the only iso valve on the gas line (closest the boiler eg left one) is not allowed but the test point is for working standing pressures (right/ lowest on the gas pipe)
A leak I was called to after a plumber repaired it 2 weeks ago
He had just resoldered the reducer without removing and cleaning etc and when he couldn't stop the drip he simply left a deep sandwich box underneath it (gatepost guarantee) which took 2 weels to fill and overflow through the ceiling again
Also in the next joist was this
http://images.tapatalk-cdn.com/16/03/05/8ad698b25af887781866c2e9cf0e4a40.jpg[/IMGpair of flexis joining some rad drops, which were also leaking
Whilst draining down I managed to give his car a wash at the same time (ends of hoses jumping around due to air in system)
[IMG]http://images.tapatalk-cdn.com/16/03/05/d8fb9ed5156c5f4d536ae792928f101d.jpg
Cut out the 28mm tee and replaced, also got rid of the flexis and rigid piped it
Was only supposed to be a leak on a rad ffs