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Green Building Bible, Fourth Edition
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    • CommentAuthorbardo
    • CommentTimeJan 6th 2020 edited
     
    Plumbing advice please. Building a home with suspended timber floor. 300mm Ijoists at ground level with sheeps wool insulation. Wondering whether to use copper or plastic pipes for radiators/hot water and where to locate them in the ground foor. Within the joists inbetween the insulation? OR Underfloor - in which case how best to lag and avoid mouse issues? There's a 400mm void below the ijoists. Plastic is flexible making it easy to bend and go through holes made in ijoist OSB webbing however can I rely on it not to leak? If I use copper I wonder if this is flexible to bend a little and push through slightly larger holes in the ijoist webbing?
    •  
      CommentAuthordjh
    • CommentTimeJan 7th 2020
     
    Plastic is less likely to leak than copper since there will be fewer joints in inaccessible places. It should be pressure tested before being hidden away. You could always run it inside a larger diameter pipe if you're particularly concerned (like electrical cable in conduit). I would run it in the insulation, since you'd need to insulate it otherwise.
    • CommentAuthorbardo
    • CommentTimeJan 7th 2020
     
    Thank you DJH.


    Posted By: djhPlastic is less likely to leak than copper since there will be fewer joints in inaccessible places. It should be pressure tested before being hidden away. You could always run it inside a larger diameter pipe if you're particularly concerned (like electrical cable in conduit). I would run it in the insulation, since you'd need to insulate it otherwise.
  1.  
    Just consider mice. They are very fond of the plastic knuckles on the joints, which can and has lead to disastrous consequences. Whatever you use, keep it as far in to thermal envelope as poss. Try hard to avoid running wet services in the cold void under the floor.
  2.  
    Posted By: GreenPaddyJust consider mice. They are very fond of

    all things organic - along with other bugs etc. I would be a bit nervous about putting sheeps wool as insulation between joists.

    Re pipe work - have you considered alpex pipe?
  3.  
    If the pipes run parallel to the direction of the joists, it's convenient to run them between the joists, within the insulation layer but not too deep, so the residual heat losses end up in the room. I used pipe insulation as well as burying them in the wool insulation layer, as I felt the wool didn't "wrap around" the pipe very well.

    But for pipes going perpendicular to the joists, I think it is easier to go underneath the joists, rather than thread through holes in the joists.

    You can get metal pushfit fittings, which fit both copper and pastic pipe.

    Mice just love to shred the standard clip-on polyethylene foam pipe insulation, must make for comfy nesting. I'm using some foil-covered rockwool pipe insulation in the hope that it's not so comfortable.
    • CommentAuthorphiledge
    • CommentTimeJan 8th 2020
     
    If this is a new build you can drill pipe holes in the joists before installation and thread copper pipe through the holes as the joists are going in. No need to do any jointing or insulating until your at the plumbing stage, but the pipes are already fitted in any areas they need to run at 90 degrees to the joists.
    • CommentAuthorbardo
    • CommentTimeJan 9th 2020
     
    Hi Will, did you install in ijoists? What type of wool insulation?

    Posted By: WillInAberdeenIf the pipes run parallel to the direction of the joists, it's convenient to run them between the joists, within the insulation layer but not too deep, so the residual heat losses end up in the room. I used pipe insulation as well as burying them in the wool insulation layer, as I felt the wool didn't "wrap around" the pipe very well.

    But for pipes going perpendicular to the joists, I think it is easier to go underneath the joists, rather than thread through holes in the joists.

    You can get metal pushfit fittings, which fit both copper and pastic pipe.

    Mice just love to shred the standard clip-on polyethylene foam pipe insulation, must make for comfy nesting. I'm using some foil-covered rockwool pipe insulation in the hope that it's not so comfortable.
    • CommentAuthorbardo
    • CommentTimeJan 9th 2020
     
    Hi Peter, I'm pretty confident mice and bugs won't get in to the insulation. I put a lot of work in to the detailing. The alpex pip sounds interesting. Have you used it? What are the merits?

