Can't comment on the pressure gauge jumping apart from some flexibility in the heat exchanger maybe.
But just to get back to basics. Please confirm....
1. Your water meter is going around and around when you are not using water.
2. The water meter stops when you turn off the stop-cock
andytw
Hi Andy,
1. Correct.
2. Correct.
Thanks
P.S.
I doubt it's important but just for the record - we have two stop cocks: old brass one (many turns to close/open; was at the property when we moved in) and a new one (one 90 degree turn to close or open) fitted by our builder. All the "experiments" I've reported so far were done with using the new valve.
Given the above-and I know this has been suggested already- but just to make clear one option, or confirm that it has been done.... List and isolate all sources of use. Get person watching (definately stopped) meter on a mobile phone and (mid call to them) visit each (prior isolated) appliance to hear on changes at meter as you briefly turn on iso valves. Eliminate options. Report back?
If any items cannot be isolated, consider fitting ISO valves!