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General: Plumbing with 32mm MDPE?

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    We're going to need a good flow of mains water as building control says we need a sprinkler. If the flow is enough, we can avoid 1 tonne of water storage in the attic and a pump. The incoming supply is 32mm MDPE and provides just about enough. Is there any reason why 32mm MDPE can't also be used internally?
    • CommentAuthortony
    • CommentTimeMay 29th 2017
     
    I would say yes as it would melt in a fire and then the sprinklers wouldn't work so non compliant.
    •  
      CommentAuthordjh
    • CommentTimeMay 29th 2017
     
    Are you in Wales? Or is my memory failing? What Tony says sounds sensible but water regs are not sensible IMHO, so you'll need to check.
    • CommentAuthortony
    • CommentTimeMay 29th 2017
     
    This is more about fire sprinkler system and building regs than water regs that do allow plastic water pipes indoors.
    • CommentAuthorDarylP
    • CommentTimeMay 29th 2017
     
    CoP,
    You are building in Wales...? beware, get BC to approve in writing your proposal before spending any money.
    You will not get the water co. to underwrite your sprinkler pressure, unless things have changed in the last 3 months?
    An external tank might be the best solution for you?
    Good luck :-)
    •  
      CommentAuthordjh
    • CommentTimeMay 29th 2017
     
    Posted By: tonyThis is more about fire sprinkler system

    and IIRC it's Wales that cares about them?
  7.  
    @djh, no not in Wales!

    @tony, good point about the heat. I ran it by the sprinkler installer who says it is not a problem if the pipe is boxed in.
  8.  
    I've also read somewhere that MDPE is not stable in light, but again, if it's boxed in, that shouldn't be a problem.
    • CommentAuthorDarylP
    • CommentTimeMay 31st 2017
     
    @CoP, come on then, if you are not building in Wales, why do need/want a sprinkler system?
    :bigsmile:
  10.  
    It's what building control want to comply with the fire regulations. We have an open plan downstairs and open staircase.
    • CommentAuthorDarylP
    • CommentTimeMay 31st 2017
     
    oh... fair enough...over 3 storeys? :cool:
  12.  
    Have you established that *no other means* than a sprinkler system would make it comply?
  13.  
    I ended up with a fire curtain which definitely wasn't cheap. A bit less messy to test every six months though....
    • CommentAuthorskyewright
    • CommentTimeMay 31st 2017
     
    Posted By: richardelliotI ended up with a fire curtain which definitely wasn't cheap. A bit less messy to test every six months though....

    And no issue with guaranteed water pressure (which someone mentioned earlier)...
    • CommentAuthorrevor
    • CommentTimeJun 2nd 2017
     
    How many bar are you getting at point of entry into the house? If you look at your water bill you will see a size code usually near the meter serial number. This size is what determines the rate you pay for the water. I guess this will be smaller than 32 mm if it is 32 you will be paying a lot for your water. I renewed my incoming supply some 90 M from my boundary in 32 mm replacing an old iron pipe but the leg from the 100 mm mains in the road to my meter is 15 mm the pressure drop over this short distance is minimal. Because the incoming to the meter is 15 mm I pay the cheapest rate possible for the water. You may think you have a 32 mm incoming but is it that from the meter and what is it to the meter? i.e is it the same all the way or is there a join to a smaller dia pipe in the supply. Where is your meter located? A decent water pressure for domestic use should be around 3.5 bar that is what I get in a rural area, but in a built up area because of demand you may get a lot less. I do not know what you need for a sprinkler system though. There may be mileage in seeing if it is possible to take the 32 mm back to the meter if it is not already. I would run the internal pipe in 35 mm copper the pressure drop will be quite a bit less than in a 32 mm MDPE so give you a bit more leeway. If you need extra pressure can you put a pump in the mains supply to boost the flow when the sprinkler is activated. I guess there must be a better option than having a tonne of water in the loft. Can't say I would welcome that.
  16.  
    Thanks @revor

    It's 32mm from the mains, through the meter (in the road), all the way to the stopcock on our house. The road had to be dug up for the electricity, so I asked the water co to change from a 25mm supply to a 32mm supply at the same time. I wasn't aware that I'd pay more for water according to the pipe diameter! Is this the case even if the water is metered?

    We're getting 4 bar pressure at the entry to the house, and 110 litres/min supply.

    I wasn't aware that there would be less of a pressure drop with copper than MDPE. This is a good idea.
    • CommentAuthorMike1
    • CommentTimeJun 4th 2017 edited
     
    Posted By: ComeOnPilgrimI wasn't aware that I'd pay more for water according to the pipe diameter! Is this the case even if the water is metered?

    It certainly was a few years back when I put in my main. So I've now got 32mm pipe with a 25mm water meter...
    • CommentAuthorrevor
    • CommentTimeJun 4th 2017
     
    That is a good pressure at 4 bar. did you find a pipe diameter on your bill. It may vary off course from area to area. The pressure drop benefit is that cu pipe wall is thinner so bore is bigger.
    • CommentAuthortony
    • CommentTimeJun 4th 2017
     
    With 4 bar I can't see why you need a bigger pipe, the flow is huge
    • CommentAuthorrevor
    • CommentTimeJun 4th 2017 edited
     
    Forgot to mention I pay to Welsh Water (non profit organisation) £1.31 per cu M and service charge of 8.6 p per day. My annual bill is about £120. When I lived in south Manchester some 9 yrs ago my bill was about £700 but included sewage charge and based on rateable value. I have my septic tank emptied once every 5 yrs or so and costs £80 so am quid's in being off grid for sewage. What do others pay for water? we have a smallholding and collect roof water for irrigation of our crops. We had thought of a water recovery system for the house but it would not have been cost effective no matter how green it would have been.
    • CommentAuthorgyrogear
    • CommentTimeJun 9th 2017
     
    Posted By: revorWhat do others pay for water?


    FWIW, in Brittany, for 2016 we consumed 116 m3 in 2016, net price 222 Euros.

    Sewage charge was 275 Euros

    With taxes and service charges, the bill came to 577 Euros.

    gg

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