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Adding isolation valves to radiator dog legs

Discussion in 'Plumbing and Central Heating' started by BloodAndBandages, 12 Dec 2020.

  1. BloodAndBandages

    BloodAndBandages

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    I've removed a radiator and eventually going to replace it with a different type of radiator, but I need to remove the previous radiator valves from the pipes and cap off the pipes with isolation valves.

    I've thought of a squeeze-off tool but don't want to damage the pipe. I've also thought of freezing the pipes, but it seems a bit tricky and it's also quite expensive to freeze two pipes.

    So my crazy idea is to have new pipe sections ready with valves fitted and I will just quickly detach the dog leg under the floor at the elbow and attach the new bit of pipe with the valve. I don't think the pressure is very high so I think it can be done quickly without too much water leaking. I'm in a bungalow and the worst that can happen is the whole lot will leak under the floor. It's happened before because a dodgy plumber forgot to put an insert in an elbow joint, so I had to repair that.

    What do you think of my cunning plan? Is it likely to work? Obviously I will turn the boiler off for a few hours beforehand.
     
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  3. terryplumb

    terryplumb

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    Crack on ,what could possibly go wrong ?
     
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  4. John the plumber

    John the plumber

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    :D:sneaky: Lol
     
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  5. Bodd

    Bodd

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    If your confident then go for it. You seem to know what your doing.
     
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  6. Madrab

    Madrab

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    o_O :confused: :eek: ..... I think that just about describes the few expressions you would have on your face once you pulled the pipe out on a sealed system but fire away ;)

    shut off the other rads to minimise water wastage and don't forget the inhibitor on the next fill up
     
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  7. BloodAndBandages

    BloodAndBandages

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    They're not called SpeedFit for nothing! I'll turn off the other rads - good tip!
     
  8. dilalio

    dilalio

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    You'll be fine.
    Release pressure from system first and vacuum allow you to work.
    One pipe at a time.
    It's what suspended floors over ground floor were made for.
     
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  9. BloodAndBandages

    BloodAndBandages

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    How do I release pressure on the system? There's a bathroom rad with an opening on the top which I used to put inhibitor in before refilling the system the last time - I could leave that one turned on and open that nut at the top... Or will that just mean water all over the bathroom?
     
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  11. Madrab

    Madrab

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    Just use a bleed point on any radiator until the gauge on the boiler reads 0 and no more water escapes. Then shut all the rads off at both valves, if your system has been balanced then mark the number of turns that each lock-shield takes to close on a postit and leave it at each valve so each valve can be reset when finished.
     
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  12. BloodAndBandages

    BloodAndBandages

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    I suspect it hasn't been balanced, although I don't think there's an issue with any rads not getting hot. The boiler is upstairs and there's only one rad up there in an open plan loft conversion. Will note how many turns to close it off anyway.
     
  13. muggles

    muggles

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    Be aware that standard ballofix-type isolation valves don't like being on heating systems. They tend to spring leaks out of the screw head after a while, especially if you try to operate them. I think it's because they're subjected to hot flowing water for extended periods, which they aren't designed for
     
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  14. Elkato531

    Elkato531

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    What boiler do you have?
    If you close the flow and return isolators on the boiler you isolate the heating system from the pressure stored in the expansion vessel and from the PRV which would allow air in and prevent the creation of the vacuum.
    Some isolation valves, however, should not be touched as they will leak afterwards.
     
  15. BloodAndBandages

    BloodAndBandages

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  16. Madrab

    Madrab

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    Nope, don't use them, they're not designed for the continued high temps in a CH system, they also aren't designed to take the chemicals that can be found in a CH too - Inhibitor/antifreeze etc.

    Normally the only valves on a CH system are either the ones on the boiler or the ones on the radiators. If you really want to use valves rather than temp stop ends then get a couple of straight 15mm rad valves, just make sure they have 15mm compression fittings at both ends and no the ones with 3/4" unions at the rad tail end.
     
  17. BloodAndBandages

    BloodAndBandages

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    Unfortunately that's all I've got and I think they will have to do the job for now. If they fail, I can replace them with speedfit couplers when there's a replacement rad in place.
     
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