    Regards
    Stefan

    Posted By: Peter_in_Hungary
    Posted By: GreenPaddyJust consider mice. They are very fond of

    all things organic - along with other bugs etc. I would be a bit nervous about putting sheeps wool as insulation between joists.

    Re pipe work - have you considered alpex pipe?
    •  
      CommentAuthordjh
    • CommentTimeJan 9th 2020
     
    As well as security from animals and insects, the other thing to be mindful of in floor insulation is drainage, particularly with organic insulation. Drainage and insect protection sometimes seem incompatible! :)
  4.  
    Posted By: bardoThe alpex pip sounds interesting. Have you used it? What are the merits?

    I have used alpex, I found it good, the 5 layer alpex has an O2 barrier, useful on closed systems. It is reasonably easy to install and can be got pre-insulated. The joints are either swaged (install all the pipework then hire the machine for a day) or bolt-up. The fittings tend to be more expensive than copper but you use a lot less of them and with a bit of planning you can avoid fittings in hidden places (like underfloor). Alpex pipe is good for drinking water as well as CH.

    I have also installed a CH system using 6mm nylon microbore - very easy but benefits from a centrally placed boiler as each radiator had its dedicated supply and return from the manifolds. Although microbore seems to have gone out of fashion these days.

    There are a couple of threads on here about using sheeps wool insulation under floor - probably worth a read if you haven't already done so.
    • CommentAuthorbardo
    • CommentTimeJan 10th 2020
     
    Thanks Peter. I will revisit the sheepswool threads.

    Posted By: Peter_in_Hungary
    Posted By: bardoThe alpex pip sounds interesting. Have you used it? What are the merits?

    I have used alpex, I found it good, the 5 layer alpex has an O2 barrier, useful on closed systems. It is reasonably easy to install and can be got pre-insulated. The joints are either swaged (install all the pipework then hire the machine for a day) or bolt-up. The fittings tend to be more expensive than copper but you use a lot less of them and with a bit of planning you can avoid fittings in hidden places (like underfloor). Alpex pipe is good for drinking water as well as CH.

    I have also installed a CH system using 6mm nylon microbore - very easy but benefits from a centrally placed boiler as each radiator had its dedicated supply and return from the manifolds. Although microbore seems to have gone out of fashion these days.

    There are a couple of threads on here about using sheeps wool insulation under floor - probably worth a read if you haven't already done so.
    • CommentAuthorrevor
    • CommentTimeJan 11th 2020
     
    I would avoid any joints that eventually become inaccessible. Could be trouble in years to come. A lot will depend on your finished floor covering and whether you will in the future be able to lift it and gain access. Are you already committed to I joists? I used web based joists "posi joist" and they are just great to run pipes through.

    I used plastic pipe under floor and connected to copper with brass compression fittings elsewhere for domestic supply. (Also had to comply with my insurance company as I had to agree to no hot work so no soldering and the crimping gear was too expensive) Compression joints are a great benefit if later you want to modify the plumbing.

    Given the void under the joists I presume this will be ventilated to avoid damp issues in which case pipes will need to be well insulated.

    I used alpex for underfloor heating and I would consider this for conventional CH system. It is easy to bend and retains the shape so you are not fighting it like you would do with barrier pipe. It also comes in very long coils mine were 360 m long so less wasteful. If you use it there are different diameters around the 15 mm size mine was 16 mm and if you want to connect up to 15 mm you will need conversion fittings. So be aware.

    If you are planning on soil pipe or ducting to go under the floor they may need to go in when you fit the joists.

    Have not used sheep's wool insulation but I looked at it and considered it to be too expensive. Also been horror stories about it getting moth eaten if it's not been manufactured properly.
    •  
      CommentAuthordjh
    • CommentTimeJan 11th 2020
     
    Posted By: revorI would avoid any joints that eventually become inaccessible.

