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Discuss Can't isolate radiator in the Central Heating Forum area at

  1. Sanjay Savani

    Sanjay Savani New Member

    I have a valve on the feed/return of the radiator and i cant shut it off. The trv end shuts off but all my radiators have this (as shown in pic) on the other side which i cant isolate with to change radiator. Help please do i need to drain the whole system to remove one radiator?

  2. Riley

    Riley Plumber GSR Top Contributor!!

    Is the part in your hand a cap
  3. Sanjay Savani

    Sanjay Savani New Member

    Yes it tightens to the outside thread so that being on makes no difference just looks pretty.

  4. Riley

    Riley Plumber GSR Top Contributor!!

    Difficult to tell from the angle but is it an Allen key type slot?
  5. Sanjay Savani

    Sanjay Savani New Member

    The inside is round so not allen key. And the outer nut thing wont turn on any of the rads.
  6. Riley

    Riley Plumber GSR Top Contributor!!

    The centre of the nut is round but is there a different shape below that in the cavity
  7. Sanjay Savani

    Sanjay Savani New Member

    Not sure. It was a mates house he bought an i took that picture earlier today. I will check and see if it ia allenkey inside. I will get back to you on that one tomorrow. Thanks for the reply. Much appreciated
  8. Riley

    Riley Plumber GSR Top Contributor!!

  9. Best

    Best Trusted Plumber

    Either a slotted screw or an Allen screw below the caps. Most likely Allen screw on modern LS valves that have no exterior spindle
    • Agree Agree x 1
  10. king of pipes

    king of pipes Trusted Plumber GSR

    As above needs to be shut off with the appropriate allen key count how many turns it takes to close . cheers kop
    • Agree Agree x 1
  11. fixitflav

    fixitflav Active Member

    I have Honeywell TRVs, > 20 years old. They're provided with isolating caps. You remove the TRV head, screw on the cap and it closes the plunger. I assume that gives complete closure, like an iso valve, but it's many years since I tried it. Whether more modern ones have this feature, or whether yours does, I don't know.
    But unless you can catch the water effectively, or there's nothing it can damage, you might be better off isolating all the other rads then draining the system remotely. That way there's only a small amount of water left in the rad. Also it's easier to catch the water from a drain fitting, so if you have inhibitor in the system you can return it when the job's done.
  12. scott_d

    scott_d Plumber GSR

    Looks like a danfoss LSV
    as above use an Allen key
  13. Sanjay Savani

    Sanjay Savani New Member

    Yes it is a danfoss valve. Allen key shuts it off. Thanks all for the help. Much appreciated.
    • Like Like x 2
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