Running pipework within a concrete floor?

Discussion in 'Plumbers' Talk' started by joedesign, Oct 16, 2003.

  1. joedesign

    joedesign New Member

    I am currently adding a new radiator to an extended room. When the room was doubled in size, a concrete slab floor was laid in the extension, and the builders omitted to put extra heating in to accommodate for the larger room size. I plan to angle grind a slot for 2 15mm copper pipes and I plan to bend the angles out of the slab and then refloat over the pipe.

    The question is does this pipe need insulating or any foil putting under to prevent heat loss through the ground? Also can anyone recommend a depth to sink the pipe without the concrete above cracking? This will be limited by the depth of the dampproof membrane below the slab.
     
  2. Dr Who

    Dr Who New Member

    In my home, circa 1950's, the gas pipe is run in a channel in the concrete which has been covered with sand then concreted over. I don't know what the modern day standard is.

    In terms of insulation, the foil is only good at reflecting heat, conductive heat is your main problem. I would personally fit normal pipe insulation to the pipe then concrete over (an experienced plumber may have a more professional idea)

    I would have thought that you would also need to consider the risk freezing aswell as losing heat in the ground!

    regards

    Dr Who

    (Who is a timelord, not a plumber! Though I know the Daleks who are good for unblocking sinks and toilets using their arms!)
     
  3. Dave34

    Dave34 New Member

    Current water regs require you to use "pipe in pipe". Don't think screwfix do this but www.bes.ltd.uk do. They are expensive so I was thinking there would be no harm in using some plastic pipe within some overflow pipe...?

    Dave
     
  4. Jack

    Jack New Member

    Concrete in direct contact with copper would corrode it.

    15mm copper pipes will need to move as they expand / contract with the heat produced.

    Think about using plastic push fit pipes instead... Run them in a plastic waste pipe. This means you can pull them back out (if the need arose) without breaking up the floor again.

    Couldn't you just fit a larger radiator in the existing position ?
     
  5. joedesign

    joedesign New Member

    Thanks for all the advice. I like the idea of the pipe in plastic waste pipe. I do see the logic of getting at the pipework if the need arose.

    Installing a larger rad isn't really an option in this case, as the present one is already a fairly large double and we need to provide heat for a 14 by 30 foot room. The rad is located on an internal wall and behind the best seating in the room. It is also opposite an open fireplace which causes a cross room draw.

    We already suffer from hot necks as we try to pump heat into the room, while the other half of the room remains stubbornly cold. The new position is below a large window on an outside wall in the extension. It should fix the problem of balancing the heat flow within the room.

    Thanks again for the help. Much appreciated.
     
  6. WOLF

    WOLF New Member

    the pipes must be wrapped in "DENZO" tape to prevent corrosion, then encased in sand, prior to rescreedind.
     
  7. JIM BOB

    JIM BOB New Member

    To meet water byelaws you need to sleeve it or duct it. The best way is by cutting the chase as deep as your screed and using batten and 3/4 inch ply as a cover. Do not use denzo it is only compatable with oil because the pipes heat up it affects the screeds.
     
  8. supersparky

    supersparky New Member

    dont you wrap copper pipes in that horse hair type sleve? ive seen this done alot on sites recently,
    and they are always at the concrete level just covered with screed
    hope it helps
     
  9. ALLACON

    ALLACON New Member

    see my comments to Little ERN re. copper pipes in concrete floors/screed
     
  10. benjilloyd

    benjilloyd New Member

    Does anyone know where I can buy Denzo tape, I've been trying to find it for 'years' ... Screwfix was my last hope, they don't appear to stock it.
     
  11. Mick90

    Mick90 New Member

    Have heard Denso tape isn't available anymore?? Anyway any copper pipe in a concrete floor should be sleeved to prevent corrosion. Ive always used the felt "horsehair" type sleeving.
     
  12. mj

    mj Guest

    PVC coated 15mm & 22mm is avaliable from plumbers merchants. Just cut back pvc coating where you need to make joints & then tape over exposed pipe/joints before filling channels
     
  13. Ron

    Ron New Member

    Travis & Perkins stock Denso tape i purchased some last month
     
  14. punchline

    punchline New Member

    Screwfix do sell denso tape now i noticed the other day. called waterproofing tape for roofing. sticky stuff but useful!
     
  15. I think this issue has been dealt with by now. I assume your carpet is laid too. Anyway I recall Dave34 had it right. Bear in mind Water by-laws etc. Use plastic piping over copper prior to screading.
     
  16. Freedom

    Freedom Member

    Denso is a brand name, its available as amalgamating petroleum protection tape.
    Building regs state pipes need to be covered prior to burying in walls or screed and then plumbers assume Denso will work but it won't because the heat melts it.
    Building regs are unclear and useless other than to deliberately scupper smaller traders in favour of those with shares held my MPs.
    Horse hair type sleeving is a cheap option and only works if the pipes are hot when the cement is drying so that a sleeve & gap is created.
    Pipe in pipe is a fair idea but plastic pipes are not up to the task for CH if a bolier goes out of control momentarily above 90.
    boxing is the only totally safe option for buried pipes. I always encase in 3mm steel to the front when there is a chance of DIY nails & screws entering.
    Its all humbug, complain to your MOP that the facism which created in reality worthless building regs is wrecking your small business.
     

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