Leak Detection Method and Apparatus

Abstract

A method for estimating a position or height of a leak within at least a part of a water system, the method comprising the use of two pressure sensors and a pump, wherein one of the two pressure sensors is located towards a top of the part of the water system being tested and the other pressure sensor is located towards a bottom of the part of the water system being tested, the pump being for enabling maintenance of a volume of air above the water level within the water system at a pressure greater than atmospheric to make the water in the water system pressurised, the method comprising closing all known water usage taps within the part of the water system to be tested, isolating the part of the water system (50) from its replacement water source, checking the pressures on the sensors and elevating the pressure of the volume of air if needed to pressurise the water system and determining the difference between the pressures sensed by two pressure sensors to determine a head of the water within the system, the head representing the height of the water above the lower of the two sensors, intermittently venting water out of the water system and measuring the pressures sensed by the two pressure sensors once the vents are closed to allow a subsequent head to be calculated and re-ascertaining the differences between the pressures to calculate the new head, wherein if the detected pressures start to drop faster than normal whilst the system is isolated after one such intermittent venting of water, the location of a leak has been identified as at, or just above, the top of the water level, the height thereof being represented by the head just calculated.

Claims

1-35. (canceled)

36. A method for estimating a position or height of a leak within at least a part of a water system, the method comprising the use of two pressure sensors and a pump, wherein one of the two pressure sensors is located towards a top of the part of the water system being tested and the other pressure sensor is located towards a bottom of the part of the water system being tested, the pump being for enabling maintenance of a volume of air above the water level within the water system at a pressure greater than atmospheric to make the water in the water system pressurised, the method comprising: closing all known water usage taps within the part of the water system to be tested; isolating the part of the water system (50) from its replacement water source; checking the pressures on the sensors and elevating the pressure of the volume of air if needed to pressurise the water system; and determining the difference between the pressures sensed by two pressure sensors to determine a head of the water within the system, the head representing the height of the water above the lower of the two sensors; intermittently venting water out of the water system and measuring the pressures sensed by the two pressure sensors once the vents are closed to allow a subsequent head to be calculated; and re-ascertaining the differences between the pressures to calculate the new head; wherein if the detected pressures start to drop faster than normal whilst the system is isolated after one such intermittent venting of water, the location of a leak has been identified as at, or just above, the top of the water level, the height thereof being represented by the head just calculated.

37. The method of claim 36, further comprising a balloon, connected to the volume of air.

38. The method of claim 36, wherein the water system is a non-pressurised water system fed by a header tank.

39. The method of claim 36, wherein the calculated values of the head are monitored or recorded.

40. The method of claim 39, wherein if the head remains constant for a sequence of water releases, the method will establish that the water system at that head comprises horizontal pipework.

41. The method of claim 39, wherein if the head drops during a sequence of water releases, then the method establishes that through that range of heads the water system comprises vertical pipework.

42. The method of claim 40, wherein if the head drops during a sequence of water releases, then the method instead establishes that through that range of heads the water system comprises vertical pipework, the method thus being arranged to schematically map a building's plumbing system.

43. The method of claim 36, wherein the vented water is vented as units of water, the units being approximately fixed volumes of water determined by timed duration of release, the timed duration of release remaining constant for each intermittent release of water, whereby approximated water volumes for each release are known for a given pressure and vent size.

44. The method of claim 43, wherein with the information regarding the volume of water vented, the method then also approximates the cross sectional area of any detected vertical pipework at a given head by dividing the approximated or measured volume of water vented in a particular sequence by the change of head height measured.

45. The method of claim 43, wherein with the information regarding the volume of water vented, the method then also approximates the length of horizontal pipes located in any detected horizontal stretch by dividing the approximated or measured volume of water vented by a standardised cross-sectional area for the type of pipes being tested.

46. The method of claim 36, wherein the method monitors the head for a period of time between each venting of water, in particular when detecting a drop in head after a period of static head, and if after the initial drop in head, the head is still slowly dropping during that period of time, then the method determines that the water level is above the leak, so the testing can continue to a next release of water, whereas if the head instead stops falling, the leak can be concluded to be in the horizontal section identified by the static head.

47. The method of claim 36, wherein if the measured pressure at the top drops below a set minimum, the pump is used to pump more air in at the top as the pressure in the section being tested needs to exceed the static head pressure.

48. The method of claim 36, wherein if the measured pressure at the bottom rises above a set maximum, the pump or a pressure release valve is opened to allow air out of the water system.

49. An automated method for mapping at least a part of a water system, the method comprising the use of two pressure sensors and a pump, wherein an upper of the two pressure sensors is located towards a top of the part of the water system being tested and the a lower of the two pressure sensors is located towards a bottom of the part of the water system being tested, the pump being for enabling maintenance of a volume of air above the water level within the, water system at a pressure greater than atmospheric to make the water in the water system pressurised, the method comprising: closing all known water usage taps within the part of the water system to be tested; isolating the part of the water system (50) from its replacement water source; checking the pressures on the sensors and elevating the pressure of the volume of air if needed to pressurise the water system; and determining the difference between the pressures sensed by two pressure sensors to determine a head of the water within the system, the head representing the height of the water above the lower sensor; intermittently venting water out of the water system and measuring the pressures sensed by the two pressure sensors once the vents are closed to allow a subsequent head to be calculated; and re-ascertaining the differences between the pressures to calculate the new head; wherein if the head remains constant for a sequence of water releases, the method will establish that the water system at that head comprises horizontal pipework, and if the head drops during a sequence of water releases, then the method establishes that through that range of heads the water system comprises vertical pipework.

50. The method of claim 49, wherein the vented water is vented as units of water, wherein the units are fixed or measured volumes of water.

51. The method of claim 49, wherein the vented water is vented as units of water, wherein the unit is an approximated volume, determined by a timed duration of release.

52. The method of claim 50, wherein with the information regarding the volume of waterapproximated or measured, the method then also approximates the cross sectional area of any detected vertical pipework at a given head by dividing the approximated or measured volume of water vented in that particular sequence by the change of head height measured.

53. The method of claim 50, wherein with the information regarding the volume of waterapproximated or measured, the method then approximates the length of any detected horizontal pipes located in a horizontal stretch by dividing the approximated or measured volume of water vented, in that particular sequence by the expected cross-sectional area of the pipework based upon standardised cross sectional area values for the pipes being tested.

54. The method of claim 49, wherein if the measured pressure at the top drops below a set minimum, the pump is used to pump more air in at the top as the pressure in the section being tested needs to exceed the static head pressure.

