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Discuss Gas pressure question in the Gas Safe Register Forum - Public Forum area at UKPlumbersForums.co.uk.

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  1. Wormwood

    Wormwood New Member

    Part of the pavement/road was dug up last year - I didn't pay any attention to it though, so I'm not sure if it was gas, H2O or electricity.

    As far as I know, no other house in the road has had to resort to swapping to a 22mm pipe when they've had a new boiler fitted - hence my suspicion of something partially blocking my pipe, either upstream or downstream of the meter. Or, the meter itself is restricting gas flow (more than meters normally do).

    I'm not tempted to DIY it. I know what gas can do when it goes off!

    How else can they check if the pipe is partially blocked then?

    The chap who tested the pressure at the boiler did not test the pressure at the meter.

    The other chap tested the pressure at the meter (when he changed the regulator) but did not test the pressure at the boiler.

    In other words, both points have not been tested at the same time. Hence, I have no idea whether the drop from meter to boiler is more or less than 1.5mb. All I was told is that the pressure at the boiler end of the pipe is too low and a 22mm pipe would solve it.
     
    Last edited: Jul 16, 2017
  2. Wormwood

    Wormwood New Member

    My current plan is this.

    1. Ask the supplier to change the whole meter for a new one.

    2. Get someone in to measure the gas pressure in and out of the meter. Then measure the working pressure at the boiler.

    Sounds reasonable to me.

    :):):)
     
  3. snowhead

    snowhead Well-Known Member

    I'm out after this, but you'll end up with 22mm up to the new boiler whoever fits it and whatever size it is.

    Has anyone checked whether you have Earth Bonding to the gas pipework?
    Even tho' your boiler may have worked fine without it for 30yrs, you'll still need to have it if it's not in place.
     
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  4. Wormwood

    Wormwood New Member

    Why will I end up with 22mm?

    Yes, there is earth bonding on gas & water pipes and it's ok (it was checked & certified by an electrician in June).
     
  5. king of pipes

    king of pipes Trusted Plumber GSR

    Do not attempt anything on your gas supply contact a GSR he will diagnose your problem and if you should need a vist from cadent he will arrange another vist . cheers kop
     
  6. Wormwood

    Wormwood New Member

    See post 16 paragraph 3 :)

    I've worked on a gas rig in the North Sea so I'm not tempted to do anything myself gas-wise.
     
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  7. Wormwood

    Wormwood New Member

    I still don't see why the pipe has to be 22mm as long as the pressure drop is within regs (as per Shaun and Snowhead's advice).
     
  8. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    The only time is if it's out of spec e.g. More than allowed pressure drop
     
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  9. GH77

    GH77 GSR Top Contributor!!

    If the old boiler has a pilot light then it will be an atmospheric burner, it will only require enough gas pressure to make Burner pressure, for example 10mb, your new boiler will be a zero governer, these ideally require 20mb inlet working, but depending on the boiler can be as low as 14mb, more usual is 16.5 to 18mb. If your meter regulator is supplying 19-21mb working pressure and you then don't have enough working pressure at the boiler, then your Pipework is undersized. The engineer who carried out the survey should have carried out a pipe sizing exercise to determine if the existing pipe is suitable, he has said it is not and requires upgrading for a new boiler, if he hadn't done this and just fitted a new boiler, he would be liable to correct the installation error at his own cost. Sounds like he is a professional doing a good job, I would suggest you follow his advice
     
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  10. king of pipes

    king of pipes Trusted Plumber GSR

    Providing the pressure drop is within the regulations then you are ok , if not then it will need to be addressed i am afraid ,when you upgrade any proffesional Gsr would upgrade a 30year old gas supply when fitting a new modern condensing boiler any debris rust or otherwise would not be a issue then and you will have a supply correctly sized and which will last the life of the boiler and longer regards kop
     
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  11. Wormwood

    Wormwood New Member

    Ok, thanks Shaun - I understand. What do you think of my plan in post 17?

    Thanks for that explanation GH77.

    The pipe coming out of the meter is 22mm, so it reduces to 15mm somewhere inside the house. It would be really good if I could find out exactly where - maybe it's right next to the boiler (the 15mm disappears into the plaster so I can't tell).

    Btw, there's a rust-coloured deposit all over the inlet pipe to the meter. I wonder if it's got inside the pipe as well. Hmm.

    Ok, thanks Kop.
     
  12. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    I would get no 2 done first and see what you get
     
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  13. Matchless.plumb

    Matchless.plumb Trusted Plumber GSR

    I think rules have changed 1mbar drop max. From meter to appliance 1mbar drop only!
     
  14. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Still 1.5mbar max
     
  15. GH77

    GH77 GSR Top Contributor!!

    IMG_5893.PNG Depends where your pressure test point at the boiler is, whether you've got one before the boiler or using the test point on the Gas Valve, picture paints a thousand words
     
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