    That's actually quite difficult to arrange in most cases. It's bad enough in electrical wiring, where the wires are extremely flexible, but can become insuperable with plumbing where even flexible pipes have quite large minimum bend radius.
    • CommentAuthorbxman
    • CommentTimeJan 13th 2020
     
    A naive question perhaps

    If it is a new build would the money not be better spent on more or better insulation .

    Should there be a need for central heating these days ?
  5.  
    Posted By: bxmanIf it is a new build would the money not be better spent on more or better insulation .

    Following this question is there an advantage to a suspended floor over an insulated slab?

    Posted By: bxmanShould there be a need for central heating these days ?

    That is a leap of faith for many people - architects and SEs included (or even more so!)
    • CommentAuthorbardo
    • CommentTimeJan 13th 2020
     
    Re Alpex, the plumber I am working with is concerned about fittings. 15mm is standard. And we need to fit to radiators.

    We have decided to lay the pipes in the already installed ijoists so that we don't expose pipes into the 400mm ventilated void.

    The pipes will be sandwiched within Thermafleece Cosywool insulation which I've used in other projects and had not problem with insects. There was an issue way back before they changed the treatment though that was sorted many years ago. After posing on this forum and considering the inorganic options I am sticking with the sheepswool.

    Given that the pipes will need to run along the spine of the sleeper wall building in the centre of the building it also means I will need to drill a hole through the centre of the OSB webbing.

    I am interested in alpex however can't see the real merit over plastic especially given that we will need to adapt to fit onto copper pipes coming out the floor and into small radiators.

    So my main concern is to ensure the pipe fittings are the best possible, the system is carefully pressure tested and that I have some way to remove floor boards if needs be.

    Before building I explored the possibility of a slab, underfloor heating MVHR. I chose a suspended timber floor with a wood burner (we grow our own woodfuel here) with backboiler / solar system, trickle vents. I appreciate that's not everyone's cuppa here.













    Posted By: revorI would avoid any joints that eventually become inaccessible. Could be trouble in years to come. A lot will depend on your finished floor covering and whether you will in the future be able to lift it and gain access. Are you already committed to I joists? I used web based joists "posi joist" and they are just great to run pipes through.

    I used plastic pipe under floor and connected to copper with brass compression fittings elsewhere for domestic supply. (Also had to comply with my insurance company as I had to agree to no hot work so no soldering and the crimping gear was too expensive) Compression joints are a great benefit if later you want to modify the plumbing.

    Given the void under the joists I presume this will be ventilated to avoid damp issues in which case pipes will need to be well insulated.

    I used alpex for underfloor heating and I would consider this for conventional CH system. It is easy to bend and retains the shape so you are not fighting it like you would do with barrier pipe. It also comes in very long coils mine were 360 m long so less wasteful. If you use it there are different diameters around the 15 mm size mine was 16 mm and if you want to connect up to 15 mm you will need conversion fittings. So be aware.

    If you are planning on soil pipe or ducting to go under the floor they may need to go in when you fit the joists.

    Have not used sheep's wool insulation but I looked at it and considered it to be too expensive. Also been horror stories about it getting moth eaten if it's not been manufactured properly.
  6.  
    Posted By: bardoI am interested in alpex however can't see the real merit over plastic especially given that we will need to adapt to fit onto copper pipes coming out the floor and into small radiators.

    The alpex installation I did had the alpex pipe coming out of the floor and going straight to the radiators without conversion to copper. If the rad. is the normal height from the floor there are no problems, long(ish) horizontal runs in alpex can develop a sag over time and would be more vulnerable to knocks

    I see you are using a plumber rather than DIY. IMO there is a lot of merit in going with what ever is in the middle of your plumbers comfort zone. If what your plumber is happy using is too far away from what you want - then better to get a different plumber!
    • CommentAuthorbardo
    • CommentTimeJan 13th 2020
     
    Hi Peter,

    Good points made – what is your experience in obtaining fittings for Alpex and or converting to 15mm? I'm working with a recently retired plumber who is ok with me doing some of the work and who isn't pushing me in any one direction. I value his experience too. My reason for posting here is that it seems to be a community of people interested in more eco and non standard ways of doing things. Because I've chosen to build a home using more natural and sustainable materials I want to make sure I'm as informed as possible before making crucial choices.

