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faulty or undersized expansion vessel on CH could it affect poor flow issues

Discussion in 'Plumbing and Central Heating' started by Sig_star, 15 Nov 2019.

  1. Sig_star

    Sig_star

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    Hey,
    As tile,
    Could a faulty or undersized expansion vessel on CH affect poor flow issues.
    Thanks
     
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  3. Mottie

    Mottie

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    I wouldn't have thought so. If faulty on a combi or system boiler and the pressure is too high or too low, it wont work. I must add, I'm not a heating engineer though so I could be talking out of my backside!
     
  4. Sig_star

    Sig_star

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    Thanks anyone else know?
     
  5. ianmcd

    ianmcd

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    No not really what issues are you having
     
  6. Sig_star

    Sig_star

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    Hey,
    Poor flow around my CH underfloor heating system just installed.
    I have changed everything possible and now have manifold direct in to boiler to try and find out what it could be with still no or not much flow to allow the heat to be pushed around.
    Thanks
     
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  8. Sig_star

    Sig_star

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    Can I just ask a stupid question. When it was all complete with mixer/blender ect. If I turned off the flow and return to the boiler with some lock off valves before the manifold and pump in theory then creating a loop within itself I still get no flow O on the flow pots.
    How is this possible.
    It’s not air or blocked and pump is fine and on max
    Thanks
     
    Last edited: 15 Nov 2019
  9. Sig_star

    Sig_star

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    Like this picture I have attached. This should still pump water around the system. And show in my opinion the max flow I can achieve with this pump with the flow gauges opened max along with actuators. I still get no flow or hardy any where I have been told this pump is fine for the run length set on setting 2! I have also noticed the flow pots when set for the flow desired. When I get it working a little on one zone. Will just creep up every 10 mins as it heats up I guess but this is shutting off the small amount of flow I had and I have to Open it up more again but same thing will happen time over. So strange! Thanks
     

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  10. ianmcd

    ianmcd

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    definately nothing to do with the Expansion vessel,did the UFH ever work properly, is this just a recent fault ?
     
  11. CBW

    CBW

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  12. Sig_star

    Sig_star

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    Hey, I did not think it would be but mate I tried everything. I think the one in boiler is just about big enough for the volume of water in system. But not had any pressure drops or spikes. Going to put a larger vessel on it when I sorted this issue out anyway I think.
    As for it work yes and no. It’s new but we have had it working with better flow but not great and in my opinion it been deteriorated and getting worse. Hence why I been back tracking it all way to boiler to find the issue now I am putting flow piped direct to boiler nothing else in the way the lot removed it’s flow to manifold flow of pump and return back to boiler still not great flow! I need to set these flow pots to around 2/2.5 litres per minute but lucky if I can get them at 1 atm.
    Why can this system not pump within its self and loop when shut off I can not understand the most. It’s like it’s fighting its self. But everything in correct way following the flow. I don’t understand the pots how I can have them set then they change on there own 10 mins later I have to open them more again. Surly that’s not right u open it at 2 it should stay at 2 if u keep changing them u never know a correct flow down each loop no mater what the flow meter says
    Many thanks
     
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