10mm Microbore tube capacity

Discussion in 'Plumbers' Talk' started by Wheel-nut, Feb 13, 2004.

  1. Wheel-nut

    Wheel-nut Member

    Can anybody tell me what the maximum BTU load is for 10mm microbore tube. The whole system is plumbed in 10mm tube to a single manifold which is on 22mm pipe.

    The runs to the radiators are fairly short at about 8 metres each way.


    I was going to start dear wheel-nut but it didn't sound right somehow but to your question,

    According to the quick sizing table contained in the HVCA central heating design guide 10mm pipe can carry 2500W the limiting factor being the velocity of the water in the pipes. If it exceeds 1.5m/s which is the maximum velocity specified in BS 5449 you will start to get noise problems.

    So that you have the whole picture 8mm carries 1500W, 15mm-6000W, 22mm-13000W, 28mm-22000W and 35mm-34000W. For an efficient fast acting system microbore feeds should normally be restricted to runs of no more than one metre and the system pipework reduced as the load reduces. I hope this answers your question and helps to resolve your problem.
  3. Wheel-nut

    Wheel-nut Member

    MP, many thanks for the data. I need to add a radiator which would be back to back with an existing radiator in the adjacent room. I was hoping against hope that I could tee off the pipes to that one....

    The existing radiaror at 7050 Btu is right on the limit for 10mm pipe so I will run another pair from the manifold.

    Thanks again for the data.

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