Underfloor heating

Discussion in 'Engineers' Talk' started by Ianeman, Feb 19, 2022.

  1. Ianeman

    Ianeman New Member

    Hi, hope someone can advise me here, I’m a Brickie by trade so be gentle I’ve had underfloor heating installed throughout the house on a self build project I’ve been doing and over the last few weeks I’ve had it running at 18 Degrees Celsius, just to help everything acclimatise but I’ve noticed parts of the floor at different parts of the house at different times will stay cold. I’ve checked at the manifold and the lower bar with the actuator controls ( wireless Heatmiser system) the pipe for the cold section of floor will be cold even though the system is asking for heat and the actuator is open. Ive tried closing all other zones apart from the cold zone and bleeding that section of pipe by connecting a hose and opening the drain off on the manifold and filling the from the boiler filter loop. But it seems to do the same after a week or so. Could this indicate I have a leak on the system or could it be trapped air? I’ve filled the boiler to 2bar (Worcester greenstar 550 cdi ) this drops to 1.5bar and holds. The manifold is showing just over 1.1 bar, slightly moves up and down depending on temperature I’ve also noticed that sometimes quite often the flow gauges with little glass tops are sticking, once you turn them slightly they drop and start working. The heating engineer who installed the boiler told me it doesn’t need inhibitor because we have no radiators, could this be why it’s sticking? Any help would be much appreciated
     
  2. Teki

    Teki Screwfix Select

    It might be easier if you used paragraphs and punctuation to split up your text.

    At the moment it's difficult to read and almost like a brain dump!

    I stopped reading after underfloor heating and Heatmiser system.
     
    E.L.M likes this.
  3. koolpc

    koolpc Super Member

    You could get a second opinion by calling in a different engineer to check the problem.
     
  4. Mike83

    Mike83 Screwfix Select

    Sounds like a balancing or flow issue or it could be a design issue.
    If all the house is underfloor then it will require a high flow rate.
     
  5. Ianeman

    Ianeman New Member

    Tell, see your point.

    thanks :)
     
  6. Ianeman

    Ianeman New Member

     
  7. Ianeman

    Ianeman New Member

    Mike 83, nothing has been balanced. The underfloor engineer did the install and pressure test and the heating engineer installed the boiler. I think as kool pc suggested, I need to get a decent engineer in.

    thanks :)
     
  8. Abbadon2001

    Abbadon2001 Screwfix Select

    You should be able to balance it by using the flow meters for each circuit - you want to broadly achieve the same flow through each, however, you may need lower flow through a room with low heat loss, or a room with carpet vs tiles, may need a slightly higher flow to compensate for lower transfer from floor to room. Assuming its all empty at the moment, are they all broadly set the same, and at a high flow rate to kick off?
     
  9. Ianeman

    Ianeman New Member

    Hi Abbadon,

    Thanks for your reply.

    Yes, the house is empty and is carpeted upstairs with engineered oak downstairs. The engineer who installed it just opened all the flow meters to full. I have noticed most of the flow meters seem to sit at about 2-2.5 until you turn them slightly then they drop to about 3 - 3.5 but the end 2 flow meters don’t move at all even when the actuator is closed or you turn them to the closed position, they just don’t move.
    This manifold has 7 actuator and there is another 2 manifolds one with 6 actuators on the middle floor and one with 5 in the attic.
    I will try setting the downstairs flow meters to about 3 and see if that helps.
    Thanks again. Oh, the pressure is just over 1 bar :)
     
  10. Abbadon2001

    Abbadon2001 Screwfix Select

    so they are all set at min flow? the ones that dont move, are they open on the return for sure?
     
  11. Ianeman

    Ianeman New Member

    The engineer told me to turn them all to anticlockwise to the max so all the flow gauges show the red float move down. I’ve since done as you suggested and closed them to between 1 and 1.5 on the flow gauge but the ones that don’t move are down passed 5 even when completely closed. This does seem to have helped. When I came in this morning, all the rooms asking for heat were working fine. I’ll try to load a pic
     
  12. Ianeman

    Ianeman New Member

  13. MGW

    MGW Screwfix Select

    Underfloor heating is slow to react, so in the main it is set to eco setting, and radiators lift it from eco setting to comfort setting, they are smaller than standard, but still need some thing that works fast, unless it is an old peoples home and heating is never turned off.

    Also the inhibitor protects where different metals are used, so if boiler has a stainless steel boiler and the pipe work is copper then you need inhibitor. I had to fit a TRV to mothers house, inhibitor used, water was crystal clear, spilt water did not mark carpet. My old house dirty brown/black i.e. the colour of iron oxide, working on the system any spill would stain carpet.

    The problem I found was the system had not been flushed fully, and so setting lock shield valves would work for a time, then muck would block them, and I would need to open fully then close again. This will happen with any restriction, since no inhibitor yet, I would flush out all valves fully open then start again, only needs a small amount of muck to mess it all up.
     
    Teki likes this.

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