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Discuss bleeding flow and return from boiler to UFH manifold!! in the Underfloor Heating Forum area at

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  1. John2008

    John2008 New Member

    Hi, I have just installed my Underfloor heating. 4 zones in total and pressure tested after filling each loop. I have now connected up to the 22mm flow and 22mm return (new install where the plumber who installed a new boiler left these ready for me). The current system have a radiator curcuit which works fine however the UFH circuait is isolated via a manual valve on the flow and manual valve on the return. Here lies my issue, I need to purge the flow and return from each valve up to the manifold (length of pope to purge is say 20m), how do I do this? The flow should be ok by isolating each UFH loop and simply bleeding the air in the manifold, how do I bleed/purge the return?

    Any help would be fantastic!!
  2. SimonG

    SimonG Trusted Plumber Top Contributor!!

    There will be instructions with the underfloor kit. Hose pipe is normally handy as well.
  3. John2008

    John2008 New Member

    I've filled the actual ufh pipes as per instructions. I'm asking regarding the main flow and return from the boiler to the manifold as they are currently empty and isolated via valves next to boiler.
  4. Rickster123

    Rickster123 Guest

    A picture of the set up would help?
  5. Chalked

    Chalked Plumber GSR

    Have you any air vents on the manifold? If so, just turn on the valves ( leave ufh off)
    bleed air from manifold. ( make sure zone valve is manually open)
    Re pressurise.
    Turn on Any zone to make boiler circulate.( not ufh)
    Bleed again.
    Re pressurise.
    Turn on ufh.

    With that length of pipe there will still be some air, but will find its way to high points like towel rails and upper floor rads. These will need bleeding after a day or so.
    • Like Like x 1
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