My boiler copper pipes are 15ml. Can I get a modern boiler to fit these?

Discussion in 'Plumbers' Talk' started by Robin Bailey, Oct 12, 2021.

  1. Robin Bailey

    Robin Bailey New Member

    Basically my current combi boiler is a Glow-Worm Flexicom 35CX. A plumber told me you'll need to replace this soon. He has 'sold' me a Baxi Boiler. He tells me I need a 22ml pipe to fit one. Gas meter is opposite end to house from boiler. He will have to run new 22ml pipework around the outside of the house. Boiler, new pipes & labour, quote is £4600 (inc VAT).

    Why not though get a boiler (are there any) to fit the current old 15ml piping & save the £2000 to fit new piping? Any thoughts & opinions would be gratefully received.
     
  2. andy48

    andy48 Screwfix Select

    1 I'm very surprised 15 mm pipework is sufficient to run a 35 kW combi like your current boiler without a significant drop in the working pressure at the boiler.
    2. The above makes me think that either:
    2a. Your boiler is struggling, and if you have one, any gas hob is likely to have lost / reduced flame when the boiler is on. OR
    2b. The main pipe run from meter to boiler is greater than 15 mm, and only the last metre or two is in 15 mm pipe.
    3. I'd suggest you get at least one other quotation, perhaps two, one of which is from British Gas.
     
    Robin Bailey likes this.
  3. exbg

    exbg Active Member

    £2K just for the gas pipe?

    The boiler is irrelevant. You need a certain amount of gas to produce a certain amount of heat, at a certain flow. There will be slight variations in efficiency between brands, models and systems - but not enough to allow a 15 mm gas supply.

    I am guessing that your existing system is a conventional stored hot water system, and your quite is for a combi? Largely, the increased pipe size is foe the water - due to a combi heating it as it goes through the boiler.

    But, £2K ?

    EDIT: only just noticed that yiu specified the boiler! Did not see it until I posted, when the other post popped up
     
  4. dcox

    dcox Screwfix Select

    I'd also expect you to need at least a 22mm gas pipe feeding your boiler but £2000 to upgrade it seems pretty high. Is it a difficult route eg do you need scaffolding?
     
  5. jonathanc

    jonathanc Screwfix Select

    Avoid British Gas. Have they explained precisely what’s wrong with the existing boiler. Personally I would not replace it until broken. Plus I would try looking at the gas pipe myself to see if it is 16mm all the way
     
  6. Robin Bailey

    Robin Bailey New Member

    Not a difficult route at all. He just needs to run it along the front & then side of the house. Don't Valliant Boilers fit into a 15ml pipe?
     
  7. Robin Bailey

    Robin Bailey New Member

    There's a leak at the top of the boiler, I saw it, limescale accumulating around hole. Boiler still works fine. He also said because of that leak small amounts carbon monoxide will be leaking out. It should not escape though.
     
  8. dcox

    dcox Screwfix Select

    I don't know any modern boilers that will run off a 15mm gas supply and the further away from the meter it is, the larger the pipe diameter will need to be.
     
    pppmacca43 likes this.
  9. Robin Bailey

    Robin Bailey New Member

    Also finding the pipework would mean ripping up carpet upstairs or kitchen floorboards
     
  10. dcox

    dcox Screwfix Select

    Roughly how long would the new route be?
     
  11. Mike83

    Mike83 Screwfix Select

    Boilers can be fed from 15mm but the boiler would need to be next to the meter.
    You need 22mm from the meter.
    In some situations you even need 28mm from the meter.
    Pipework could take half a day but £2000 is a joke.
     
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  12. Robin Bailey

    Robin Bailey New Member

    12-13 metres
     
  13. Robin Bailey

    Robin Bailey New Member

    His quote reads:
    heating materials for a new boiler replacement including gas supply upgrade £1900

    Services: £2000
     
  14. pppmacca43

    pppmacca43 Super Member

    Get a couple more quotes and u will see if it is fair, seems a bit expensive to me but hard to say without seeing exactly what’s involved. I wouldn’t read that quote As £1.9k for just the gas supply upgrade though, to me that looks like that includes the boiler and all materials in that section.
    Also, no chance of running a modern combi boiler on a 15mm pipe. Personally not a fan of Baxis, I’d go for a Worcester or Vaillant or even a viessman.
     
    Robin Bailey likes this.
  15. andy48

    andy48 Screwfix Select

    May I suggest that before you do anything else you try and fins out what size the gas pipe run is from meter to boiler. It may be 15 mm at the boiler, but could well be bigger for a substantial part of its length. If it is an older property for instance, there may well be a 3/4" steel pipe to the kitchen, which then branches off in 1/2" each for a boiler and cooker.
    While a run ALL in 15 mm clearly won't be enough, a large length of wider pipe with 15 mm at the boiler end only may be OK.
     
  16. dcox

    dcox Screwfix Select

    That £1900 is for the boiler itself, any fittings and the materials for the pipe upgrade. Then £2000 labour to do the work.
     
  17. Robin Bailey

    Robin Bailey New Member

    Means ripping up alot of carpet or floorboards as the pipe runs the length of the house. I understand why the plumber didn't look for it, as it's a hassle to investigate further.
     
  18. dcox

    dcox Screwfix Select

    It would be interesting to see what the supply is like with your current boiler. With the boiler running at full power there should only be 1 millibar difference in pressure between the meter and the boiler. If it’s more than that then your pipework needs upgrading. That’s assuming your new boiler will be 35kw or more. Any GasSafe person should be able to check that for you.
     
    Robin Bailey likes this.
  19. jonathanc

    jonathanc Screwfix Select

    Really? Post a pic up of the line scale and leak please

    first off if the boiler is leaking carbon monoxide it is not acceptable for a gas safe engineer to leave it leaking. Second flue gases are acidic not alkaline so I would not expect limescale from the flue area.
     
  20. Robin Bailey

    Robin Bailey New Member

    I'll upload a pic tomorrow. Carbon Monoxide comment could be just to persuade us into upgrading.
     

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