22mm to 10mm Radiator feeds.

Discussion in 'Plumbers' Talk' started by plasterer69, Feb 19, 2014.

  1. plasterer69

    plasterer69 New Member

    Hi guys,
    I am first fixing a new central heating system in my house, I have run 22mm plastic around the ceiling void which tees down to 15mm pipe for the rads. The pipes feeding the downstairs are chased into the exterior walls but aren't ideal as they don't flex enough to make radiator connection easy. I asked a plumber to look at it and he said they shouldn't be in exterior walls due to heat loss. The ground floor is concrete floors.
    A new gas main needs to be installed, can this be buried in concrete floor?
    Can I fit 15mm to 10mm reducers to radiator feeds and run more flexible 10mm pipe to boxes behind rads?
    Any advice welcome.
  2. tom.plum

    tom.plum Screwfix Select

    Its ok to run pipes in exterior walls, I do it all the time just be sure they can move or they'll tick tick tick behind the surface and drive you nuts, also make sure any fittings can move too, or they'll bust apart through expantion, its better to NOT have reducers or any fittings in the plaster but use the cieling void for all fittings, so come from 22mm to 10mm in the ceiling void and run 10mm pipe behind the dry lining to a box behind the radiator,
    plasterer69 likes this.
  3. Sean_ork

    Sean_ork Screwfix Select

    unless the pipes are very well insulated you'll loose massive amounts of heat if the rad feeds are embedded in external walls - you want to heat the interior of your house not turn the external wall into a really bad storage heater

    have you considered dropping the rad feeds down in 10mm plastic, which has significantly less heat loss and is flexible enough to feed direct to the valve, and doesnt need any joints or adaptors from the 22mm/manifold ? - and exit the wall using the a wall outlet plate, all of the plastic pipe makers do one - very commonly used in refurbs and newbuilds

    gas feeds need to be sleeved


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  4. plasterer69

    plasterer69 New Member

    Thanks tom.plum,
    The plumber also said I would need to run copper to the rad tails where they are exposed above floor level. Is this correct?
  5. plasterer69

    plasterer69 New Member

    All the pipe work is plastic. The 22mm is already in place with 15 tees coming off. I plan to use 10mm to feed rads through a box behind rads as above.
  6. Sean_ork

    Sean_ork Screwfix Select

    can you change the 22 - 15 - 22 tees to 22 - 10 - 22 and come direct into 10mm rad valves - so 10mm all the way from the 22mm, avoiding the need to adapt down ? - probably a bit late for that
    plasterer69 likes this.
  7. plasterer69

    plasterer69 New Member

    I was hoping to use 15mm to 10mm reducers at the 22 15 22 tees?
  8. Sean_ork

    Sean_ork Screwfix Select

    same effect - just another joint and more fittings to buy - I assume you are going direct into a right angled 10mm valve at the rad ?

    like this .........

    Last edited: Feb 19, 2014
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  9. plasterer69

    plasterer69 New Member

    The valves are facing the floor direction, can I buy adaptors?
  10. Sean_ork

    Sean_ork Screwfix Select

    just use a socket elbow coming down from the valve - 10mm plastic straight in from the wall plate - that picture above shows the way - make sure you have 10mm valves

    plasterer69 likes this.
  11. plasterer69

    plasterer69 New Member

  12. DIYDave.

    DIYDave. Well-Known Member

    The plumber also said I would need to run copper to the rad tails where they are exposed above floor level. Is this correct?

    This is usually done when you would have plastic pipe on show, ie. if you were bringing pipes up from under the floor to the rad tails
    Plastic looks cheap and nasty when you can see it so would swap to copper under the floorboards, but this is purely for cosmetic reasons

    Looks like your bringing pipes down behind rads so wont be a problem in this case, in fact neater as no pipes on show
    plasterer69 likes this.

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