55. The method of claim 49, wherein, if the measured pressure at the bottom rises above a set maximum, the pump or a pressure release valve is opened to allow air out of the water system.

Description

[0201] These and other features of the present invention will now be described in greater detail, purely by way of example, with reference to the accompanying drawings in which:

[0202] FIG. 1 shows an example of a simple unvented or pressurised water system for use in a building;

[0203] FIG. 2 shows an example of a simple vented water system for use in a building;

[0204] FIG. 3 shows a pressure versus time graph illustrating the drop in pressure in a water system over time, and a step drop due to a controlled release of a small volume of water;

[0205] FIG. 4 shows an extrapolated best fit curve for the pressure drop over time;

[0206] FIG. 5 shows a manometer being used to detect a leak in a vented water system;

[0207] FIG. 6 shows a pump and second pressure meter for attachment at an upper part of a building when undertaking a method in accordance with an aspect of the present invention

[0208] FIG. 7 shows a modified version of the assembly in FIG. 6, fitted with a balloon for better security when used on a vented water system;

[0209] FIG. 8 shows a pressure sensor mounted at a washing machine attachment point, for example at a lower position of the building than the arrangement of FIGS. 6 and 7;

[0210] FIG. 9 illustrates how the pressure within the water system dictates the flow rate of water from the system when opening a vent in the piping, such as a tap;

[0211] FIG. 10 shows a basic automated arrangement for implementing aspects of the present invention;

[0212] FIG. 11 shows a more integrated version of the automated arrangement, with a transmitter for communicating with a communications device, or a second pressure sensor, or both;

[0213] FIG. 12 shows the system of FIG. 11, with a second sensor and pump in accordance with FIG. 6 in a three storey water system;

[0214] FIG. 13 illustrates areas below the pressure time plots that can be used in calculations as described above; and

[0215] FIG. 14 illustrates line angles or line drops that can alternatively be used in calculations as described above.

[0216] Referring first of all to FIG. 1 there is disclosed is a vented water system 10 supplied with water from a mains pressure by a mains water supply 12. The mains water supply 12 can be controlled on and off relative to the system 10 by a stop cock 14. The mains supply 12, with the stop cock 14 open, can supply water to one or more cold tap 16, such as one in a kitchen, plus also to a header tank 16usually located in a loft or attic of the building. Its height relative to any tap fed by the system, such as hot water taps 26, i.e. those other than any mains fed taps 16, define the pressure of the system at that tap, i.e. its head.

[0217] The header tank 18 supplies stored water via a pipe to a hot water cylinder 22, usually at or near the bottom of that cylinder 22. That transferred water is then heated by a boiler 20often an immersion heater, or boiler coil for indirect heating. The hot water can then be taken from the cylinder 22, usually from upper parts thereof as shown. Here it is shown to branch off an overflow pipe 28 for the cylinder 22, as is also commonly done.

[0218] The hot water pipe leads to hot water taps 26 elsewhere within the building.

[0219] Referring next to FIG. 2 there is disclosed instead a pressurised or unvented water system 50. Such systems can also be referred to as a sealed water system. This alternative form of water system 50 is held at mains pressure effectively throughout the system 50, rather than relying on the head of a header tank 18 as the feed pressure for the hot taps 26.

[0220] The pressure in this system 50 is maintained at the mains pressure by its connection to a mains water supply 12. It can be isolated from the mains water supply 12 by a stop cock 14, as could the vented system. It can also have cold taps between that stop cock 14 and its hot water cylinder 22. Furthermore the hot water cylinder 22 is still heated by a boiler 20perhaps via a coil in the tank, or with an emersion heater. However, in place of the overflow pipe 28, there is instead an expansion vessel or EV 52 which contains a bladder 54 surrounded by air, and containing the overflow (an over-feed or buffer) of water, which air is compressed to a greater or lesser extent as the pressure in the system increases or decreases due to either fluctuations in the main pressure, or due to the heating of the water in the cylinder, or the release of water through the hot or cold taps 16, 26. A steadied water flow, and an avoidance of explosive or excessive pressures within the cylinder 22, can thus be achieved (the EV52 can have a pressure release valve for releasing excessive pressures).

[0221] With either system 10, 50, water may instead be heated on demand by a combi-boiler, avoiding the need for a hot water cylinder, although combi-boilers are more usually used in unvented systems.

[0222] Determining Leak Rate on a Pressurised System

[0223] The first aspect of the present invention provides a method for each of the above systems that allows a detection or investigation/testing of a leak. In addition to detecting or testing a leak, however, the present invention can also attempt to determine or approximate a leak rate.

[0224] The inventors have realised that a rate of depressurisation alone will not give us an actual leak rate (in terms of how much water is leaking over a given time period). After all, if a lot of air is present, a relatively large leak will only lead to a small depressurisation. Conversely, if only a small amount of air is present, even a small leak can lead to a large depressurisation. The explanation behind this is as follows:

[0225] Boyle's law states that: [0226] Pressure is proportionate to 1/Volume

[0227] The relationship is only approximate as it depends upon the amount of heat that is created and removed from the system, but is sufficiently accurate for the purposes of this analysis.

[0228] From this starting point, imagine a leak causes a certain volume of water V.sub.L to leave a system over a time t. Since water is essentially incompressible at mains water pressure, the departing water will stretch any air pockets in the system, causing the air to increase in volume equal to the displaced V.sub.L.

[0229] The inventors therefore considered how to estimate the leak rate, based on observations of pressures in a water system over time:

[0230] Where the initial pressure is P.sub.0 and the second pressure, at time t, is P.sub.1, we can start with the following equations:

Initial pressure=P.sub.0=k/V.sub.air

[0231] Pressure after leak has released a volume of water (i.e. after time t)=P.sub.1=k/(V.sub.air+V.sub.L)

[0232] Hence: k=V.sub.air*P.sub.0=(V.sub.air V.sub.L)*P.sub.1

[0233] Thus P.sub.1=P.sub.0*V.sub.air/(V.sub.air+V.sub.L)

[0234] On the one hand, if V.sub.L is small compared to V.sub.air, P.sub.1P.sub.0

[0235] On the other hand, if V.sub.L is more substantial, P.sub.1 will be notably smaller. For example:

[0236] if V.sub.L=V.sub.air, then P.sub.1=P.sub.0*1/2

[0237] Unfortunately there are two unknowns; V.sub.L and V.sub.air. This means that the volume of leaked water V.sub.L cannot be determined unless the volume of air in the system is known, and that volume will vary substantially depending upon the system type (vented or unvented, and the state of the expansion vessel). Furthermore, it cannot directly be measured.

