the start-up sequence, which, in general, takes approximately between twenty seconds and thirty seconds. If the burner once activated is not permitted to run through the entire start-up sequence and commence normal operation, carbon deposits tend to build up in the boiler, thus necessitating frequent servicing thereof, as well as resulting in waste of fuel.

Accordingly, the response time of approximately twenty seconds to thirty seconds of the apparatus according to the invention between commencement of flow of domestic water through the heat exchanger 4 and the outputting of the activating signals on the lines 25 and 27 has the advantage that the burner is not activated in response to relatively small volumes of domestic water being drawn through the heat exchanger 4 for short periods of less than between twenty seconds and thirty seconds. Indeed, this has been a problem of known apparatus which rely on a is mechanical paddle flow switch for detecting water being drawn through a heat exchanger, since immediately upon movement of the mechanical paddle flow switch the burner of the boiler is activated.

Additionally, the apparatus according to the invention does not activate the burner of the boiler in response to low flow rates of domestic water through the heat exchanger, which would typically be caused by a dripping tap, since the temperature * of the heat exchanger would operate at a relatively steady state in response to such low domestic water flow rates. * * * S.

:.: *. 25 While the temperature sensing means has been described as being a thermistor, any other suitable temperature sensing means may be provided, such as a thermocouple, or any other suitable temperature sensor. S. * . S

While the thermistor has been described as being attached to the inlet pipe 14 adjacent the water inlet port 16 of the heat exchanger 4, the thermistor may be located on the heat exchanger in any suitable location. Indeed, in certain cases, the thermistor may be mounted on the inlet port 16 of the heat exchanger. It is also envisaged that the temperature sensing means, whether it is provided by a temperature sensor or a thermistor or any other suitable temperature sensing means, may be provided on the outlet from the heat exchanger through which heat exchange medium is returned from the heat exchanger to the boiler.

While the combination of the heat exchanger and the one of a heat source and a heat sink has been described as comprising a heat source in the form of a boiler, any other suitable heat source may be provided. It is also envisaged that the combination may be provided with a heat sink instead of a heat source, and in which case the heat exchanger would be adapted for cooling or chilling instead of for heating. When the heat source is replaced with a heat sink, the microcontroller would be programmed to output the activating signals on detection of a rise in the temperature of the fluid adjacent the inlet port to the heat exchanger.

It will also be appreciated that in some embodiments of the invention the reservoir for the heat exchange medium may be omitted, and where a storage means is required for storing the heat exchange medium, any other suitable storing means may be provided. * S S...

S.S... * * * S. * . S 555 5

S S..

S * .0 * S * *55

S *55 a

Claims

Claims 1 A method for detecting flow of a fluid through a heat exchanger, the method comprising monitoring a temperature indicative of the temperature of the heat exchanger, and detecting a change in the temperature thereof indicative of flow of the fluid through the heat exchanger.
2. A method as claimed in Claim 1 in which the temperature of the heat exchanger is monitored adjacent a fluid inlet port to the heat exchanger for accommodating the fluid into the heat exchanger.
3. A method as claimed in Claim 2 in which the temperature of the heat exchanger adjacent the fluid inlet port is monitored by monitoring the temperature of an inlet pipe adjacent the fluid inlet port delivering the fluid to the heat exchanger through the fluid inlet port.
4. A method as claimed in any preceding claim in which the temperature of the heat exchanger is monitored by a temperature sensing means.
5. A method as claimed in Claim 4 in which the temperature sensing means comprises a temperature sensor.

*.
6. A method as claimed in Claim 4 or 5 in which the temperature sensing means *S** comprises a thermistor. * **

:.: * 25
7. A method as claimed in any preceding claim in which an activating signal is ** produced in response to a change in the temperature of the heat exchanger being indicative of flow of the fluid therethrough. * ** ** *

