2mbs Gas Leak

[ruden]

Hello, I recently bought a property and had British Gas come to service my boiler as I noticed the ceiling above it was slightly black and the hot water kept going on and off.

It passed all the service but was told I have a small gas leak of 2mbs so as it was in tolerance it didn't need to turn off my gas, and it was up to me if I choose to do anything about it.

I was quite worried but after some avid googling I realise 2mbs is a trivial amount of gas, I have a carbon monoxide alarm and a natural gas alarm which have never gone off and I can't smell gas. What should I do next? Should I get a second opinion and someone to fix it? Is it worth the cost?

 

[CBW]

No, 2mbar drop with no smell of gas is nothing to worry about and personally think it’s a bit of scaremongering. A carbon monoxide alarm will not sound from a natural gas leak. If you have a natural gas alarm which hasn’t sounded then it’s likely through the appliance. It could even be faulty testing equipment.

 

[ruden]

Yeah it seemed that way, especially because they issued me a safety warning notice and I had to sign a disclaimer that said 'I refused' to turn off my mains gas... I assume it was just to cover themselves.

 

[fixitflav]

No, 2mbar drop with no smell of gas is nothing to worry about and personally think it’s a bit of scaremongering. A carbon monoxide alarm will not sound from a natural gas leak. If you have a natural gas alarm which hasn’t sounded then it’s likely through the appliance. It could even be faulty testing equipment.

For my enlightenment, what is this test? Does it involve closing a valve at the meter, then checking pressure drop downstream (over a given time) or what?

 

[CBW]

Yeah it seemed that way, especially because they issued me a safety warning notice and I had to sign a disclaimer that said 'I refused' to turn off my mains gas... I assume it was just to cover themselves.

Oh dear oh dear, that is very poor, and unnecessary. Unless you’re being uneconomical with the truth, a 2 mbar drop, no smell of gas doesn’t need a warning notice or for gas to be turned off! It’s within industry tolerance (they’ve told you that already). Personally, I doubt it would cover themselves because it’s a permissible drop, as I said, with no smell of gas. Unless the drop was on the appliance? Could you elaborate more? BG don’t usually carry out a tightness test as it’s not needed on a service.

 

[CBW]

For my enlightenment, what is this test? Does it involve closing a valve at the meter, then checking pressure drop downstream (over a given time) or what?

A tightness test, which is usually done at the meter yes, and yes checking for a drop over a 2 minute period after Letby and temperature stabilisation.

 

[fixitflav]

after Letby and

Thanks, but I don't get that bit!
So a leak could be from a fitting into the room, or through the boiler gas valve?

 

[CBW]

Thanks, but I don't get that bit!
So a leak could be from a fitting into the room, or through the boiler gas valve?

Letby is a test before the tightness test, if the ecv is passing, then it’s renders the TT void. If the fitting was into a room I would expect someone with a sense of smell to smell it. Yes, you can get a gas valve passing at a boiler or a fitting behind a chimney leaking with the smell escaping to atmosphere.

I had one last week, customer smelled gas in the kitchen esp went out, found it to be on the hob and capped the gas. I carried out a tightness test, solid - no drop, after some further investigation the hob tap wasn’t closing properly, but after being used.

 

[RandomGrinch]

So a leak could be from a fitting into the room, or through the boiler gas valve?

Or from the pipework itself. Here's my lead gas pipework, with crimps where branches used to extend to gas lighting on the walls - the joys of a Victorian property!

 

[fixitflav]

Letby is a test before the tightness test, if the ecv is passing, then it’s renders the TT void. If the fitting was into a room I would expect someone with a sense of smell to smell it. Yes, you can get a gas valve passing at a boiler or a fitting behind a chimney leaking with the smell escaping to atmosphere.

I had one last week, customer smelled gas in the kitchen esp went out, found it to be on the hob and capped the gas. I carried out a tightness test, solid - no drop, after some further investigation the hob tap wasn’t closing properly, but after being used.

OK, nothing to do with Lucy Letby then! I thought it might be a case of predictive texting as she was in the news.

 

[ruden]

Oh dear oh dear, that is very poor, and unnecessary. Unless you’re being uneconomical with the truth, a 2 mbar drop, no smell of gas doesn’t need a warning notice or for gas to be turned off! It’s within industry tolerance (they’ve told you that already). Personally, I doubt it would cover themselves because it’s a permissible drop, as I said, with no smell of gas. Unless the drop was on the appliance? Could you elaborate more? BG don’t usually carry out a tightness test as it’s not needed on a service.

I wasn't in the room the whole time, so I didn't see everything he was doing/nor am I very technical. But I did see him measuring something at my gas meter with a timer and said 'oh that dropped slightly' so I assume that's where he saw it. He didn't really mention any other details - in hindsight maybe I should have asked more questions

 

[CBW]

I wasn't in the room the whole time, so I didn't see everything he was doing/nor am I very technical. But I did see him measuring something at my gas meter with a timer and said 'oh that dropped slightly' so I assume that's where he saw it. He didn't really mention any other details - in hindsight maybe I should have asked more questions

Measured at the gas meter - then I refer back to posts #2 and #5.

 

[CBW]

OK, nothing to do with Lucy Letby then! I thought it might be a case of predictive texting as she was in the news.

No! Sorry, I usually ad a hyphen, so let-by.