[0238] Hence a second equation is needed to solve the problem.

[0239] The first aspect of the present invention provides the means for providing the solution: by releasing a fixed volume of water V.sub.R from the system (e.g. by filling a beaker from a tap), and recording the new pressure P.sub.2 after this known volume of water has been released from the system, we can arrive at a useful equation:

P.sub.2=k(V.sub.air+V.sub.L+V.sub.R)

[0240] Thus k=(V.sub.air+V.sub.L+V.sub.R)*P.sub.2,

[0241] We also know that k=(V.sub.air+V.sub.L)*P.sub.1 and k=V.sub.air*P.sub.0

[0242] and consequently that V.sub.air*P.sub.0=(V.sub.air+V.sub.L)*P.sub.1

[0243] So: V.sub.air*P.sub.0)/P.sub.1=V.sub.air+V.sub.L

[0244] (P.sub.0/P.sub.11)*V.sub.air=V.sub.L

[0245] V.sub.air=V.sub.L/(P.sub.0/P.sub.11)

[0246] And V.sub.air*P.sub.0=(V.sub.air+V.sub.L+V.sub.R)*P.sub.2

[0247] This gives us:

V.sub.L*P.sub.0/(P.sub.0/P.sub.11)=(V.sub.L/(P.sub.0/P.sub.11)+V.sub.L+V.sub.R)*P.sub.2

[0248] Further, V.sub.L*P.sub.0/(P.sub.0/P.sub.11)=V.sub.L*P.sub.2(1+1/(P.sub.0/P.sub.11))+V.sub.R*P.sub.2

[0249] V.sub.L*(P.sub.0/(P.sub.0/P.sub.11)P.sub.2(1+1/(P.sub.0/P.sub.11)))=V.sub.R*P.sub.2

[0250] V.sub.L*(P.sub.0(P.sub.2*P.sub.0)/P.sub.1)/(P.sub.0/P.sub.11)=V.sub.R*P.sub.2

[0251] V.sub.L*(P.sub.0*P.sub.1P.sub.2*P.sub.0)/P.sub.1*P.sub.1/(P.sub.0P.sub.1)=V.sub.R*P.sub.2

[0252] V.sub.L*P.sub.0(P.sub.1P.sub.2)/(P.sub.0P.sub.1)=V.sub.R*P.sub.2

[0253] We thus finally arrive at the volume leaked out V.sub.L=V.sub.R*P.sub.2(P.sub.0P.sub.1)/(P.sub.0(P.sub.1P.sub.2))

[0254] Using this formula, and the example of the pressure readings taken from FIG. 3, a reasonably accurate leak rate (V.sub.L/t) can be determined from the initial pressure reading P.sub.0, the pressure reading P.sub.1 just before the release of the controlled volume of water V.sub.R (i.e. after time t) and the pressure reading P.sub.2 just after the controlled volume of water was released, as set out in Table 1:

TABLE-US-00001 TABLE 1 Data reading Workings: V.sub.R 43 ml P.sub.0 1221.2 mBar V.sub.L = V.sub.R * P.sub.2 (P.sub.0 P.sub.1)/(P.sub.0 (P.sub.1 P.sub.2)) P.sub.1 1081.4 mBar V.sub.L = 69.2 ml p.sub.2 1009.47 mBar t = 5 mins. Thus leak/min = 12.2 ml

[0255] An alternative way to achieve a similar result is to fit a curve or a line to the pressure trace before the water release and a separate one after the water release using a method such as least squares or similar. These can be extrapolated across the period of the water release, and the vertical distance between the two curves calculated at the release point. This has the advantage that it can be smoothed over shock waves in the pressure that can occur during or for a while after the release. It can also allow for a delay in the sampling period of the pressure sensor, for example if the sensor samples at 5 second intervals, the point P.sub.2 may not be exactly known as it could be 4 seconds after the actual release, or the release may coincide with taking the sample and a misleadingly low pressure is measured due to a low pressure wave passing the pressure sensor. As such, data points P.sub.0, P.sub.1 and P.sub.2 are calculated, rather than measured, from the best fit curves. An example using such extrapolation is given in FIG. 4.

[0256] To carry out these first aspects of the present invention a useful approach to take follows the following steps: [0257] 1) Ensure all taps etc. within the pressurised section being tested are off so that no intended water-use is occurring. [0258] 2) Attach a pressure sensor to the pressurised part of the water system. [0259] 3) With the system at mains pressure, turn off the stopcock to disconnect from the mains pressure supply. [0260] 4) Commence (or continue) taking pressure readings from the pressure sensor. [0261] 5) Leave the system alone for a period of time, optionally continuing to take pressure readings, this step involving taking at least one additional pressure reading prior to the next step. [0262] 6) Release a small volume of water (V.sub.R) out of the system, usually into a measuring beaker so that the volume taken is measured. [0263] 7) Take at least one further pressure after releasing the volume of water. [0264] 8) Establish from the pressure readings a first pressure value P.sub.0 as a starting pressure at a given time t before the release of the water; [0265] 9) Establish from the pressure readings a second pressure value P.sub.1 representing the pressure just before the water was released; [0266] 10) Establish from the pressure readings a third pressure value P.sub.2 representing a the pressure just after the release of water; [0267] 11) Feed the values of P.sub.0, P.sub.1, P.sub.2 and V.sub.R into the following equation for calculating V.sub.L:

V.sub.L=V.sub.R*P.sub.2(P.sub.0P.sub.1)/(P.sub.0(P.sub.1P.sub.2)) [0268] thus estimating a total volume of water that has leaked out (V.sub.L). [0269] 12) Divide this value V.sub.L by the amount of time in minutes (t) between P0 and P1 to determine the leak rate per minute.

[0270] It is possible also to do the test without the calculations, whereby data is sourced for evaluation.

[0271] It is also possible to take the pressures either side of the release of water, and the release of water, before taking the readings during the time t, and even to reset the pressure between each set of readings. The above, however, describes a preferred embodiment.

[0272] Commonly the additional readings at steps 5 and 7 are taken within 5 seconds, or perhaps within 10 or 20 seconds or even 1 minute of the start and end of the release of water, respectively. Such short time intervals will give accurate results in most instances. Longer intervals may degrade the accuracy, although results may still be adequately accurate as a calculated approximation of the actual leak rate.

[0273] If the leak rate is below a pre-determined minimum, a decision can be taken that the system is not currently leaking at a rate that would lead to concern. If it exceeds such a minimum, however, it is determined that the leak needs further investigation, and subsequently a likely repair.

