Connecting flexible tap hoses to plastic pipework

Discussion in 'Plumbers' Talk' started by Dannyj84, Jul 27, 2021.

  1. Dannyj84

    Dannyj84 New Member

    Had a disaster over the weekend when one of the pipes under the sink burst in the night, flooding the kitchen!

    I have been out and bought some new tap hoses, isolation valves etc to repair them. I have put everything in, but just wanted to check if there are any ways to safeguard against this happening? Also to confirm I have connected the taps properly.

    The pipework for the hot and cold is 15mm plastic. I have inserted a new pipe insert into the end of each, the hoses come with a nut and olive, which I have put onto the plastic pipe, inserted the pipe into the hoses, a couple of wraps of PTFE tape on the thread and then tightened the nuts up. All looks good at present, have I missed anything?

    Are there any ways to safefguard against this happening again? wrapping self amalgamating tape round the connections etc? Or is that overkill?

    Many thanks
  2. jonathanc

    jonathanc Screwfix Select

    no need for tape. use the correct insets for compression fittings and it should be fine. Do not over tighten. but i don't like compression onto plastic...

    Personally i would do one of the following:

    a) use a push fit tap hose with incorporated isolator or

    b) use push fit fitting to transition to copper then isolator & tap tail adaptor in the isolator to fit the flexi tail to
  3. Dannyj84

    Dannyj84 New Member

    Thanks, so something like this,
  4. FlyByNight

    FlyByNight Screwfix Select

    If you have to use compression, what type of olive? It must be copper not brass.
  5. jonathanc

    jonathanc Screwfix Select

  6. DIYDave.

    DIYDave. Screwfix Select

    When you say ‘a pipe burst’ -
    was this on the hot/cold poly pipe supply or one of the flexi hoses burst or possibly a fitting separated from a pipe ?

    Always buy branded, quality flexi hoses when using them as like many products, plenty of poor quality stuff out there that looks shiny and fine but it’s made to a (cheap) price

    As above, recommended to stick to same brand pipe/inserts/ fittings/ when using plastic plumbing but when adding on to what’s already there, not always easy to ID what’s in place

    And if using compression fittings with plastic, just use the plain inserts without the extra O Ring or 2 (with some brands / Super Seal)
  7. FlyByNight

    FlyByNight Screwfix Select

    It is ESSENTIAL to match the inserts and pipe - the OD is defined but ID can vary slightly. Matching pipe and fittings is good practice (and I try to keep to that) but provided you use just plain inserts there is not usually a problem.
  8. pppmacca43

    pppmacca43 Screwfix Select

    Can you take a couple of photos of under your sink, will make things a lot clearer.
  9. Dannyj84

    Dannyj84 New Member

    Here are some photos. Ignore the red square, the pipe had been connected for around 2 years so not sure what caused it to burst off. The left hand pipe burst at the connection with the flexi hose for the cold water.


    PXL_20210727_123357057.jpg PXL_20210727_123349186~2.jpg
  10. FlyByNight

    FlyByNight Screwfix Select

    Go right back to the 90 degree joints and maybe replace those too. Use plastic push fit all through including isolation valves.
  11. pppmacca43

    pppmacca43 Screwfix Select

    All that ptfe around the threads will be hampering the olives tightening rather than helping. I agree with flybynight, your best bet is probably to start again. If You use pushfit and then you will have no worries about whether anything has been tightened enough. I would use copper but as a diyer u may find pushfit easier :)

    You will need to
    1: Isolate hot and cold
    2: cut pipe above elbows
    3: put inserts into pipe and push on speedfit valves
    4: install new pushfit flexi hoses
    5: install pipe between hose and valve, using inserts again
    6: turn on water and test.

    you will need to make sure pipe cuts are square so a cheap pair of cutter may be worth buying.
    You could also do in copper, or tidy up what u have there already. I would take all the tape off, it’s not helping. Make sure it’s copper olives and retighten. As long as the correct inserts have been used and it’s tightened correctly there shouldnt be a problem.
    Dannyj84 likes this.
  12. Dannyj84

    Dannyj84 New Member

    Thanks that's really helpful. What I have repaired it with so far is just stuff I had in the shed. To get it back working again.
    pppmacca43 likes this.
  13. FlyByNight

    FlyByNight Screwfix Select

    Last edited: Jul 27, 2021
    pppmacca43 likes this.
  14. Tilt

    Tilt Screwfix Select

    If it burst then I would suspect it was not quite tightened enough in the first place....... Cannot say for sure though.
  15. Dannyj84

    Dannyj84 New Member

    Hi all, thanks for the advice. I've replaced the plastic pipework going to the tap hose tails with copper.

    But now there is a pitiful dynamic pressure at the tap when in use. Both hot and cold are truly terrible.

    I've even tried changing the pipework with isolation valve for just a straight piece of copper pipe to see if the isolation valve was restricting flow, but that didn't help!

    Could the tap have been damaged ?

    I can't think of any other reason for low pressure? I thought maybe a leak but there is no obvious leak and with it being both hot and cold, seems very unlikely they're both leaking.

  16. pppmacca43

    pppmacca43 Screwfix Select

    Have you got new flexible hoses? Maybe the bore in them is less?
    What type of tap is it, do u have a picture? You could try unscrewibg the aerator(if it has one) from the from the spout, these often get bunged up. Take it out and clean, and open tap when it’s out to see what flows like.
    Also with some taps the cartridges shave very small openings and can become blocked easily.
  17. DIYDave.

    DIYDave. Screwfix Select

    Strange one, even more so as reduced pressure on both hot and cold - and you haven’t changed the tap during these works ?

    Was going to say that perhaps the iso valve wasn’t fully opening - even though the screw looks to be in the correct orientation but again, chances of both being faulty and you’ve removed them to test and still poor

    Flexi hoses to taps kinked ?

    Blockage somewhere from loose PTFE that’s found it’s way inside pipe / flexi hose / tap /

    Flush through pipework into a bucket or connect a garden hose to a length of 15mm copper and see what comes out / can also take tap apart to visually check and blast through to clear a possible blockage
  18. Dannyj84

    Dannyj84 New Member

    I initially bought some new speedfitpushfit uPVC hoses, when the flow was rubbish I changed them back to the original ones as in the photo, but flow is still rubbish.

    Tap is a mixer tap as per the photo. Apologies about the mess. Just done the pots PXL_20210730_082542866.jpg PXL_20210730_082610595.jpg PXL_20210730_082610595.jpg
  19. pppmacca43

    pppmacca43 Screwfix Select

    My guess would be there is something blocking the cartridge.
    I would firstly take the shower head off the tap and try without that, just incase it’s that.
    As DIYDave suggested, you can disconnect the hoses then blast the coppers into a bucket to ensure u have good flow before the tap. If you have you know the issue is on the tap or flexis.

    If flow is still poor I would take the cartridge out.
    You will need to isolate water, then take the handle off. Sometimes there is a grub screw u can see, or sometimes you unscrew the lever part and there is a grub screw under there. Once the handles off there is normally a brass nut to undo, once that’s undone the cartridge pulls out. There may be some scale or debris like ptfe or a stone blocking the inlet holes in the cartridge.
    Whilst the cartridge is out I’d be tempted to turn on the valves and give it a blast through the open tap as well. Might need help for that as it’s best to hold your hand over the opening to direct the water down onto the sink.
  20. I'm no plumber by any means so forgive me if I'm wrong but if pressure at taps was fine before burst and now it's weak since replaced pipes...have you fully opened the main stop tap ?
    pppmacca43 likes this.

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