Hi there, I've recently installed an under sink water heater with expansion controls. I've got the mains going through an isolator valve then into a pressure reducing valve. This seems to be where my problem is. When I open the isolator valve the water flows for a few seconds, the taps work then "THUNK". The water is cut off. If I open the isolator very slightly it works for a bit longer but soon cuts out again. Could the mains pressure be too low or high for the PRV?
Thanks for any help. The local plumber here has recently retired.
Thanks for any help. The local plumber here has recently retired.