[0274] Commonly the pressure sensor would be applied at a convenient take-off point, such as a standard washing machine attachment point, or by removing a valve mechanism from inside a tap and replacing it with a suitable fitting for connecting a pressure sensor. Suitable pressure sensors could be electronic pressure sensors and the appropriate fittings are readily available for most standard size taps or washing machine attachment points.

[0275] The above method will generally be preferred to be used on unvented, i.e. pressurised systems. However, it can also be used on a header tank-fed side of a vented system 10, although the header tank would want to be thoroughly isolated, e.g. by closing a valve thereof.

[0276] It is also to be appreciated that the method can be adapted in line with the various variants discussed above in the statements of invention.

[0277] Referring now to a second aspect of the present invention a further approach for testing for leaks is provided.

[0278] In a hot water system, even when heating up a vented system, the pressure does not rise significantly, as vented hot water systems 10 are all equipped with a basic safety feature of the overflow pipe 28 from the hot side of the cylinder 22, that empties any overflow back into the header tank 18. This means that as the hot water cylinder 22 heats up, rather than experiencing a potentially dangerous increase in pressure, excess hot water is simply driven up the overflow pipe 28 and back into the header tank 18, ready to be re-used later.

[0279] Determining whether there is a leak on such a vented hot water system 10 offers a different approach for the invention. It instead involves the second aspect of the present invention, namely attaching a gas manometer 32 to the outlet 30 of the overflow pipe 28, and then putting a bung 34 in the outlet 36 of the header tank 18, both as shown in FIG. 5. As header tanks 18 are usually equipped with easily removable lids, for ease of inspection, inserting a bung 34 is an easy, if cold (due to the tank being deep and filled with cold water) task.

[0280] Step by step instructions for following the second aspect of the present invention can thus be as follows: [0281] 1) Ensure all taps etc. are off so that no intended water-use is occurring. [0282] 2) Bung the outlet of the header tank 18 [0283] 3) Fill a gas manometer 32 with a little water. [0284] 4) Attach one end of the manometer, for example by a length of rubber tube, to the outlet 30 of the overflow pipe 28 [0285] 5) Keep open or open the other end of the manometer such that it is open to the atmosphere. [0286] 6) Observe whether the water in the manometer moves.

[0287] If the water moves there is a leak.

[0288] To continue to a preferred aspect of this second aspect of the inventiondetermining the rate of any leak, the operator can further do the following: [0289] 7) Measure the rate of vertical movement of the water in the manometer, v. The leak rate is v*A where A is the cross sectional area of the manometer tube.

[0290] If the water does not move in the manometer, check that all connections are secure by setting a slow drip on a hot water tap. If the water now starts to move, there is no leak.

[0291] If it still does not move, check connections and try again.

[0292] Having identified the presence of a leak, it is another aspect of the invention (the third) to find it. Prior art approaches tended to take a long time: In theory, water would leave the system at the leak point, causing pressure in the system to fall, until it finally reached equilibrium when the only pressure remaining in the system was that exerted by the head of water sat below the leak. The final location of the leak could thus be determined as this process was happening by extrapolating the pressure vs time curve caused by the leak. In addition to this taking too long, this also had the problem that some leaks only open at high pressure, closing up as the pressure dropped, whereby false locations would be identified. Furthermore, even with a relatively fast leak and a good curve, extrapolating the curve forward may give the location of some flat pipework in the system rather than the leak height itself.

[0293] The third aspect of the invention therefore serves to find the location of the leak more positively, and more quickly.

[0294] According to this third aspect of the present invention the method uses two pressure sensorsone located at the top of the pipework being tested and the other at the bottom, along with a pump to hold the system at a pressure in excess of the head thereof. In essence, the difference between the two sensors indicates the height of water remaining in a system, i.e. the head. This aspect also uses the knowledge that pipes in a building are generally either vertical or horizontal (or a bend) as building regulations, or good plumbing practice, typically require that arrangement.

[0295] With the invention, air is pumped into the system at the top, near the upper pressure sensor, in order to hold the system at a relatively constant high pressurehigher than the pressure arising just from the height of the water therein. In an unvented system this works as stated as the system is designed to operate at such elevated pressures. For a vented system, however, a balloon is optionally added as a precaution as vented systems in normal use will tend to be subjected to lower pressures than an unvented system as they generally only experience the gravity head of the header tank, not mains pressure. Hence it is prudent during testing to limit the pressure as pressures significantly above normal may create additional leaks. If the system is over pressurised, the balloon will burst, depressurising the system immediately.

[0296] Referring to FIG. 6, there is shown an example of a possible upper sensor assembly 60 for use at an upper pressure sensor locationin this case attached to an upstairs hot tap 26. It has a manual pump 40, which can be a bicycle pump with a connector 44 that attaches to a manifold assembly 46 of the upper sensor assembly 60. The manifold also has an attachment 42 that connects into the inside of a tap (once the valve of the tap 26 is removed)usually by having a thread to match a valve-receiving thread inside of the body portion of the tap, and a T branch 66 that connects to a digital pressure gauge 48. Other forms of pump, gauge or manifold arrangement can likewise be used.

[0297] The gauge may be provided with a digital readout as shown, or there can be an analogue one 62as also shown extending elsewhere from the manifold assembly 46. Ideally, however, the gauge is arranged to transmit readings to a processor for allowing automated processing, as explained further below.

[0298] Referring next to FIG. 7, a variant is shown instead for a vented systemit having the aforementioned balloon 64 fitted to it on a second T branch 66.

[0299] Referring next to FIG. 8, a lower pressure sensor is shown, in this instance instead fitted to a standard washing machine attachment point 70. The lower pressure sensor 72 in this embodiment has a pipe with a threaded end for screwing onto that washing machine attachment point 70. The pressure sensor is like the one of FIG. 6 and FIG. 7 in that it is digital with the ability to transmit its reading to a processor. Other pressure gauges are also possible, as would be alternative mounting positions (e.g. another tap, albeit probably a downstairs one.

