Underfloor heating

Discussion in 'Plumbers' Talk' started by h'andy, Mar 7, 2017.

  1. h'andy

    h'andy Member

    To set the scene...I have a gravity fed oil fired rayburn and a log burner with backboiler in an old but well insulated property. The hot water system takes the primary heat through convection and the heating system pump only kicks in to move heat into the rads when either the tank has reached temperature or the feed pipes are above a set temp. The only thermostats on the system are those on the rads and on the feed pipework. It is not conventional but it works!

    I am rebuilding a small extension and wonderd whether it would be possible to fit UFH here (in place of an existing rad in that room), with a mixer to ensure the heat is not excessive (the log burner can get the temperature quite high), but with no circulation pump as I have no way of controlling it - the room cannot call for heat if the system doesn't have any! I am not after quick heat up/cool down - the house heats over a few days at the start of the colder weather and I'm happy for a slow responding system.

    Will it work?

  2. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    You will need to take a flow and return supply off the primary's from the boiler through a zone valve,

    You will then need to pump the primary's so your have to either make the system sealed or create a close coupled system to stop pump over etc

    Then you can add the uf manifold with pump, blender etc

    The system will need a new wiring centre to accommodate the new switch lives etc
  3. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Anything is achievable

    You just need to design everything so it's mechanically and electrically safe

    I can do it for you but it's not a free service as its a full system design

    There's many avenues but it's easy to do
  4. kiaora

    kiaora Guest

    if you install an u/f loop and a pumped manifold, and then the switched supply that currently fires the radiator pump on,

    can send the hot water to the u/f zone first, and then via a return stat from the u/f zone allow the water via a zone valve, round the radiators.

    so its giving priority to the u/f
    hope that makes sense?

    btw, thats free
  5. h'andy

    h'andy Member

    Thanks Guys, Kiaora's advice sounds like it might work...
  6. G&W Plumbing & Heating

    G&W Plumbing & Heating Active Member

    Yeah sure it does
  7. suzan loius

    suzan loius New Member

    Yes Agree with Kiaora.. this might have happened to underneath your floor - Plumber San Jose
  8. chippie244

    chippie244 Super Member

    It's a bit pointless spamming on here, this is a British forum. :):)
  9. george porge

    george porge New Member

    que ?
  10. george porge

    george porge New Member

    no hard feelings ?
  11. george porge

    george porge New Member

    If the rad in question that is to be replaced by UFH in the same room has a TRV on it, then this TRV is controlling the temperature into the rad. So oust the rad and run pipework underfloor in loops and connect back up to the original pipes feeding the original rad Via a Thermostatic manifold . No need for zone valves or extra wiring. Just keep the system crude as it already is.
  12. kiaora

    kiaora Guest

    The underfloor heating temperature needs to be say 50 c.and pumped,
    So if the pump is running, the trv will not control the water temperature only the room temperature.
    Also it will heat the other radiators?
    Just an observation, but perhaps I'm confused ?

  13. george porge

    george porge New Member

    just keep the system crude as it already is. The existing pump kicks in when its ready so will continue to do so and pump the water around the underfloor loop as well as the rads in its own crude way, just keep the system balanced as much as it can be. No heroics here. System works as well as h'andy is happy with and will continue to do so.
    No point confusing the issue and trying to upgrade. My personal opinion I would rip the whole lot out and start again. But if there are other factors at play here ie money, time or happy with a slow responding system etc
    Then keep it simple. The one port thermostatic manifold is sufficient enough control for the UFH loop it will work just as good as the existing TRV on the existing rad that is to be replaced. The end result is, heating water will be
    circulating round the underfloor loop and that is the aim. as regarding the specified temperatures, Put crudely
    what's the complaint.

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