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Discuss NO I AM NOT AN UNDERFLOOR HEATING EXPERT! in the Underfloor Heating Forum area at UKPlumbersForums.co.uk.

  1. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    I am no underfloor heating expert. But would be grateful for any help. Can someone tell me why when the UFH is on and nothing else is on. The radiators get hot. And no it's not the 2 port valves. They are both cold both sides? But somehow the return pipe for the heating gets hot? I'm thinking reversed circulation but cannot see where?:mad::mad:
     
  2. SimonG

    SimonG Trusted Plumber

    Sounds like reverse circulation. Can only be that if the 2 ports are cold.
     
  3. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Any ideas where I should be looking?
     
  4. SimonG

    SimonG Trusted Plumber

    Between the underfloor return and rad return.
     
  5. Matchless.plumb

    Matchless.plumb Trusted Plumber

    Good question though, never came across this type of issue. But if You both think it's the reverse circulation then how does that work
     
  6. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    No idea mate. That's why I'm on here:p:p
     
    • Funny Funny x 1
  7. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    I can see where all 3 returns meet as all the valves and the unvented are in the loft with the boiler. How do o fix it mate?
     
  8. SimonG

    SimonG Trusted Plumber

    Easiest is to put a non return valve on the heating circuit return just before it tees back on.

    My responses are a little slow and out of sink as my posts have to be ok'd.
     
  9. deg

    deg Member

    Non return valve between the two should do the job if the returns are exposed.
     
  10. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    No worries mate. Been a naughty boy?:p
     
    • Like Like x 1
  11. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    I'll give it a go and see what happens.
     
  12. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    So I have been back and fitted the non return valves. The rads are still coming on when the UFH is on? Any more ideas?
     
  13. townfanjon

    townfanjon Trusted Plumber GSR Top Contributor!!

    Blimey weird one this , is there a pump on the heating and one on the UFH or has sombody tried to use just one ? Bypass anywhere ?
     
  14. Stigster

    Stigster Plumber

    Here is an example of a system in backflow condition. It's not the same as OP's problem exactly but it does show how it happens in this diagram.

    http://www.hertsboilers.co.uk/tech/backflow.jpg
     
    • Like Like x 1
  15. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Cheers mate. I get the concept. Just don't get why it's doing it now. When it has not for the last 6 years. The owner has not had any work done either.
     
  16. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Is it all the rads or just some ?
     
  17. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Just some mate.
     
  18. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    When the underfloor comes on does the flow or return get hot first
     
  19. Chalked

    Chalked Plumber GSR

    I would bet the underfloor return is teed into the heating return. Then teed into the main return.
    I should have a dedicated flow and return from the mains.
    And so should all other zones too
     
    • Agree Agree x 1
  20. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    Need to go back and check as it was late and left the owner to test. But have fitted non return on all returns as the are all exposed in the loft. So doubt it is the returns getting hot.
     
  21. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    Unless the rads are on the manifold it's got to be coming through the return
     
  22. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    That's is exactly what I am thinking. But I cannot see where. I will go back and check however all three returns are all on the pipework back to the boiler in the loft next to the cylinder
     
  23. Stigster

    Stigster Plumber

    That was for Matchless because he asked how reverse circulation works so I just put up a quick post to the diagram. I hope you find what's going on with your problem, it's a bit baffling for sure.
     
    • Like Like x 2
  24. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    No worries my post sounded harsh but was not meant in that was either
     
  25. GH77

    GH77 GSR Top Contributor!!

    Do you have access to Thermal imaging? . I've got a FLIR that plugs into the bottom of my phone, use it on UFH all the time, will show you where and how the heat is moving around, if you let the system all go cold then return the next day hopefully that will shed some light on the problem
     
  26. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    No, but I may have to invest in a camera? There another expense?:(
     
  27. GH77

    GH77 GSR Top Contributor!!

    Around £200, but very useful especially with UFH
     
  28. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    I'll have a look into them
     
  29. ShaunCorbs

    ShaunCorbs S. Mod Trusted Plumber GSR Top Contributor!!

    flir one
     
  30. Matchless.plumb

    Matchless.plumb Trusted Plumber

    What model of flir have your got if you don't mind me asking
     
  31. GH77

    GH77 GSR Top Contributor!!

    Flir One for ios, i've hire £4000 worth of Thermal imaging in the past and while the Flir is not at that level of imaging it's amazing value for money and definitely up to the job.. i had a job recently in a school that had 7 manifolds supplying 30 zones all with rf stats, the loops hadn't been laid to the drawings, but the stats had been associated to the drawing resulting in stats calling zones they weren't in .. I worked through the building one loop at a time tracing it's route with the Flir and marking up the manifolds, i then cleared the channels on the controllers and repaired all the stats correctly, was a long process and took 2 days, but couldn't have done it without thermal imaging and drastically cheaper than buying/ hiring a £4k camera :)
     
    • Like Like x 1
  32. Matchless.plumb

    Matchless.plumb Trusted Plumber

    Thanks a lot for your reply is much appreciated. Do you remember what model it was ? Must have been a massive help and a relief for you
     
  33. Harvest Fields

    Harvest Fields Trusted Plumber GSR Top Contributor!!

    The model is a Flir one for iOS. Type it into google mate. It will come up. I have just done the same. Just over £200.00
     
    • Like Like x 1
  34. Matchless.plumb

    Matchless.plumb Trusted Plumber

    Thanks harvest!!!
     
  35. Matchless.plumb

    Matchless.plumb Trusted Plumber

    Is not a bad price if you need to use a flir camera. Does this model do the job if so that's not bad, I guess quite a good investment
     
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