[0300] The process of locating the leak using this aspect of the present invention is as follows:

[0301] Water is tapped off at the bottom of the system (to speed up the detection process), preferably in fixed volumes. At every stage after a volume of water (fixed or otherwise) is progressively tapped out of the system or section being tested, by opening a tap at the bottom and closing it again, readings are taken from the two pressure sensors (once the tap is closed again). The difference between the two pressure sensors is calculated to give a reading of the head. The following analysis is then performed between the heads detected following each tapped volume: [0302] 1) If the head stays constant relative to the previous reading, i.e. after tapping off a volume, the pipework is flat at the point where the top of the water within the system is locatedlet more water out and retest. [0303] 2) If the head falls, the pipework is assumed to be vertical (or going around a downward facing joint). [0304] a. If this is the first vertical detection after a horizontal part, pause the water release and monitor the head to see if the head is slowly falling. [0305] i. If it is still slowly falling, the water level is above the leak locationlet more water out and retest [0306] ii. If it has stopped falling, reference information for locating the leak has been obtainedthe leak is in the horizontal section, or more likely in a branch or junction of the plumbing that is connected to this horizontal section of pipework (junctions, or water using devices that may be located on a branch of the pipework are more likely to fail than the pipe itself). [0307] b. Air escapes faster from a leak than water and causes a system to depressurise noticeably faster. If the pressures (the readings, not the difference between them) suddenly start falling faster than accountable by the removed water, the leak has been foundit is between current head height and the previous head height [0308] c. If neither a)ii) nor b) apply, let more water out and retest. [0309] 3) If the pressures drop below a set minimum, pump more air in at the top as the pressure in the section being tested needs to exceed the head pressure. [0310] 4) If the pressures rise above a set maximum, let air out at the pump to avoid bursting joints of the system, or causing other leaks to appear.

[0311] This process can thus ascertain the height above the bottom sensor that the leak is located, and the direction in which the pipe is most likely running, whereby its location should be easier to identify.

[0312] A useful side-effect of the above process is a fourth aspect of the inventionit can also be used to map the water system in a building. By measuring how much the head falls when a fixed volume is released from a vertical pipe run, the cross sectional area of the pipework in the system at that height, and thus also most likely the diameter of pipework (or number of pipes) at that height, can be ascertained as different diameters have fixed cross sectional areas, whereby for the height change there will be a predetermined volume (as the pipes are typically horizontal or vertical as mentioned above). Furthermore pipes tend to have standard sizes, thus allowing few permutations to account for any given calculated area. As a result, as water is let out, from the readings taken, the approximate structure of the pipework can reveal itself. For example, the head might constantly fall between 5 metres and 2.8 metres, indicating a vertical section of pipe. It may then stay constant while a volume of water equivalent to 3 metres of horizontal pipe is released, before then starting to drop again. This could thus represent a horizontal pipe run occurring in the ground floor ceiling, perhaps serving different appliances in a first floor bathroom, and thus with one or more vertical run above it, say into the taps or shower.

[0313] According to a fifth aspect of the present invention it is also possible to automate the water release. This aspect can thus be beneficial for each of the first, third and fourth aspects described above.

[0314] Accurate volumetric dispensers exist. However they are expensive. The present inventors desire to provide a system for use by plumbers, and thus making the system less costly is beneficial as plumbers will be more likely to invest in an affordable system.

[0315] The inventors realised that the degree of accuracy provided by accurate volumetric dispensers is not necessary for estimating an approximate leak rate. Instead an approximation is enough.

[0316] They also realised that when dealing with a leak, internal pressure within the system will be constantly dropping as the leak continues.

[0317] When deliberately releasing water from a system, the higher the pressure within the system, for a given vent of a constant size, the faster the water will be released. However, when releasing small volumes of water from a system that contains a fair amount of air, the internal pressure can be approximated as remaining constant during the release of a small volume of water. Thus a relationship between internal pressure and flow rate can be assumed as follows:

Water release ratef(Internal pressure)

[0318] (An empirical map of the relationship between volume dispensed per second through a vent due to the pressure of a test system versus the pressure of the test system is shown in FIG. 9. Although non-linear, it is close to linear.)

[0319] If the orifice that the water is released through is substantially smaller than the diameter of the pipes in the main system, the friction losses in the rest of the pipework become negligible compared to the losses through the orifice, so the flow rate can then also be assumed to be roughly the same at a given pressure, regardless of the pipework in the rest of the system.

[0320] This relationship between pressure and flow can therefore be found experimentally and converted into a table or function that maps flow rate as a function of pressure for a particular vent. Thus, to release a known (small) volume of water, the release mechanism can be triggered simply to open for a set amount of time, calculated from the flow rate versus pressure graph.

[0321] Taking that assumption, and using it in an automated process for testing a water system for leaks, and/or leak rates, the process can constantly and automatically refine or adjust itself: the process, via a computer or processor, can, among other things, time how long the actuator actually was open to determine the volume of water removed, measure whether the internal pressure dropped enough to impact water release rate and thus re-estimate how much water it actually released, and/or to vary the release time period next time, and (when being used with the third or fourth aspects of the present invention) to control the pump to re-pressurise the system if needed. The automated process can thus derive any adjustments needed from the detected pressure in order to more accurately release water in subsequent bursts, and to maintain the test apparatus' functionality.

[0322] Referring next to FIG. 10 a proposed set-up 80 is shown. It comprises a computer 82 to provide processing of pressures detected by, in this instance, the single pressure gauge 72 that branches off a washing machine attachment point 70 that is located downstairs. The gauge is arranged to transmit its pressure readings, so that they can be received by the computer, either directly or through a control board 84 that exchanges data and/or instructions with the computer 82 and an actuator 86. The actuator 86 will thus be able to be controlled to open and close for a predetermined time period for releasing an approximately fixed or known volume of water, and the pressure gauge 72 will be able to feed readings to the computer 82 for processing.

[0323] As shown, the gauge 72 is connected via a secondary T joint 88, and a beaker 90 collects dispensed water. The beaker 90 might instead be a sink or drain. Other connection arrangements are possible for the gauge 72, and the other elements of this set-up 80.

[0324] In a preferred arrangement, the set-up is packaged into a single, low cost integrated unit which can send and receive pressures internally, and likewise control the water flow through its own integrated pipework and actuator. It can also or alternatively transmit and/or receive instructions or readings to or from other devices, such as a second pressure sensor and/or a pump, as per the third aspect of the invention. It can even be arranged to communicate with an external device, e.g. wirelessly, such as a smartphone or computer used by a plumber, for more remote applications, or applications where access with a computer is more restricted. Having an ability to use wireless technologies (or intranet technologies) can also facilitate transmission of data to or from a remote pressure sensor and pump, as per the third aspect of the present invention, to control and receive data from them through a building's Wi-Fi (or intranet). FIG. 11 shows a possible integrated unit 100 for locating at a lower end of a water system 10, 50, or a part thereof. It still has the pressure sensor 72, actuator 86 and a computer/processor/control board 82, 84. It also has a venting pipe 92 and an input pipe 94 for connecting wherever suitable (e.g. the aforementioned washing machine attachment point 70). It also has a transmitter to allow control or interrogation by a smartphone or separate computer, or for receiving data from the second pressure sensor or commands from the smartphone or separate computer (where provided).

