Discuss Suspected Leak in Hot Water system vs Cylinder behaviour? in the USA area at PlumbersForums.net
My only issue with I understanding if it is the combination PRV/NRV on the input to the tank, where is this water going? What goes in should come out I suppose..If the water meter stops when the isolation valve on the combination valve is closed and no water is being used in the property? then this points to a leak you have tempreture and pressure relief valves fitted to the cylinder I would be monitoring these especially at heat up times do you have any idea what your incoming
water pressure is ? water pressure can certainly rise over night and a faulty combination valve is quite possible, your cylinder is still under warranty but you must determine what and where the problem is and where you losing water . Kop
Yeh it's a sealed system.IMO, a pressure gauge is the first requirement to track down the problem.
What we havn't mentioned is a holed heating coil but if the heating system is sealed then eventually if the cylinder pressure is consistently higher than the coil pressure then the PRV will eventually lift on the boiler, however if the two pressures are very close and at times the cylinder pressure may be lower than the coil pressure, in this case water will be shunted back into the cylinder thus keeping a balance.
If the boiler& system is open vented then eventually the F&E tank should start overflowing.
Yeh boiler pressure only appears to rise when there is heating or hot water demand and it's running. It does rise to around 2bar which I always thought was quite high from a standing start of 1.2bar (1.8bar if hot water demand and 2bar for the radiator circuits).Keep a eye on the boiler pressure when off, it should fall slowly and should not rise under any circumstances if the filling valve is shut and if there is no cylinder coil leak.
You said you're an electrical engineer so perhaps the following analogy might help.I also still can't get my head around the declining 'leak rate' throughout the day.
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