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Yesterday I got a call from the other half to say that there was water dripping from the loft hatch back at mill stone manor! We have a procedure for leaks, only used once before, and she had already done everything to prevent any further loss so the situation was calm and the amount of water was quite small - damp carpet. Had we been out it would have been another matter! Long - story short, I came home and got into the loft and saw that the water was coming from the pressure set pump's primary pressure switch, a pin hole in the diaphragm housing! I soon had it apart, ordered a new switch as a spare and machined up a new diaphragm housing, fitted it and tested it. So me thinks - job done! Overnight I have been wondering how the control system for the pressure set could be adapted to detect small leaks. It already has protection, trips, if the pump runs too long in trying repressurise the system or if the pressure rises above 1.2 bar. Neither of these would protect against a small leak. So the challenge is to come up with a way of detecting very low, constant, flows such as a dripping tap or our pin hole. Several ideas come to mind, very sensitive flow meter and / or analog pressure sensor watching the slow reduction in pressure come to mind but neither would be fool proof and might well be impractical. Any thoughts? A bit of background if it helps: We have the worst water pressure anywhere and we can get about 2L/min out of the main tap if nobody else on the hill is running anything. So about 20 years ago we put an extra tank in the roof (total of 400L), a UVC, a 100L expansion vessel and a pressure set into the loft which pressurises the cold water to 1Bar which then feeds the UVC. This approach means that the Hot and cold water are always at the same (roughly) pressure so the thermostatic showers work really well and at full bore are very refreshing. The pump will happily deliver 70L / min against 1 Bar and the expansion vessel (on the cold side - but there is a small one on the hot side as well to allow for the expansion of the hot water as it expands) ensures that you get several minutes of flow to the showers before the pump cycles the pressure up with a hysteresis of about 0.4 Bar.