[0325] The above processes and equipment can thus all be combined into a single method of detecting and locating leaks as follows: [0326] 1. Checking the pressurised section of the water system using the process of the first aspect of the present inventionthe pressure sensor and timer, or the device of the third, fourth or fifth aspect. [0327] 2. Where necessary, checking the vented side (the header side) for leaks using the process described in the second aspect of the present invention. [0328] 3. While these processes are running visually inspecting the house for obvious sources of leaks. (dripping taps, running toilets, water marks on walls/ceilings etc.) [0329] 4. EITHERStep 1 (or 2 if needed) returns no leaks, in which case the house is free of leaks, [0330] ORStep 1 (or 2 if needed) signals there is a leak, but the visual inspection of Step 3 located it, in which an attempt to repair the leak can be made before re-running step 1 (or 2 if needed). [0331] ORStep 1 (or 2 if needed) indicates there is a leak but the inspection failed to find it. In this case the method of the third aspect needs to be run (or the 4.sup.th or the 5.sup.th with two sensors and the pump) to carry out its leak location indicating process.

[0332] The process outlined in the third and fourth aspects of the invention could be almost fully automated when used in conjunction with the device described in respect of FIG. 10 or 11 of the fifth aspect of the invention.

[0333] A control program, either run directly on the actuator 86 (the water release device), or run on a second device such as a mobile phone, tablet or computer that is in contact with the actuator, e.g. via the control board 84 or processor 82, 84 would release a pre-set volume of water, run through the process of the third aspect of the present invention to look for a leak, and then either update the operator of results or progress to releasing the next volume of water. The system could thus inform the operator when a leak has been found, or instruct the operator, or an automated pump 40, to pump up the system, or to let air out as needed. An example of such an arrangement is shown schematically in FIG. 12.

[0334] With this system, the operator 102 acts as follows: [0335] 1. Set up the actuator/water release device 100 downstairs for leak testing in accordance with the first aspect of the present inventionconnecting to, for example, a washing machine attachment point 70 and arranged, for example, for releasing water into a sink 96. In this embodiment the actuator/water release device 100 is adapted similar to the device shown in FIG. 11 and is arranged to communicate with an app on a phone 104here the one held by the operator 102. [0336] 2. Once connected, the operator (usually a plumber) turns off stopcock (or turns it on to re-pressurise, and then turns it off). [0337] 3. The method of the first aspect of the present invention is then carried out. If a leak is detected by that method, but cannot be found by a visual inspection, the operator 102 connects a pump 40 and pressure sensor 48or a combined/integrated unit combining the two, to a point on the water system as high in the house as possiblehere a top floor basin. In this embodiment the upper pressure sensor is in wireless communication with the water release mechanism, or optionally with a smartphone, tablet or computer, or other such controlling device 104 if the controlling device provides instructions based thereon to the actuator/water release device 100. [0338] 4. The operator can then trigger the leak location program of the third aspect of the present invention, or the fourth, or the fifth, on the water release device 100, for example using the controlling device 104. The program thus starts running and the two pressure sensors 48, 72 and the water release device 100 carry out the method of the third, fourth or fifth aspects of the present invention, preferably updating the plumber on progress, and preferably mapping the system as it goes. [0339] 5. If the program senses that the pressure is too low, the program can ask the plumber to pump more air in the system, or can command an automated pump to do so. [0340] 6. The water level 106 will continue to drop as the mechanism periodically releases volumes of water during the process, potentially in set volumes. [0341] 7. Finally, when the leak is found (either due to a sudden drop in pressure or because head is no longer falling) the sensor will alert the operator and tell them at what height the leak is located, and whether it is on a vertical or horizontal run of pipework. [0342] 8. The operator can then focus his inspections on appropriate locations, find and fix the leak and re-run the method of the first aspect of the present invention to check the system is now sound.

[0343] The present invention therefore provides useful leak detection methods, leak location methods that provide information about the location of the leak, such as height and pipe attitude (vertical or horizontal) and also leak flow rates. The present invention also provides integrated units or kits of parts for achieving these methods, and the system that operates in including manual or automated versions, and versions that can communicate with computers, smartphones or other mobile communicating devices, whether wired, wireless, local to the building or remote from the building.

[0344] Further Statements of Invention

[0345] 1. A method for testing for a possible water leak in at least a part of a water system, comprising:

[0346] closing all known water usage taps within the part of the water system to be tested;

[0347] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source (or sources), and any external replacement pressure source (or sources); and then

[0348] a) detecting a first pressure PO within the isolated part of the water system at a sensor connected to the part of the water system, waiting a period of time t and then detecting a second pressure P1 within the isolated part of the water system at that sensor; and

[0349] b) releasing a volume of water VR from the water system out of the isolated part of the water system via a vent in the isolated part of the water system, before then closing the vent, step b) further comprising detecting the pressures either side of that release at that sensor;

[0350] the method thus recording a) a pressure loss in the system over a period of time t caused by an unknown leak volume of water VL escaping the system and b) a pressure loss in the system caused by an approximately known or measurable volume of water released from the system;

[0351] the method further comprising using the pressure drop caused by the approximately known or measured volume of water VR to enable an estimate of the relationship between change in pressure in the system and the volume of water released to be established, and based on the relationship between the change in pressure and the known release volume, calculating an estimate of the actual volume of the unknown water loss volume VL based upon the recorded pressure loss in the system in the known period of time t.

[0352] 2. The method of clause 1, wherein the volume of the released water is measured as it is released.

[0353] 3. The method of clause 1, wherein the volume of the released water is measured after it has been released, by venting it into a measuring device.

[0354] 4. The method of any preceding clause, wherein step a) is carried out before step b).

[0355] 5. The method of any preceding clause wherein one of the two detected pressures of step a) is one of the two detected pressures of step b).

[0356] 6. The method of any one of the preceding clauses, wherein an estimated rate of water loss due to the leak is calculated by dividing a calculated volume VL by the time t.