**
8. A method as claimed in Claim 7 in which the activating signal is produced in response to the change in the temperature of the heat exchanger being indicative of a change in the temperature of the fluid adjacent the fluid inlet port to the heat exchanger.
9. A method as claimed in Claim 7 or 8 in which the activating signal is produced in response to the change in temperature of the heat exchanger being in the range of 0.1°C to 2°C.
10. A method as claimed in any of Claims 7 to 9 in which the activating signal is produced in response to the change in temperature of the heat exchanger being in the range of 0.2°C to 1°C.
11. A method as claimed in any of Claims 7 to 10 in which the activating signal is produced in response to the change in temperature of the heat exchanger being in the order of 0.5°C.
12. A method as claimed in any preceding claim in which the fluid is water.
13. A method as claimed in any preceding claim in which the fluid is domestic water.
14. A method as claimed in any preceding claim in which the heat exchange medium is heat exchange water. **,*

******
15. A method as claimed in any preceding claim in which the heat exchanger is adapted for transferring heat from the heat exchange medium into the fluid for heating thereof. * * * * *** *
16. A method for detecting flow of a fluid through a heat exchanger, the method being substantially as described herein with reference to and as illustrated in the * *.accompanying drawings. * ***S
17. Apparatus for detecting flow of fluid through a heat exchanger, the apparatus comprising a temperature sensing means for detecting a temperature indicative of the temperature of the heat exchanger and for producing a signal indicative of the temperature of the heat exchanger, and a monitoring means for monitoring the signal from the temperature sensing means, the monitoring means being responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger indicative of flow of fluid through the heat exchanger for producing an activating signal.
18. Apparatus as claimed in Claim 17 in which the temperature sensing means is adapted for mounting adjacent a fluid inlet port of the heat exchanger through which the fluid is delivered into the heat exchanger.
19. Apparatus as claimed in Claim 17 or 18 in which the temperature sensing means is adapted for mounting on an inlet pipe adjacent the fluid inlet port for delivering the fluid into the heat exchanger through the fluid inlet port.
20. Apparatus as claimed in any of Claims 17 to 19 in which the temperature sensing means comprises a temperature sensor.
21. Apparatus as claimed in any of Claims 17 to 20 in which the temperature sensing means comprises a thermistor.
22. Apparatus as claimed in any of Claims 17 to 21 in which the monitoring means comprises a microcontroller.

