"RobertL" wrote in message
...

We are about to let our house and the landlord's gas safety test has
detected a fault. When the system is shut off from the main the
pressure after at meter drops by about 0.01 mB per second. I think
the pressure was around 20 mB. It was a digital meter.

Now, the first puzzle is that BG and another plumber both passed the
pressure test a year ago when the meter was moved and some pipwork
rerouted. Nothing has been done to the gas system since then.

The second puzzle is that he said that when he measured it, the
pressur "held OK for a bit and then started to drop".

The house has a mix of copper and old iron gas pipes, all are capped
except at the boiler. It's a 3 bed end terrace.

Any thoughts?

.
Robert

I had exactly the same failure when my tame plumber came to fit a new pipe
for the gas cooker in my revamped kitchen. After some head-scratching, we
arrived at the open-flame gas fire in the lounge (one of those things with
ceramic 'coals' in it.) At some point during the summer season, the pilot
had gone out, so the auto cut-off had dropped the gas supply. However, the
valve hadn't *quite* closed solidly, allowing a tiny amount of gas to
continuously seep past it and out of the pilot jet. The plumber said this
was quite common, and happened because the valve was not a regularly
'exercised' device. He gave it a sharp rap with the butt end of a spanner,
and you could actually hear it click. The pressure test then held ok.

Arfa