    Stefan



    Posted By: Peter_in_Hungary
    Posted By: bardoI am interested in alpex however can't see the real merit over plastic especially given that we will need to adapt to fit onto copper pipes coming out the floor and into small radiators.

    The alpex installation I did had the alpex pipe coming out of the floor and going straight to the radiators without conversion to copper. If the rad. is the normal height from the floor there are no problems, long(ish) horizontal runs in alpex can develop a sag over time and would be more vulnerable to knocks

    I see you are using a plumber rather than DIY. IMO there is a lot of merit in going with what ever is in the middle of your plumbers comfort zone. If what your plumber is happy using is too far away from what you want - then better to get a different plumber!
  7.  
    Can I ask how you are holding the insulation up between the joists please?
  8.  
    Posted By: bardowhat is your experience in obtaining fittings for Alpex and or converting to 15mm?

    No problem - I just go to the shop and pick them off the shelf, same with the pipe, either bare or pre-insulated. But remember I am in Hungary and even so I live next to a small(ish) town of 16,000 population and have a choice of 3 shops selling the parts. I can't imagine that there is a problem getting the fittings in the UK e.g. Amazon UK list the items just for one example including radiator fittings to connect alpex directly to the rads.
    • CommentAuthorbardo
    • CommentTimeJan 14th 2020
     
    Posted By: ealingbadgerCan I ask how you are holding the insulation up between the joists please?


    When doing from the inside, the recommended way is to staple bands of non sticky tape to the inside of the front flanges running across the ijoists. The wool which comes at the rafter centre width is rolled out, layed out snug against the sides and has something to sit on. The edges can also be stapled to the OSB webbing or timber sides.
    • CommentAuthorbardo
    • CommentTimeJan 14th 2020
     
    Posted By: Peter_in_Hungary
    Posted By: bardowhat is your experience in obtaining fittings for Alpex and or converting to 15mm?

    No problem - I just go to the shop and pick them off the shelf, same with the pipe, either bare or pre-insulated. But remember I am in Hungary and even so I live next to a small(ish) town of 16,000 population and have a choice of 3 shops selling the parts. I can't imagine that there is a problem getting the fittings in the UK e.g. Amazon UK list the items just for one example including radiator fittings to connect alpex directly to the rads.


    That's my concern. Easily obtaining parts. I'll stick to a product I can buy them locally. Thanks
    • CommentAuthorgoodevans
    • CommentTimeJan 15th 2020
     
    I went for 16mm Pex-Al-Pex pipes for the water supply and UFH - comes in wras approved and UFH price brackets.

    I have 3 manifolds in the service room, hot water, cold softened water and un-softened water - each port has a valve on it for easy isolation.

    I ran individual pipes from the manifold to all the points in the house (sink, loos, showers, outside taps) - it seems extravagant but the installation speed was good, it is simple and no joints, and I think the pipe is half the price of copper and It can carried it in the car. To convert to copper at the far end use any compression fitting that you require, take off and discard one of the nuts and associated olive and replace with a 16mm adaptor see picture (sometimes its easier to buy a 16 to 15mm straight compression coupler and discard all but the 16mm adapter). Available on Amazon, Ebay and UFH multilayer pipe specialists.



    I prefer the versions with the 'cut olive' (as in the picture)as because these can be dismantled and reused.
      802020080.jpg
    • CommentAuthorgoodevans
    • CommentTimeJan 15th 2020
     
    And a picture of the 3 manifolds.
      Honeyview_IMAG0937.jpg
    • CommentAuthorbardo
    • CommentTimeJan 15th 2020
     
    Posted By: goodevansconsequences. Whatever you use, keep it as far in to thermal envelope as poss. Try hard to avoid running wet


    This looks a really interesting solution for the hot water system. Thanks for sharing. Re cold water I wonder about PEX for drinking water and the possibility of aluminium leaching. Did you look into this at all?

