What happened here then?

[GWAYGWAY]

I have had to replace my gas regulator and then I also fitted new stainless pigtails. In order to check for leaks I made a water tube manometer and plugged into the external gas point, this showed a 13 inch head of gas, then with the bottles turned of it stayed where it was for 2 hours without moving, then when I was not looking it dropped to 0, nothing happened and everything was off, so why did it do that???? I have done it again and the head stays the same height. I bled a bit off and it still stays the same height so no leaks? Stayed the same heigh so what happened???? It confuses me.

 

[gasgas]

The official test is to connect the manometer, turn off the bottle tap and if it doesn't drop in two minutes, it is tight. I.e there are no leaks. It may be that when you weren't looking the fridge turned itself 'on', the gas in the pipework went to the fridge burner which lit, then went out when the pipe gas was used. That's my guess. Your test sounds perfectly valid and your gas system is fine. Well done for doing it, most people don't bother.

 

[Geek]

There are two possible faults:

1. the shutoff valve could be leaking - test this by shutting off the valve, then letting some pressure out and watching to see if the pressure creeps up again with the valve still off.

2. Gas could be leaking out of the system - test this by turning everything off with the shutoff valve on, them turn the valve off and check that the pressure stays up.

Two things to beware of:

1. cold gas in warm pipes expands and can increase pressure. Or vice versa.

2. It's easy to forget some appliance that might draw a little gas. Be sure they're all off, but don't turn their inline isolation valves off: you want to test that the appliance taps aren't leaking.