Draining a hot-water cylinder (title edited)

Discussion in 'Plumbing and Central Heating' started by MarcoM, 2 Dec 2021.

  1. MarcoM

    MarcoM

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    Hello,

    I need to replace an immersion heater element and unfortunately this is at the bottom of the (cylinder). There is no draincock from the (cylinder) itself, there is a 22m feed going through the bottom so I was wondering if there is a 22mm self piercing tap that could be used to drain the tank from this feeders? Or is there any other way to empty this? Just unscrewing the element means that I have to use a small pan to empty the (cylinder) and it would take forever plus some spillage as i open up the heating element.

    Thanks
     
    Last edited by a moderator: 2 Dec 2021
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  3. BlueLoo

    BlueLoo

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    Sometimes you have a right to hate plumbers......

    Do all the disconnect/shut off stuff and drain the head off the tank using the house taps. Use a big towel and take of the vent taping of the top.
    Then, using a garden hose and a big pair of lungs, syphon the tank empty.

    Once empty, think about adding a tap to the bottom feed/return.
     
  4. MarcoM

    MarcoM

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    yes i did swear at the plumber who installed the system....

    Do you think a self piercing tap is suitable on the bottom feed?
     
  5. BlueLoo

    BlueLoo

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    Yes, for draining, but i'd put a proper tee/cock in it for the next time you need to do this anyway.
     
  6. MarcoM

    MarcoM

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    Pic of the bottom feed.
    It has been painted white, I guess I need to scrape the paint off before putting on the self piercing tap?
     

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  7. BlueLoo

    BlueLoo

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    Depends.....

    I can do a bit of plumbing, (Just) so i'd just drain it off, and add in the cock whilst i was fitting the new immersion.

    However, whilst a tap will work, it does interfere with the flow rate through the header pipe and isn't the most secure of tappings so is a risk of leaks in the future. I'd use a std compression tee. Easy enough and reasonably secure. I imagine the solder and flux addicts might not agree.....
     
  8. oldbutnotdead

    oldbutnotdead

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    Beware those self-piercing taps- the disc of copper it punches out has to go somewhere.
    I fitted one at mum's house probably 20 years ago (for a dishwasher)- sealed fine, dishwasher works, hurrah. Turned the kitchen tap on to fill the kettle up (v good mains pressure), it wouldn't turn off. Water off again, stripped kitchen tap- there it was in the tap seat, 6mm or so copper disc.
    Far better to drain as advised above then tee off the bottom tube & fit a drain valve as part of the job
     
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  9. OwainDIYer

    OwainDIYer

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    If you have a hot tap that's below the level of the cylinder, putting in two tees into the cold in (bottom) and hot out (top) and joining them with a pipe with a stoptap in means that you can open the stoptap and then drain most of the cylinder down through the hot tap. Can be handier than having to use a bucket in the airing cupboard. Close the stoptap for normal use.
     
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  11. MarcoM

    MarcoM

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    Hi again, I thought against the self piercing tap also because I would not trust the tap wrapping properly aroundthe existing feed which has had paint on it 20 plus years.

    So I will drain it from the top with a hose / syphoning. The first reply above states to open the 'vent taping of the top' .
    I am assuming this means the exit pipe at the top of the tank? There is no vent as such there.
     
  12. Exedon

    Exedon

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    Yes top connection it's a combined feed/vent
    Be careful siphoning one of my mates finished up in hospital for 3 days after a load of crap from a cylinder arrived at end of hosepipe bit quicker than expected and finished in his lungs!
     
  13. MarcoM

    MarcoM

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    I am thinking of using some sort of inline pond pump for the job to avoid the issue of having to blow the pipe
     
  14. BlueLoo

    BlueLoo

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  15. ianmcd

    ianmcd

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    just syphon it
     
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  16. oldbutnotdead

    oldbutnotdead

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    Siphon v easy when the water source is deep. Bit of hosepipe at least 3 times as long as the height of the cylinder. Push one end in to bottom of cylinder, tape something heavy to it if you have room . Push the rest of the hose into the cylinder in a coiling motion. Thumb over the end of the pipe, hold it there, pull enough hose out of the cylinder so the end with yr thumb on is below the bottom of the cylinder. Release thumb, water flows.
     
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