    How much space does the manifold system take up. I'm wondering if it's something I could include in the house and build a cupboard round it.
  9.  
    Posted By: bardoThis looks a really interesting solution for the hot water system. Thanks for sharing. Re cold water I wonder about PEX for drinking water and the possibility of aluminium leaching. Did you look into this at all?

    No problem with aluminium leaching as the ali. is not on the inside. The layers are (in to out) Pe, adhesive, aluminium, adhesive, Pe.
    • CommentAuthorgoodevans
    • CommentTimeJan 15th 2020
     
    Aluminium shouldn't ever come into contact with the water, and I'm not aware (nor did I look into) any issues with PEX or other plastic for cold water supply, nor for that matter brass, copper, flux and solder.

    The plumber was not keen on the idea of plastic pipes - but after this job he admitted, reluctantly, that he would do the same for his house.

    Unlike other well known pipe systems these pipes are malleable. You can bend them with a 100mm radius without kinking by hand, probably tighter by either an external spring or a internal silicon rod. When bent they stay put, have reasonable stiffness and can be "bent straight" for tidy installs.

    The manifold above is the 1 inch version - it is also available in a 3/4 inch version which I should have used given the rest of the plumbing is 22mm. the smaller manifold has the pipes spaced at 36mm centrers as opposed to 50mm that is shown in the photo. 4 port and 3 port manifolds can be linked together in a line or above each other or a combination. The plastic clips came supplied in two depths/offset to aid stacking one above the other.

    I was able to lay all the ground floor pipes in the insulation under the slab without the help of a profesional! (the insulation was 3 layers of 75mm eps with H&C above the bottom layer and the heat pump feed/return above the second layer - all under slab pipes in conduit to give a small chance of replacement in the future and the pipe channels cut with a "U" shaped hot knife. Below is a photo of the pipes coming out of the ground slab with enough length to get to the future 1st floor manifold, and in the background some of the pipes coming out where sinks are located as well as the UFH manifold.
      Honeyview_IMAG0632.jpg
    • CommentAuthorbardo
    • CommentTime3 days ago
     
    Posted By: goodevansAluminium shouldn't ever come into contact with the water, and I'm not aware (nor did I look into) any issues with PEX or other plastic for cold water supply, nor for that matter brass, copper, flux and solder.

    The plumber was not keen on the idea of plastic pipes - but after this job he admitted, reluctantly, that he would do the same for his house.

    Unlike other well known pipe systems these pipes are malleable. You can bend them with a 100mm radius without kinking by hand, probably tighter by either an external spring or a internal silicon rod. When bent they stay put, have reasonable stiffness and can be "bent straight" for tidy installs.

    The manifold above is the 1 inch version - it is also available in a 3/4 inch version which I should have used given the rest of the plumbing is 22mm. the smaller manifold has the pipes spaced at 36mm centrers as opposed to 50mm that is shown in the photo. 4 port and 3 port manifolds can be linked together in a line or above each other or a combination. The plastic clips came supplied in two depths/offset to aid stacking one above the other.

    I was able to lay all the ground floor pipes in the insulation under the slab without the help of a profesional! (the insulation was 3 layers of 75mm eps with H&C above the bottom layer and the heat pump feed/return above the second layer - all under slab pipes in conduit to give a small chance of replacement in the future and the pipe channels cut with a "U" shaped hot knife. Below is a photo of the pipes coming out of the ground slab with enough length to get to the future 1st floor manifold, and in the background some of the pipes coming out where sinks are located as well as the UFH manifold.
      Honeyview_IMAG0632.jpghttp:///newforum/extensions/InlineImages/image.php?AttachmentID=7492" >



    Thanks goodevans! Really helpful
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