[0357] 7. A method for testing for a possible water leak in at least a part of a water system, comprising: [0358] closing all known water usage taps within the part of the water system to be tested; [0359] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source or sources, and any external replacement pressure sources; and then [0360] a) detecting or determining a first pressure P0 within the isolated part of the water system at a sensor connected to the part of the water system; [0361] detecting or determining a second pressure P1 within the isolated part of the water system at that sensor after a period of time t, and; [0362] b) releasing a volume of water VR from the water system out of the isolated part of the water system via a vent connected to the isolated part of the water system, before then closing the vent and detecting or determining a third pressure P2 within the re-isolated part of the water system at that sensor; [0363] the method further comprising: [0364] calculating an approximate leaked water loss VL by using the following equation: [0365] VL=VR*P2(P0P1)/(P0(P1P2)) when using absolute pressures or [0366] VL=VR*(P2+P Atm)*(P0P1)/((P0+P Atm)*(P1P2)) if instead using gauge pressures, Patm being the atmospheric pressure where the sensor is located.

[0367] 8. The method of any preceding clause, wherein the period of time t is a period of time exceeding 2 minutes.

[0368] 9. The method of clause 8, wherein the period of time t is more than 5 minutes.

[0369] 10. The method of any one of the preceding clauses, wherein the time between taking the second and third pressures P1 and P2 is less than 20 seconds.

[0370] 11. The method of clause 10, wherein the time between taking the second and third pressures P1 and P2 is between 1 and 12 seconds.

[0371] 12. The method of any one of the preceding clauses, wherein the released volume of water VR is less than 80 ml.

[0372] 13. The method of any preceding clause, wherein the sensor is located at or near the bottom of the part of the water system being tested.

[0373] 14. The method of any preceding clause wherein the vent for releasing the volume of water VR is a part of a test assembly that includes also the sensor.

[0374] 15. The method of any preceding clause, wherein the method further calculates the rate of water release by dividing VL by t.

[0375] 16. The method of any preceding clause, carried out on a part of a pressurised or unvented water system that is usually pressurised by being connected to the mains, the stop cock or valve being the mains isolator stop cock.

[0376] 17. The method of clause 1 or clause 2, wherein multiple pressure readings are taken before and after the release of the volume of water, and then at least one line or curve fitted to the pressure values is extrapolated either forwards or backwards for such that second and third pressure values can be derived from the extrapolation that represent an instantaneous pressure change resulting from the release of the volume of water VR, said extrapolated values being used in any calculations in place of respective measured values thereof.

[0377] 18. A method for testing for leaks in at least a part of a water system, comprising: [0378] closing all known water usage taps within the part of the water system to be tested; [0379] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source, and any external replacement pressure sources; and then: [0380] a) detecting pressures within the isolated part of the water system at a sensor connected to the part of the water system at various intervals for a period of time t long enough to obtain a sequence of pressure readings; and [0381] b) releasing a volume of water VR from the water system out of the isolated part of the water system via a vent connected to the isolated part of the water system, before then closing the vent, step b) further comprising detecting pressures either side of that release at that sensor.

[0382] 19. The method of clause 18, wherein step a) occurs before step b).

[0383] 20. The method of clause 18 or clause 19 wherein one of the two detected pressures of step b) is one of the detected pressures of step b).

[0384] 21. The method of clause 18 or clause 19 wherein a gradient or decay rate of the pressure during the sequence of pressure readings is determined, and the method then uses that decay rate, and the pressure drop caused by the release of the approximately known volume of fluid VR to enable an estimate of the water loss to be determined.

[0385] 22. A method for testing for leaks in at least a part of a water system, comprising: [0386] closing all known water usage taps within the part of the water system to be tested; [0387] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source, and any external replacement pressure sources; and then: [0388] a) detecting pressures within the isolated part of the water system at a sensor connected to the part of the water system at various intervals for a period of time t long enough to obtain a sequence of pressure readings; and then [0389] b) releasing a volume of water VR from the water system out of the isolated part of the water system via a vent in the isolated part of the water system, before then closing the vent and detecting the pressures within the re-isolated part of the water system at that sensor at various intervals for a period of time long enough to obtain a second sequence of pressure readings.

[0390] 23. The method of any one of clauses 18 to 22, wherein the various intervals are approximately fixed and known intervals.

[0391] 24. The method of any one of clauses 18 to 22, wherein the various intervals are recorded and the pressures detected are recorded against the time when they were taken.

[0392] 25. The method of any one of clauses 18 to 24, wherein one or both sequences are extrapolated to approximate two pressures, at a single time-point, the pressures being a pre-water-release second pressure P1 and a post-water-release third pressure P2.

[0393] 26. The method of clause 25 further comprising: [0394] calculating an approximate leaked water loss VL by using the following equation: [0395] VL=VR*P2(P0P1)/(P0(P1P2)) when using absolute pressures or [0396] VL=VR*(P2+P Atm)*(P0P1)/((P0+P Atm)*(P1P2)) if instead using gauge pressures, Patm being the atmospheric pressure where the sensor is located. [0397] where if VL>0, it is determined that there is a possible water leak.

[0398] 27. The method of clause 26, wherein the first pressure PO is also extrapolated from the first sequence of pressure readings.

[0399] 28. The method of any one of clauses 18 to 27, wherein each sequence of pressure readings comprises at least 4 pressure readings, and more preferably at least 10 pressure readings.

[0400] 29. The method of any one of clauses 18 to 28, wherein the period of time t is a period of time exceeding 20 seconds.

[0401] 30. The method of clause 1, clause 18 or clause 22, wherein the system is re-pressurised to the starting pressure after the first of steps a) and b) has been performed before the second thereof is performed.

[0402] 31. The method of clause 30, wherein step a) is performed before step b).

[0403] 32. The method of clause 31, wherein releasing the water from the system in step b) is stopped when the pressure is at or still above the lowest pressure reading taken during time t.

[0404] 33. The method of clause 31 or clause 32, wherein the volume of water released in step b), up until the pressure is at or still above the lowest pressure reading taken during time t, is measured, that volume being an approximation of the volume of water leaked during time t.

[0405] 34. The method of clause 30, wherein step b) is performed before step a).

[0406] 35. The method of clause 34, wherein a fixed or measured volume of water VR is released during step b), with the pre- and post-release pressures being recorded, before then re-pressurising the system to at, or a little above the pre-release pressure and then recording how long (time t) it takes for the pressure to fall from the pre-release pressure to the post-release pressure without water being released, a leak rate then being approximately calculated as being VR/t.

[0407] 36. The method of clause 18 or clause 22, wherein the method comprises extrapolating forward a gradient or fitted curve of a pressure profile recorded against time from the sequence of pressure readings before water is released to give an estimated pre-release pressure at a time when a post-release pressure was recorded, and thus an instantaneous pressure difference at that time.

