On Nov 13, 6:05*pm, "Tim" wrote:

If you bought your own manometer (B&Q sell them) you could rule out leaks at
the nipple. *If it turned out to be that then you could probably ask for a
retest.

THat's an interesting idea. In fact I'm havoing another trusted
plumber in to retest. I've cancelled the proposed repiping of the
firt guy.

I worked out that to drop 0.01mB per second it must vent many litres
of gas per day. I woudl expect to be able smell that (we live in the
house at presnt and have done for many years). There is no smell
inside the house or under the floor where the pipes are routed.

Roert