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Hello Guys,

Wondering if anyone can help me. And before anyone asks, I am fully ACS qualified and fully Gas Safe Registered.

Was called to a job a couple of days ago just for a routine landlord safety check and during the let by and tightness test I found a very small but continuous leak on an installation. The leak itself took longer than the permitted four minutes and there was no smell of gas with the leak actually taking about 10 minutes to fall from 20.77mb to 16mb with the incremental drops at about 0.02mb.

Now, my initial test was at the meter. I then disconnected the free standing cooker from the supply and isolated the boiler (Ariston Microgenus 24HE ) and run the test again with pretty much similar if not exacts to those listed above.

Now here where it gets strange. I used my electronic manometer at the meter test point whilst having a second electronic manometer, in the form of my flue gas analyser connected to the test point of the boilers gas valve. Beneath the boiler, about 60cm there was an isolation valve which I had in the off position at the same time the gas meter ecv was also off. I pressurised the system via the meter ecv up to the boilers isolation valve and monitored the monometer at the boiler test point and there was no change in the pressure reading telling me that at least the boiler isolation was not letting by at all and no gas was entering the boiler however, the gauge at the meter was still showing this minute drop in pressure which led me to conclude that the pipe work between the ecv and the isolation valve under the boiler may have been at fault.

Just to add, I did also check the bayonet connection after disconnecting the cooker using LDF and there didn't appear to be any problems.

I de-pressurised the system, reattached the gauges to the meter and boiler test points with the isolation valve under the boiler being in the off position. Pressurised the system fully, again the gauge at the meter showing a very small but continuous drop with the second gauge showing zero pressure. I opened the boilers isolation valve pressurising the 60cm pipe work between the iso valve and the boiler to 20mb, shut it off. Again there was a small but continuous drop with the increments being in the hundreds of units with the time between each significant drop being quite lengthy.

It is possible that the iso valve under the boiler is the culprit but i did check this with the aid of LDF and couldn't see any activity so was wondering if the leak was at the boilers gas valve with perhaps the low gas, pilot solenoid not being fully closed off accounting for the small leakage but this might be a misinterpretation as the gauge at the meter was still showing a slow but continuous pressure drop simultaneously ! Another thing I did notice that at intervals, the speed of the drop did increase but again this only registered in the hundreds of units.

Could it be the gas valve solenoid, the pipe work or both.

Save to say, I did isolate the supply completely and issued a advice notice and label indicating an immediately dangerous situation and the landlord called Transco.

Anyone had any similar experiences or can offer advice on my experience ?

Cheers in advance
 
If the leakage rate was the same when the boiler ISO was shut as it was when it was was open and the gas valve charged up I would think it possible but unlikely that it is at that end, as that would mean the ISO was leaking at exactly the same rate as the gas solenoid was passing, possible but not likely
Apologies if I'm missing a bit from your post, but were the leakage rates the same with ISO open as it was when shut? If yes then does that not mean that the ISO is shut and the gas valve isn't passing, again proving the leak is on the carcass somewhere?
What was the leakage rate with appliances connected after 2 mins? ( what I'm getting at, was if less than permissible with no smell or report of smell, why did you shut the appliances and ID the installation?) I expect pelters for my last comment haha
 
Why was you testing for ten minutes? And also what meter was you testing on?
 
Hi its prob sucking eggs but did you swap gauges over or independently test, also faulty hose between nipple and gauge a possibility. With such a small drop sounds like you may have to get a sniffer on the job and do some tracing.
 
Personally I only use a u guage for soundness testing and electronic gizmo gadgets for commissioning, I'd follow the correct test procedure, it either fails or it doesn't, if it failed I'd start isolating appliances and test if its still dropping I'd double check my u gauge isn't playing up to save me looking stupid and capping a sound installation which is what happened to me when I last used my gizmo gadget for a soundness test.
 
I wasn't deliberately testing for ten minutes as I know only four minutes are required. After the four initial minutes, I wanted to ascertain the whether the rate of drop increased or decreased given a given time frame.

I was testing on an E6 meter, however I don't see why that should influence the test !
 
Yeah, I did swap the gauges just to see if it might've been a problem with the devices but the results were similar no matter what point the gauges were tested to. As I said originally, the actual drop was particularly small and maybe not have been perceptible on a water gauge compared to my gauges which are sensitive two decimal places.
 
I wasn't deliberately testing for ten minutes as I know only four minutes are required. After the four initial minutes, I wanted to ascertain the whether the rate of drop increased or decreased given a given time frame.

I was testing on an E6 meter, however I don't see why that should influence the test !

The meter size decides the permissable drop
 
Yeah, I did swap the gauges just to see if it might've been a problem with the devices but the results were similar no matter what point the gauges were tested to. As I said originally, the actual drop was particularly small and maybe not have been perceptible on a water gauge compared to my gauges which are sensitive two decimal places.

So you are saying you ID'd and capped an installation that you should/could have passed?
Who's going to pick up the bill for your decision? I had asked earlier what was the drop after the 2 minute test with appliances connected?
 
That's pretty bad! If there was no perceivable drop and u capped off??? I wouldn't have posted. Farting can cause 0.10mb drop, hot cup of tea on meter causes .25 rise.
 
I asked what meter you was testing on because an E6 meter allows 8mb drop with no smell of gas so your tightness passed as far as as im concerned . You was only there to do a landlord checkwhich just required noting on your cp12. Why make life harder for yourself doing unnecessary things? Its a pass or fail .
 
sounds like a pass to me. id use a water gauge for your tightness tests tbh, digital gauges can be to sensitive imo for this job.
 
sounds like a pass to me. id use a water gauge for your tightness tests tbh, digital gauges can be to sensitive imo for this job.

I agree, no matter how many times I try I cannot demonstrate a TT using the Kane 455, end up,losing the tattie with it and going back to u gauge
 
Don't suppose you tried capping meter and testing that, had a drop on a new install with a mate at a new build. We cut up floorboards and all, turned out brand new meter was fk,d
 
Did you put a disk in the meter and isolate the consumer side? And then test?
 
Can I just point out a tightness test is not for 4 minutes, its 2 minutes

1 min let by to check ecv
1 min temp sabalisation
2 min test period
 
Can I just point out a tightness test is not for 4 minutes, its 2 minutes

1 min let by to check ecv
1 min temp sabalisation
2 min test period

I'd argue the toss on that but then one installation I tested recently was 23m3..........
 
Lol, had to use the digital gauge to get the test time down to 5 minutes!
 
Mate, it was 44 minutes on the J gauge, maximum test duration 45 minutes! Too close for comfort!

Would've been 44 minutes let by, 44 minutes stabilisation and 44 minutes TTD.

My 510 brought it down to 5+15+5
 
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