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Discuss Ufh problems temp control and radiators temp in the Underfloor Heating Forum area at UKPlumbersForums.co.uk.

  1. Pkitch

    Pkitch New Member

    Hi guys
    Our recently installed UFH system is causing us trouble and we are struggling to get the fitter to help, problem one is we have to slowly build up the heat as the new floor is tiled but the only way to do this is by turning the boiler heating controls down as low as it goes, 30 degrees, if we have it set to 60 the temp on the flow is 45 degrees which is the maximum we can run at.
    The mixing valve is fully set as low as it will go so effectively we can’t run the UFH at any other temperature than maximum 45 degrees when boiler is set to 60.
    The other problem is when the UFH is running the radiators through the rest of the house struggle to get to temperature!
    System is a Wunda with a Wilo pump, please help?
     
  2. chris watkins

    chris watkins Plumber

    So what help do you require ?
    What commissioning advice have you received regarding heating the thermal mass.
     
  3. Pkitch

    Pkitch New Member

    We can’t run radiators effectively at the same time as the UFH and the UFH won’t run cooler than maximum which is a problem when your floor is freshly tiled.
     
  4. chris watkins

    chris watkins Plumber

    Yes I know and understand but there isn't a solution apart from additional heaters in the areas that are cold.
    I say again what were you expecting, did they not explain the commissioning process?
     
  5. SimonG

    SimonG Trusted Plumber

    Put some pics up. Sounds like an installation issue.
     
  6. Pkitch

    Pkitch New Member

    Yes we commissioned the ufh when screed was dry, then left it off for tiling then left it to dry for a further 3 weeks before we gradually raise the temperature, problem I have is in this cold weather the radiators won’t heat up because the boiler has had to be set to minimum temperature, from what I’m led to believe I should be able to leave the boiler set to 60 and use the mixer valve to reduce the ufh temperature but I can’t do this and would like to know why?
     
  7. Pkitch

    Pkitch New Member

    I’ll get some pictures up when I get home
     
    • Like Like x 1
  8. chris watkins

    chris watkins Plumber

    So the mixing / blending valve isn't working then?
    You should be able to set the boiler stat at say 70 & the mixer to give a circulating temp around the U/F of 50 degC.
     
  9. Pkitch

    Pkitch New Member

  10. Pkitch

    Pkitch New Member

    Here you can see the inlet flow temp is about 25 degrees but I can only achieve this by turning the central heating on the boiler to minimum
     
  11. Pkitch

    Pkitch New Member

    Chris that is my guess but the system is new and the blender/mixer valve does operate but not as low as it should do
     
  12. Craig Watson

    Craig Watson Plumber GSR

    Have you been specifically told to run your underfloor at 30°? Screed should be left to dry for about 30 days before any tiling. If you waited the correct time before tiling and now waited a further 3 weeks, you will be fine to run your underfloor in the lowest setting of the blending valve and gradually increase it over the next few weeks.
     
  13. Pkitch

    Pkitch New Member

    All commissioning has been done to the letter, my problem is I can’t run my ufh at any lower than maximum temperature which I should be able to without turning my boiler ch control down to minimum as this affects my radiators in the rest of the house, you should never turn on ufh systems to full temperature from the offset as this can crack screed and tiles, it must be raised and lowered gradually
     
  14. chris watkins

    chris watkins Plumber

    What is the design temperature for the U/F heating ?
    It is normally 50deg C water to give a floor surface temp of around 29 why do you think your should have lower temps ?
     
  15. Pkitch

    Pkitch New Member

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