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Discuss Should UFH be nearly scalding at floor with Vinyl (LVT)? in the Underfloor Heating Forum area at

  1. Chalked

    Chalked Plumber GSR

    I would be getting them back in. You don’t just switch this stuff on. Needs commissioning properly.
    • Agree Agree x 1
  2. Gasmk1

    Gasmk1 GSR

    65 dgrees C is the input temp 53 degrees is the return temp afte rgiving heat up so its way too hot on th e flow as mentioned to you, all needs setting up properly
  3. Mr S

    Mr S New Member


    Thank you for your recent advice re the temperature of my UFH; it was invaluable.

    Hoping for a second go.

    Our plumber returned the other day and finally - so he assured us - properly commissioned the UFH. We have noticed on more than one occasion that when we try to run UFH to multiple rooms the Manifold makes a VERY loud singing noise. (I say "singing" as it's quite a high pitched hum, more like an old-school kettle boiling).

    What can be causing this and what is the best way to stop this happening? Is this related to the flow rates not being properly set (despite assurances related to this)?

    Many thanks (again), Steve.
  4. Chalked

    Chalked Plumber GSR

    Hi yes that is down to a incorrectly set up system . The noise is the mixer valove struggling to control temps when the flow rate and return temp is too high.
    Needs setting at 47 degrees and then each loop needs to have a 7 degree differce.
    I’ve also had the same noise on a faulty mixer too.

    Can you post a pic of the manifold as it is set right now?
  5. Mr S

    Mr S New Member

    Hi. Thanks for your help. Sorry - I didn't see you reply until now.

    After speaking with the manufacturer - Wunda - last week I managed to make some progress with the noise by reducing the pump speed to setting "2" (the recommended speed for 7-port manifolds).

    However. There is still some occasional noise and I suspect it's down to what you say. I also reduced the outlet temperature down to the minimum (40 deg) in order not to damage the LVT even further, so it's interesting you're suggesting 47 deg. I know the loop temperature can be reduced further by changing the flow rates, but I didn't think it was so significant.

    Any advice is very welcome. Thank you.

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    IMG_2765 (1).jpg

    IMG_2764 (1).jpg
  6. Mr S

    Mr S New Member

    Hi. Further to the above.

    I should add that we have two separate flooring types - porcelain tiles (with scree) plus LVT (overfloor with s/l compound). Unsurprisingly I'm having trouble getting the temps in the rooms with porcelain times sufficiently warm given I need to keep the temp low for the LVT.

    I'm beginning to think I need two separate manifolds, given the need for a 10 degree difference in outlet temp? I wondered if you agree?

    Many thanks again, Steve.
  7. Ric2013

    Ric2013 Plumber

    No. That's the temperature of the water from the pump, which should be a mixture of hot boiler water and cooler water that has already made a circuit of the UFH.
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