[0408] 37. The method of clause 22, wherein the method comprises extrapolating the gradient or fitted curve of the pressure profile recorded against time from the sequence of pressure readings after fluid is released to give an estimated post-release pressure at a time when a pre-release pressure was recorded, and thus an instantaneous pressure difference at that time.

[0409] 38. A method for testing for a volume V2 of a leak during a period of time t in at least a part of a water system, comprising: [0410] closing all known water usage taps within the part of the water system to be tested; [0411] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source, and any external replacement pressure sources; and then: [0412] a) detecting pressures within the isolated part of the water system at a sensor connected to the part of the water system at a start and end of the period of time t to obtain at least a start pressure P21 and an end pressure P22; and [0413] b) at a different time releasing a volume of water V1 from the water system out of the isolated part of the water system via a vent connected to the isolated part of the water system, before then closing the vent, step b) further comprising detecting pressures either side of that release at that sensor, the pressures being a pre-release pressure P11 and a post-release pressure P12; [0414] and calculating an estimate for the value of V2 using the data collected.

[0415] 39. The method of clause 38, wherein the calculation is performed using the following formula: [0416] V2=V1*(P11*P12)/(P21*P22)*(P21P22)/(P11P12) when using absolute pressures or [0417] V2=V1*((P11+Patm)*(P12+Patm))/((P21+Patm)*(P22+Patm))*(P21P22)/(P11P12) if instead using gauge pressures, Patm being the atmospheric pressure where the sensor is located.

[0418] 40. The method of clause 39, wherein an approximate leak rate can then be calculated by dividing V2 by time t.

[0419] 41. The method of clause 38, or clause 39, or clause 40, wherein step b) is carried out after step a).

[0420] 42. The method of clauses 38, wherein the estimate is calculated by calculating the area under a plotted curve for the pressure readings, the pressure being along the y axis and the time being along the x axis, and wherein that area, being an approximation, is corrected by applying a factor se, such that the volume calculated X is as follows: [0421] X=C x area under the profile [0422] where C is (A2/BA1) and [0423] B is ((P11+Patm)*(P12+Patm))/((P21+Patm)*(P22+Patm))*(P21P22)/(P11P12), the pressure readings being gauge pressures and Patm being the atmospheric pressure at the sensor.

[0424] 43. A method for testing whether there is a leak in at least a part of a water system comprising: [0425] closing all known water usage taps within the part of the water system to be tested; [0426] closing at least one stop cock or valve of the water system to isolate the part of the water system from its replacement water source (or sources), and any external replacement pressure source (or sources); and then [0427] a) taking several recordings of the system pressure dropping due to a suspected leak to give a set of suspected leak recordings, and [0428] b) setting an intentional leak in the system and taking several recordings of the system pressure dropping due to the intentional leak in addition to the suspected leak to give a set of intentional leak recordings; [0429] and comparing the two sets of recordings from steps a) and b).

[0430] 44. The method of clause 43, wherein the rate of the intentional leak is determined with a flow meter.

[0431] 45. The method of clause 43, wherein the rate of the intentional leak is determined by collecting it in a container for measuring its volume for a given time period shorter than the time the intentional leak is tested for.

[0432] 46. The method of clause 43, 44 or 45, wherein the intentional leak recordings of step b) occur after the suspected leak recordings of step a).

[0433] 47. The method of any one of clauses 43 to 46, wherein no pressure reset is provided between sets of recordings.

[0434] 48. The method of any one of clauses 43 to 47 wherein the method further comprises fitting lines of best fit, or curves, to both sets of recordings and considering how much faster the pressure drops in the intentional leak recordings compared to the suspected leak recordings.

[0435] 49. The method of clause 48, wherein the method comprises extrapolating the lines or curves to allow the angles of both lines to the time axis, or the pressure drops, for both curves to be compared from the same time-point on the graph.

[0436] 50. The method of clause 49, wherein the ratio of intentional leak angle (or drop) 2 to the suspected leak angle (or drop) 1 is taken to be the same as the known leak (VR+ the unknown leak VL) divided by the unknown leak VL, whereby the following formula is used to calculate the leak volume VL:

2/1=(VR+VL)/VL.

[0437] 51. A method for determining whether there is a leak in a part of a vented water system that has a header tank, comprising: [0438] closing all known water usage taps within the part of the water system to be tested and isolating that part of the water system from its header tank such that an overflow pipe above the normal water line provides the only installed vent for the part of the water system to be tested; [0439] attaching one end of a u-tube manometer 32 to the overflow pipe, such that the liquid of the manometer seals the overflow pipe, the other end of the manometer then being open to the environment; and [0440] observing whether the liquid in the manometer moves, movement suggesting the presence of a leak.

[0441] 52. The method of clause 51, wherein the liquid in the manometer is water.

[0442] 53. The method of clause 51 or clause 52, wherein the u-tube manometer is a length of silicon or rubber tube part-filled with a little water.

[0443] 54. The method of clause 51, 52 or 53, wherein the overflow pipe is for feeding over-pressurised hot water from a hot water cylinder back into the header tank for re-use.

[0444] 55. The method of any one of clauses 51 to 54, wherein the part of the water system is isolated from its header tank by a valve below the header tank, or by a bung in the bottom of the header tank.

[0445] 56. The method of any one of clauses 51 to 55, wherein upon detecting the suggestion of a leak, the method comprises the step of measuring the rate of vertical movement v of the liquid in the manometer, the method then determining a leak rate as v*A, where A is the cross sectional area of the manometer.

[0446] 57. A system for carrying out any one or more of the methods set out in any one or more of clauses 1 to 56.

[0447] 58. A pressure sensor module comprising a transmitter and receiver, a threaded cap, a venting tap, an actuator for the venting tap and a control board therefor, a pressure sensor, tubing or flow channels for connecting the pressure sensor and the venting tap to the threaded cap, all assembled into an integrated assembly.

[0448] 59. A kit comprising the pressure sensor module of clause 58 and a sensor and pump assembly.

[0449] 60. The kit of clause 59, wherein the sensor and pump assembly is an integrated unit, with a receiver and transmitter, and with a control board for the pump.

[0450] 61. The kit of clause 60, further comprising an app or program for a computer, tablet or smartphone such that the kit can be used to operate one or more of the methods of clauses 1 to 56.

[0451] These and other features of the present invention have been described above purely by way of example. Modifications in detail may be made to the invention within the scope of the claims appended hereto. In particular, features from one method, device, apparatus, claim (dependent or independent) or clause or aspect may beneficially be used with any other method, device, apparatus, claim (dependent or independent), or clause or aspectparticularly the non-essential or preferred features of each method, device or aspect, or the features within the dependent claims or clauses.