* ** .*& *
23. Apparatus as claimed in any of Claims 17 to 22 in which the activating signal $ * S is adapted for applying to one of a heat source and a heat sink for activating the one of the heat source and the heat sink to one of heat and cool the heat exchange * ,* medium for supplying to the heat exchanger. * S
24. Apparatus as claimed in Claim 23 in which the activating signal is adapted for applying to a circulating means for circulating the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.
25. Apparatus as claimed in Claim 24 in which a reservoir is provided for storing the heat exchange medium, and the circulating means circulates the heat exchange medium sequentially through the one of the heat source and the heat sink, the reservoir and the heat exchanger.
26. Apparatus as claimed in any of Claims 23 to 25 in which the one of the heat source and the heat sink is a boiler.
27. Apparatus as claimed in Claim 26 in which the boiler comprises a burner, and the activating signal is adapted for applying to the burner for activating thereof.
28. Apparatus for detecting flow of a fluid through a heat exchanger, the apparatus being substantially as described herein with reference to and as illustrated in the accompanying drawings.
29. In combination a heat exchanger and one of a heat source and a heat sink communicating with the heat exchanger for circulation of a heat exchange medium between the heat exchanger and the one of the heat source and the heat sink, and apparatus as claimed in any of Claims 17 to 28 for detecting flow of fluid through the heat exchanger.
30. In combination a heat exchanger and one of a heat source and a heat sink communicating with the heat exchanger for circulation of heat exchange medium between the heat exchanger and the one of the heat source and the heat sink, and apparatus for monitoring the temperature of the heat exchanger for detecting flow of a fluid through the heat exchanger, the apparatus comprising a temperature sensing * means for detecting a temperature indicative of the temperature of the heat exchanger and for producing a signal indicative of the temperature of the heat exchanger, and a monitoring means for monitoring the signal from the temperature sensing means, the monitoring means being responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger indicative of fluid flow through the heat exchanger for producing an activating signal and applying the activating signal to the one of the heat source and the heat sink for activating thereof,
31. The combination as claimed in Claim 30 in which a circulating means is s coupled to the heat exchanger and the one of the heat source and the heat sink for circulating the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.
32. The combination as claimed in Claim 31 in which the activating signal produced by the monitoring means is applied to the circulating means for activating thereof to circulate the heat exchange medium between the heat exchanger and the one of the heat source and the heat sink.
33. The combination as claimed in Claim 31 or 32 in which a storing means is provided for the heat exchange medium, the storing medium being coupled to the heat exchanger and the one of the heat source and the heat sink, so that the heat exchange medium is circulated sequentially through the one of the heat source and the heat sink, the storing means and the heat exchanger.
34. The combination as claimed in Claim 33 in which the circulating means is *.I.adapted for circulating the heat exchange medium sequentially through the one of the heat source and the heat sink, the storing means and the heat exchanger.
35. The combination as claimed in Claim 33 or 34 in which the heat exchange medium is heat exchange water, and the storing means comprises a reservoir for : storing the heat exchange water.
36. The combination as claimed in Claim 35 in which the capacity of the reservoir lies in the range of 5 litres to 20 litres.
37. The combination as claimed in Claim 35 or 36 in which the capacity of the reservoir lies in the range of 10 litres to 15 litres.
38. The combination as claimed in any of Claims 35 to 37 in which the capacity of the reservoir is in the order of 12 litres.
39. The combination as claimed in any of Claims 30 to 38 in which the temperature sensing means is located adjacent a fluid inlet port to the heat exchanger through which the fluid is accommodated into the heat exchanger.
40. The combination as claimed in any of Claims 30 to 39 in which the io temperature sensing means is adapted for mounting on an inlet pipe adjacent the fluid inlet port for delivering the fluid into the heat exchanger through the fluid inlet port.
41. The combination as claimed in any of Claims 30 to 40 in which the temperature sensing means comprises a temperature sensor.
42. The combination as claimed in any of Claims 30 to 41 in which the temperature sensing means comprises a thermistor.
43. The combination as claimed in any of Claims 30 to 42 in which the one of the heat source and the heat sink comprises a heat source.*....S * * : *
44. The combination as claimed in Claim 43 in which the heat source comprises * a boiler. * *.SS* **
45. The combination as claimed in Claim 44 in which the boiler comprises a burner, and the activating signal produced by the monitoring means is applied to the burner for activation thereof.
46. The combination as claimed in Claim 44 or 45 in which the reservoir is adapted for storing the heat exchange water at a temperature in the range of 90°C to 99°C.
47. The combination as claimed in any of Claims 44 to 46 in which the reservoir is adapted for storing the heat exchange water at a temperature in the range of 90°C to 95°C.S48. The combination as claimed in any of Claims 44 to 47 in which the boiler is adapted for heating the heat exchange water in the reservoir to a temperature in the range of 90°C to 99°C.io 49. The combination as claimed in any of Claims 44 to 48 in which the boiler is adapted for heating the heat exchange water in the reservoir to a temperature in the range of 90°C to 95°C.50. The combination as claimed in any of Claims 44 to 49 in which the heat i 5 exchanger is adapted for transferring heat from the heat exchange medium to the fluid.51. The combination as claimed in any of Claims 30 to 50 in which the monitoring means is responsive to the change in temperature of the heat exchanger being indicative of a change in the temperature of the fluid adjacent the fluid inlet port to the heat exchanger being indicative of the flow of the fluid through the heat exchanger for producing the activating signal. * **52. The combination as claimed in any of Claims 30 to 51 in which the monitoring I..* 25 means is responsive to the signal from the temperature sensing means being * ** indicative of a change in the temperature of the heat exchanger in the range of 0.1°C to 2°C for producing the activating signal. S..S53. The combination as claimed in any of Claims 30 to 52 in which the monitoring means is responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger in the range of 0.2°C to 1°C for producing the activating signal.54. The combination as claimed in any of Claims 30 to 53 in which the monitoring means is responsive to the signal from the temperature sensing means being indicative of a change in the temperature of the heat exchanger of the order of 0.5°C for producing the activating signal.55. The combination as claimed in any of Claims 30 to 54k in which the heat exchanger is adapted for accommodating a fluid therethrough comprising water.56. The combination of a heat exchanger and one of a heat source and a heat sink and apparatus for detecting flow of a fluid through the heat exchanger, the combination being substantially as described herein with reference to and as illustrated in the accompanying drawings. * SSS..... * S * *S * S SS SSS * S. 5 *ISSS *ISS