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Too many boilers for the 22mm pipe

Discussion in 'Plumbing and Central Heating' started by StephenStephen, 29 Oct 2018.

  1. StephenStephen

    StephenStephen

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    I'm slightly flummoxed to find out today that our home heating system is dangerous - we've 2 gas boilers and a gas water heater, which have all been here for many years, serviced many times, and have been told today that because their combined rating is so high, there is a danger of the gas pressure in the pipes dropping far enough to cause an explosion.
    I'm slightly confused by the whole thing, especially as so many engineers have serviced them over many years.
    I guess I'll have to look into it in more details, see what our options are, but just wanted to get a sense of whether this is common? and what is often done in this circumstance? - so far we seem to have been offered more problems than solutions.

    Cheers all, thanks for reading, and for any thoughts, Stephen

    EDIT More specific details and pictures in post 9 below. ...and my apologies - The engineer did not specifically use the word: 'explode'
     
    Last edited: 31 Oct 2018
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  3. just pumps

    just pumps

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    First off I`m not gas that said from what I`ve read over the years the appliance`s wouldn`t work as they should, can`t see a risk of explosion but wait to be enlightened.
     
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  4. Dan Robinson

    Dan Robinson

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    They won't explode, but they won't burn gas safely.

    If they used the word "explode" get someone else in to advise on what to do next.

    Undersized pipework is common.
     
  5. ianmcd

    ianmcd

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    They wont explode, as said they MIGHT not burn safely depending on what boilers they are, if they are fully modulating they just wont get to max rate, not correct but dont stress out too much, they certainly will not explode
     
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  6. muggles

    muggles

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    ...and you seem to have offered more words than information.

    What power rating in kW are your appliances? Makes & models? Natural gas or LPG? Length of gas pipe run?

    As above, unlikely to explode, but it sounds like your gas pipe may be undersized. If you can provide the requested info, we can advise on the possible extent of the problem
     
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  7. StephenStephen

    StephenStephen

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    Thanks all - yes I need to gather more information to share with you - details of boilers and pipework etc - I'll get onto that and get back to you, thank you for your help so far.
     
  8. ScottishGasMan

    ScottishGasMan

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    As said, explosions are't cause by undersized gas pipes. But its very very possible running 2 boilers and a water heater off 22mm gas pipe could be a case for classing them as "At Risk" and advising a pipe upgrade.

    It's not part of the mandatory checks when servicing/working on appliances to check the supply pressure at the appliances, but it is when installed, so realistically 1 person can fit them wrong, and no one actually checks the safe inlet working pressure there after.
     
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  9. John D v2.0

    John D v2.0

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    They can't say it's unsafe without checking the combustion of the appliances, however if the pressure drop is above standard they can say that
     
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  11. StephenStephen

    StephenStephen

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    more hopefully helpful info and pics

    The system

    -The natural gas rises up to the meter in a 22mm pipe pic1
    -It comes out of the top in a 22mm pipe pic 2
    -After 100 mm it splits to 2 22mm pipes - pic 3

    -Pipe 1 feeds a Main Medway Super gas fired water heater G.C. No: 52 476 39 (This is currently fed by 22mm pipe which goes down to approx 14mm)

    -Pipe 2 feeds:
    - A gas cooker and oven
    -A Glowworm hideaway 50 boiler: info on the boiler: supply pressure 20mbar, heat input 18.79 kW (this is fed by 22mm pipe which goes down to approx 14mm for the last couple of feet) pic 4
    -A Thorn 44/54 Boiler: info on the boiler: heat input 19.55 kW, burner pressure 17.1 Mbar (This is currently fed by approx 14mm size pipe though an auxiliary gas meter (not read by anyone)) pics 5-9 This boiler is in a small outdoor shed/cupboard.

    Problem 1
    When we just had our boilers serviced, we have been told that because of the combined rating of the appliances, there is a theoretical danger of the gas pressure dropping below 15% at which point it could become combustible. Whilst the engineer did not use the word 'explosive' and was slightly vague about the details of the consequences, he certainly suggested that it could be dangerous enough to cause something to me or my family that he wouldn't want on his conscience. He didn't refer to any gas pressure measurements made at the appliances, and I think he was saying that he would need to check measurements with all appliances running but couldn't do that because it might be dangerous. He didn't offer any solutions or suggestions, other than that to trace the pipework from the meter to the Thorn boiler would be difficult.
    Any thoughts or suggestions?

    Problem 2
    This seemed more straightforward to me - the engineer pointed out that the seals had perished on the Thorn Boiler (photos 6 - 9) and that they could be replaced, but he would need to get hold of something to adapt as the original seals are not made any more.
    He seemed to be suggesting that this would be a temporary fix because:
    -The boiler is old and probably not worth fixing
    -The original parts are not available so it would only be a temporary fix
    -We'd still have the problem of theoretically too low gas pressure

    He has marked it as dangerous and not to be used in the meantime

    What I'm wondering about this is:
    -Whether the Thorn 44/54 is a boiler that is generally seen as being worth keeping going? I don't want to replace it if it's not necessary.
    -I'm slightly confused about this 'temporary' seal fix - if the boiler is worth keeping going, should I be insisting on a 'non-temporary' fix, and what might this be?

    Sorry for the long post, thank you all for your help so far - any thoughts welcome, cheers, Stephen
     

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  12. StephenStephen

    StephenStephen

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    Any thoughts? Have I supplied enough info to make sense?
     
  13. ianmcd

    ianmcd

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    you are plodding away with some really old appliances there , why not get some quotes to replace the lot with a correctly sized supply instead of trying to put a bandaid over a broken leg
     
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  14. StephenStephen

    StephenStephen

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    Thanks - that's helpful - is it that they're more likely to break down and cost more money because they're old, or is it that they will be using more gas than a more recently made machine? The three areas of the building are quite separate and have different heating and hot water needs - Do you think it would still make sense to have one machine to try to do everything?
     
  15. ianmcd

    ianmcd

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    sorry you read my reply wrong, I meant you have some old appliances there , most of which have been great appliances in their time but they are not endless and are coming to the end of their lifetime, I meant get a professional in to advise you on your options rather than wasting money just altering the gas supply, you may be able to do everything you want with one appliance , you may not , unless someone is on site and sees what you require then its not the correct advice , most will come and quote for free so get a few quotes and move from there
     
  16. MrBenchmark

    MrBenchmark

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    I wonder who illegaly resited the meter?? Copper on the live side!

    Or is that the secondary meter??
     
  17. StephenStephen

    StephenStephen

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    That is the primary meter - I'm ignorant as to what you're referring to - could you say more?
     
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