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Discuss New Central Heating with 10mm pipe in the Central Heating Forum area at

  1. swhyte1981

    swhyte1981 New Member


    I recently purchased a cottage type bungalow and currently there is no central heating in the house only electric storage heaters.
    I am in the process of removing all the storage heaters and installing the new central heating.
    All the floors in the house are cement and all the exterior and internal walls are full of king span or glass wool insulation. Making it a real headache to get pipes to the radiators.

    My plan at the moment is to run 22mm flow and return from the boiler into the loft space to 22 x 10mm manifolds and drop feed the radiators down behind the walls and then behind skirting boards and up to the Rads. Most of the Rads will be underneath windows. All runs of 10mm pipe will be +/- 5m flow and 5m return back to the manifold. The largest radiator in the house will be 1100 x 600 double, 8 x Rads in total.

    I also plan to fit an indirect unvented cylinder in the loft space and pipe the coil in 15mm.
    Central heating boiler is a Firebird enviromax outdoor oil boiler.

    I know a lot of people don’t like to use 10mm for central heating but seems to be my only option without channelling the cement floors.

    I have recently read that a lot of new build houses central heating systems are done a similar type way. Do you guys think what I have described will work OK with the length of runs of the 10mm pipe?

    Thanks in Advance
  2. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Need to be qualified to fit the cylinder also 22mm is required

    And 15mm to the rads I would do
    • Agree Agree x 2
    • Like Like x 1
  3. Pickwickpick

    Pickwickpick Plumber

    As above, for the safety of yourself, your family & your neighbours, please get someone who is G3 qualified to fit the unvented cylinder.

    With regards to the piping, if I was in your position I would go for 15mm and channel the floor if need be. Seems a shame to go to all this effort only to stand an increased risk of blockages and issues further down the line that will be expensive & disruptive to fix.

    Also as a general rule of thumb, anything that is common practice in new builds is almost certainly not best practice.
    • Agree Agree x 1
    • Funny Funny x 1
  4. swhyte1981

    swhyte1981 New Member

    Appreciate the reply's.
    For sure I will have qualified Plumber to fit the boiler and cylinder.
    My plan to reduce cost was to rough in all the pipework and have a plumber do the final install.

    Agreed 15mm would be much better than 10mm.
    But do you think it is possible from what I described for the system to work OK if well maintained and plenty inhibitor?

  5. EvilDrPorkChop

    EvilDrPorkChop New Member

    Do a lot of systems like that and don't have any issues. 15mm is better and preferred, but not always ideal for the install.
    • Like Like x 2
    • Agree Agree x 1
  6. king of pipes

    king of pipes Trusted Plumber GSR Top Contributor!!

    It will work if executed properly alot of new builds are done that way the boiler and unvented cylinder are notifiable so will need fitted by a registered installer , any work you carry out yourself will need checking and pressure testing . Kop
    • Like Like x 1
  7. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Will have problems later as the bore is reduced to 6mm in parts like most new builds
    • Like Like x 1
    • Agree Agree x 1
    • Winner Winner x 1
  8. Rob Foster

    Rob Foster Top Contributor!!

    No matter how much you ask us Mr1981 will get the same general reply ...22mm main supply and 15mm to the rads. Plus the visual effect of microbore to the rads and anywhere seen ...immediately
    says old, amateur , skin flint
    cheap etc. if you will want to extend or sell on your plans for
    microbore are plain wrong.
    • Friendly Friendly x 1
  9. swhyte1981

    swhyte1981 New Member

    Thanks for the feedback.
    Will take onboard and may go with channeling floors for 15mm, also good to know that the 10mm systems can work.

    • Like Like x 1
  10. Allgoode

    Allgoode GSR

    Don't forget to forget to run you 15mm Hep2o or Speedfit in conduit to protect it in the floors & then have a 90 degree fitting & bring it up in 15mm copper.

    Looks a lot better than other options.

    • Like Like x 1
    • Optimistic Optimistic x 1
  11. Rob Foster

    Rob Foster Top Contributor!!

    dead right 15mm copper upstands from floor up to rad valves everytime chking
  12. king of pipes

    king of pipes Trusted Plumber GSR Top Contributor!!

    15mm plastic fittings buried in the floor or walls hmmm personally I would try and avoid this , but each to their own . Kop
    • Agree Agree x 3
    • Like Like x 1
  13. Jimmy18

    Jimmy18 New Member

    Why not just use plastic coated copper in the floor. Denso tape all the joints, will last forever.
    Make sure you make up your rads and measure from centre to centre of your valves for your first fix otherwise will look carp
    • Like Like x 4
  14. SimonG

    SimonG Trusted Plumber Top Contributor!!

    Get your plumber on board now. Will save headache later.
    • Agree Agree x 3
    • Like Like x 1
  15. Best

    Best Trusted Plumber

    Or better to have the rads screwed to walls first and pipe to them, if possible
    • Like Like x 4
    • Agree Agree x 2
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