Minimum distance or run of copper before plastic from boiler for Worcester Bosch Combi

Discussion in 'Plumbers' Talk' started by sfmanus, Jul 21, 2019.

  1. sfmanus

    sfmanus Member

    Hello there,

    Worcester Bosch have told me that a minimum distance of 60cm of copper is required before running plastic.

    Can anyone tell me if they really do mean distance (radius) from the boiler or the copper run?

  2. dobbie

    dobbie Well-Known Member

    Length of copper pipe,they must have cut it down because it was always a metre.
    I would not use plastic though and do everything in copper pipe.
  3. Dave Marques

    Dave Marques Member

    Pipe manuafacturers say follow the boiler recommendations. If they say 60 cm, they'll know best.
    sfmanus likes this.
  4. The Teach

    The Teach Well-Known Member

    Running all visible pipe in copper looks professional :)
    Heat and sfmanus like this.
  5. andy48

    andy48 Active Member

    The length of the copper run. The issue is to do with the temperature of the water, not the temperature of the boiler casing, which, with any modern boiler, will be low.
  6. pal123

    pal123 Member

    I also have a Worcester Bosch combi boiler and am about to switch the copper fittings on the flow/return with HEP20 plastic fittings at a distance of 1.25m (flow) and 1.5m (return) from the boiler. I assume this is ok?

    Also for the hot water I think this also needs a minimum of 1m?
    Can the cold water inlet be completely plastic? Or does this need to be copper 1m from the boiler?
  7. sfmanus

    sfmanus Member

    • The approach I ended up adopting was centred around making sure that if I ever needed an engineer in the future, I’d avoid any disagreements if copper was used as much as I could around the boiler. In my configuration, the shortest distance to any plastic is over 4m in run length.
  8. pal123

    pal123 Member

    Hang on sfmanus, are you saying that the legal minimum copper run length before going to plastic, at the flow/return/hot connections is 4m? Because that's not what I've read anywhere
  9. sfmanus

    sfmanus Member

    No, I said in my configuration.

    When I called WB they said 1m radius (not run length). I suggest you call their technical to check.
  10. pal123

    pal123 Member

    I called WB a few months ago, they said 1m run length.

    Also, what compression fitting do I need to connect directly to the boiler for the 15/22mm hot/cold water and flow/return to have compression fittings (no solder) throughout the pipes?
  11. sfmanus

    sfmanus Member

    I've contradicted myself - they originally said 60cm and that was the run length as confirmed earlier in the thread.

    Directly to the boiler? You mean from the outlet/inlet manifold? Absolutely no idea if so, but I'd personally get in a qualified engineer for that part.
  12. Heat

    Heat Well-Known Member

    Get a plumber like myself in to do it all and copper pipe with soldered joints for all the connections except obviously the compression joints at boiler.
    Definitely a job for tradesperson.
    Why attempt it yourself?
    sfmanus likes this.
  13. pal123

    pal123 Member

    I've got 1.2m soldered copper before going to HEP20 plastic on flow/return and hot/cold water. The overflow is completely soldered copper. HEP20 have stated that the minimum copper pipe run length, from the combustion chamber to plastic, is 0.3m. So 1.2m is plenty.

    I have put plastic HEP20 fittings in and replaced all the 1970's soldered copper in the property (which was green rusted in places) and am now looking to dry pressure test before turning the radiator flow/return back on. I've read on the HEP20 website that, as I don't have any slimline fittings, that I need to run 2 tests. Normally what pressure tests are run for HEP20? I have a basic dry test kit (toolstation

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