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Discuss Ufh problems temp control and radiators temp in the Underfloor Heating Forum area at

  1. Pkitch

    Pkitch New Member

    Thanks Craig finally someone gets my problem lol
  2. Craig Watson

    Craig Watson Plumber GSR Top Contributor!!

  3. chris watkins

    chris watkins Plumber

    I am still at a loss what are you saying that the mixing valve is not capable of controlling the water temp in the U/F circuits as 45-50dec C when the boiler thermostat is set to provide 70 degC ?
    It is the surface temp of the tiles finish which is more important than the mean water temp, as from your posted you can see the water temp can be higher although I personally would limit it to 60. Who selected the rads ? what delta T was used ? ie. what is the design system operating mean water temperature?
  4. Pkitch

    Pkitch New Member

    Chris you are asking questions that im not sure I can answer, I’m by no means an expert on ufh but my tiles cost an awful lot so I know not to thermal shock them, I can’t find another way of explaining the issue other than what I have already posted, tiled screeded floor maximum temp is 45 degrees at manifold, when ufh is switched on you must progress to this temp gradually, I can’t do this without setting my boiler to minimum which in turn knocks out my radiators, the blending valve should allow me to do this but I can’t?
  5. bogrodder

    bogrodder Plumber GSR

    Blending valves and the associated thermometers attached are never accurate, I know this from lots of testing with calibrated equipment. They can be far out as much as 10 degrees. Get somebody decent in to check things over.
  6. Pkitch

    Pkitch New Member

    Thank you for another angle on this bogrodder, I have purchased a temperature sensor gun to test the temperature gauges and tile temperature so will get a better idea once it arrives
  7. Pkitch

    Pkitch New Member

    ok so my heat sensor arrived and it seems pretty accurate, the gauges on the manifold are reading true and with 30 degrees on the flow side I’m getting a tile surface temperature of between 21 and 22 degrees.
    My boiler is set to minimum so radiators don’t work and the blending valve is set fully to minimum so it’s not possible to run my radiators at this point?
  8. markfxy

    markfxy Plumber

    cant you turn the boiler temp up and turn the flow rate down to lower the temperature to each circuit
  9. Pkitch

    Pkitch New Member

    I’m not sure on how well that would work but thanks for the idea, we have managed to get the UFH guy back and he has agreed it looks like the blending/ mixing valve that’s at fault, I’ll update when the new valve is fitted!
  10. Pkitch

    Pkitch New Member

    Well had the blending/mixing valve replaced and it looks like it had solved the problem, thanks for everyone’s help
    • Like Like x 1
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