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Radiators hot upstairs, cold downstairs

Discussion in 'Plumbing and Central Heating' started by Vin73UK, 23 Oct 2021.

  1. Vin73UK

    Vin73UK

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    Hello there, just signed up to this site and forum.

    Would appreciate any advice or ideas on what to try next, as I'm out of ideas right now.

    Issue is my radiators are hot upstairs (piping hot) and all but one downstairs are cold. The hot one is the downstairs toilet which is directly below the airing cupboard where the hot water tank is and the 3 way valve.
    It's a system, with an open tank in loft, sealed tank in the airing cupboard, boiler in kitchen with the pump directly above the boiler. Boiler and airing cupboard opposite sides of the house on different floors.
    The downstairs rad pipes drop down from ceiling height in the walls. Micro bore / 8mm pipe to the rads.

    Towards the end of last winter, I noticed the downstairs rads weren't heating so well. But were warm. Upstairs was fine.

    I've recently replaced all the radiators, except two that were almost new and I flushed those out.

    I noticed the 3 way Honeywell valve did not appear to be working or doing anything and zero resistance on the lever. I've today changed the head of the 3 way valve. It now looks to be working correctly.


    Few obeservations;

    - When the head was off the 3 way ball valve itself, the valve moved freely with my fingers, not stiff.
    - The old head, miraculously got its spring resistance back once removed, which the new head had out the box.
    - The pipes for the heating in/out the 3 way valve, are piping hot.
    - The pipes either side of the pump are piping hot, suggesting hot water is flowing through, but not sure at what pressure.
    - Boiler pressure goes from about 1.2-1.5 bar idle to about 3 bar when on.
    - Upstairs rads get hot with the heating on.
    - Downstairs, only the toliet rad is hot as before, though at least one pipe each side of each radiator is getting hot, but not as hot as the working rads upstairs. This itself is a change and advance on the original problem, as the pipes were remaining cold pre changing the 3way valve head.
    - The downstairs rads are still not heating up as a result.


    The pump is definitely vibrating when on, with piping hot water both sides, in and out. Hot water is working fine. Boiler is working fine. I've went to bleed all the rads, there was no air in any, so that wasnt a problem.


    The lockshield valves are all open, either side of each rad.


    I'm a bit stuck and confused on this now. Unless it is the pump and its just vibrating and not pumping. I don't get why the upstairs rads work perfectly fine and downstairs (all but one) don't.


    When I changed the rads, was a bit of muck in them, but all the valves and water flowing through the pipes was clear.
    When I filled the new rads by opening the valves, they filled quickly, water pressure was good. So I dont think there is a blockage.

    Any ideas or other suggestions would be appreciated.

    Cheers...
     
    Last edited: 23 Oct 2021
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  3. ianmcd

    ianmcd

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    you have an expansion problem, which must be addressed, but that is not what is causing the rads to no circulate, shut down all the working rads and see if the other then come on, and come back and let us know what happens
     
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  4. JohnD

    JohnD

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    because the radiators need balancing.

    It's curious to read that you have an F&E system but a pressurised boiler.
     
  5. Vin73UK

    Vin73UK

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    Hi JohnD, I thought it was called F&E from diagrams, but perhaps not. I've updated how its laid out above.

    Agree it could be balancing but i'd still expect all the radiators to have some degree of heat in them if unbalanced.
     
  6. Vin73UK

    Vin73UK

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    Will try this to see what the result is.
     
  7. JohnD

    JohnD

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    nope.
     
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  9. Vin73UK

    Vin73UK

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    Ok, so I shut off all the upstairs and got varying amounts of heat into downstairs. I closed up all the valves and worked from what I think is closest to furthest, with the furthest away most open, closest least open. I've got warm to hot radiators downstairs, not properly hot like upstairs was. Living rad however, not getting hot. Nor is the pipes to it.

    I've reopened the upstairs ones, with the same approach. Now they are all warm to hot, not hot hot.

    But there is circulation around the system now of warm to hot water at least. But not at optimal levels.
     
  10. ianmcd

    ianmcd

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    Post pics of what you have instead of changing the origional post
     
  11. terryplumb

    terryplumb

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    Does the downstairs rad that won't heat have a TRV ? If it does check the pin in the valve body is moving freely up an down. Then close every radiator ( using its TRV or wheel head ,not their lockshield) except the one that didn't heat and see if it now heats fully.
     
  12. Vin73UK

    Vin73UK

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    No TRV valves at all.
     
  13. terryplumb

    terryplumb

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    Ok ,rules that out. Close all rads by their wheel head ,see if cold rad heats.
     
  14. Vin73UK

    Vin73UK

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    Thanks. Will try that tomorrow.
     
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