Viewing 11 posts - 1 through 11 (of 11 total)
  • Plumbing question – monobloc flexi tails connection
  • peaslaker
    Free Member

    Small cloakroom basin being fitted. The tap is a monobloc mixer with 10mm threads. The plastic supply pipework is to be made up in a very tight space with it coming in underneath the shelf that the basin sits on. Isolators seem to be advised but how is this done best?

    #1: 1/2″ flex tails (that I already have) -> adaptor -> compression fit isolator

    #2: 1/2″ flex tails (that I already have) -> JG speedfit adaptor -> push fit isolator

    #3: push fit terminated flex tails -> bit of pipe -> push fit isolators

    #4: flex tails with integrated push fit isolator

    #5: ?

    Right now I’m feeling like:

    – #4 is daft. It seems neat but how do you tighten/loosen the tail in the tap when it is connected to the pipework? i.e. the isolator can never usefully isolate anything that you’re taking apart (i.e. not #4)

    – the piddly 10mm threaded connections into the tap will be overpowered by any hamfisted application of grips and adjustable and there’s too little space to get in there anyway so I am better off with the push fit options. (i.e. not #1)

    – push fit linking via adaptors to threaded fittings sealed by washers seems to be a bodge (i.e. not #2)

    So is #3 the right answer or should I just forget about this isolators nonsense and simplify even further?

    metaam
    Free Member

    I take it you have 15mm plastic pipe coming out of the wall. What size are the nuts on the end of the tails, 1/2″ or 3/8″? If 3/8″ you’ll need to use a compression fitting to convert from 15mm, it’s then a matter of having the room to fit an isolator as well. If 1/2″ you can put an isolator in and remove the nut and olive and screw the flexible hose straight onto the isolator.
    Don’t forget to use inserts in the plastic pipe.

    Blazin-saddles
    Free Member

    You can buy 90 degree isolation valves from tool station. Whack those on the end of the 15mm out of the wall, choose your 3/8 or 1/2 adapter of choice into those and then attach the flexi tails from the tap. Bob’s your mothers brother.

    https://www.toolstation.com/made4trade-900-cp-isolating-valve/p76696

    https://www.toolstation.com/tap-tail-adaptors/p14081

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    Blazin-saddles
    Free Member

    remove the nut and olive and screw the flexible hose straight onto the isolator.

    do NOT do this! ISO valves have taper fitting, tap taps are designed to seat onto flat surfaces. At the very least file down the taper, or do the job properly and use the adapters I linked.

    peaslaker
    Free Member

    @Blazin-saddles so option #1. Loading up my Toolstation basket…

    metaam
    Free Member

    “do NOT do this! ISO valves have taper fitting, tap taps are designed to seat onto flat surfaces. At the very least file down the taper, or do the job properly and use the adapters I linked.”

    I’ve been a plumber and heating engineer for 40 years and have never once had a problem doing this.

    Blazin-saddles
    Free Member

    I’ve been a plumber and heating engineer for 40 years and have never once had a problem doing this.

    Lucky you then. I’ve seen at least 5 failures due to this, most just required a new vanity unit and making good, 1 required a new kitchen ceiling after the leak brought it down. For the sake of a £2 adapter, what’s the point in risking it? I’m actually use the tails from rad valves if 1/2”.

    metaam
    Free Member

    My experience is there’s more chance of a chromed fitting blowing out of a compression joint, so lucky you then.
    To the OP. I was only trying to help, in future I’ll refrain from giving advice on forums, I obviously don’t know enough.

    peaslaker
    Free Member

    @metaam, thank you for your thoughts. I’d read about the pros and cons of fitting direct onto the threaded end of a compression fitting and I’m sure it is percentages game; theoretical risk doesn’t equal certain disaster. I have also seen these which seem to directly address the problem: https://www.amazon.co.uk/dp/B09R27L9QH/ref=cm_sw_em_r_mt_dp_77T6BD3HD2DABV08F3DV

    I also found a stash of radiator tails. Sounds like good reason not to use those too.

    This is the last part of a larger install. New bathroom, megaflo and pressurised break tank.
    I’ve had a few problems with my plumber having a hit and miss success rate on compression fittings. We’ve been going around all the joints multiple times to chase out the leaks. Doesn’t give much confidence. He seems to be using pipe sealing cord on the threads which seems all wrong to me. Overall it is a big install and sometimes I’ve found joints so loose he’s obviously lost track of which ones have been done. So right at this instant I’m not too keen on compression joints in combination with this plumber. I’ve done my own in the past and sometimes use PTFE tape on the olive which always seems to work. I do my own end feed and solder ring fittings in copper no problem and all the copper work done by the plumber has been good; the plastics have been good too. It is just the compression joints causing problems. As there are a few on plastic I may take some apart and check for the presence of inserts.

    For this last fiddly little job I just was getting to a point of despair of not being able to see how to join part A to part B without parts B, C, D and/or Z. So many ways to skin this cat and none of them particularly appealing.

    Blazin-saddles
    Free Member

    My experience is there’s more chance of a chromed fitting blowing out of a compression joint, so lucky you then.

    Really? Because I’ve not seen that happen either, so that makes us even. It wasn’t a personal attack on you, just pointing out the risks involved. If you don’t agree, that’s just your opinion, just like mine is mine. I’ll refrain from giving anymore advise also, as I clearly don’t know what I’m doing either despite making a living at doing it for the last 25 years.

    peaslaker
    Free Member

    As an OP in need of advice, thank you both. Both opinions have helped me.

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