Shower trap problem

Discussion in 'Plumbers' Talk' started by Jamesk51, Apr 6, 2016.

  1. Jamesk51

    Jamesk51 New Member

    Hi guys,

    Have a problem with a shower trap not draining away correctly. It's in a new house and has only been up and running about 2 weeks. The problem is that after 2-3 minutes the water builds up in the tray and overflows into the floor because the water isn't draining away quick enough.

    Then whenever you take the shower trap out and let the water drain away and replace the trap the water drains away fine for 20+min with no issues. Then whenever you leave the shower untouched for 1-2 hours and come back and run the shower the water builds up again and overflows due to the water not draining away quickly enough.

    Can't figure this one out and have tried this process about 5 times now with the exact same results each time.

    There is a toilet and wash hand basin in the room as well that are joined into the same 100mm sewer which then runs outside.

    The only thing I can think of is that the toilet or basin is interfering with the shower waste trap and causing it to airlock or create some sort of syphonage whenever the shower has drained. Then whenever you remove the trap after it reblocking it lets this air away and then works fine.

    Has anyone any ideas what the problem could be and how to fix it?

    Thanks
     
  2. KIAB

    KIAB Super Member

    When shower tray is full, does flushing toilet affect it, is there any effluent smell after flushing toilet, or when running shower,or basin.

    Is there a stack pipe which ventilate in the loft, or through the roof.
     
    Last edited: Apr 6, 2016
  3. Jamesk51

    Jamesk51 New Member

    No flushing the toilet doesn't seem to have any effect on the water level or any smell.

    Yes the soil stack is vented from outside the building.
     
  4. KIAB

    KIAB Super Member

    I can't see it being a airlock,is there sufficent fall on shower waste pipe.
    You haven't got any flexi pipe in shower pipe run, hopefully it's rigid 40mm pipe

    Might pay to rod pipe, could have some crud dropped or washed downed, which obstructing pipe,some tilers, etc can be dirty sods.
     
    Last edited: Apr 6, 2016
  5. Jamesk51

    Jamesk51 New Member

    No there's no flex pipe it's all solid 37mm pipe.

    I didn't fit it so i'm not 100% sure about the fall but it was fitted by a guy who has done my work for over 10 years so he knows what he's at.

    I don't understand why it works fine when i take the trap out and then put it straight back in but then after being left for 1-2 hours it blocks itself again.

    Something seems to happen whenever it's finished draining and is left alone over a hour.
     
  6. KIAB

    KIAB Super Member

    Think you should get your guy back to have a look at it, difficult to think of anything else without actually see the pipe & it's layout myself.
     
  7. DIYDave.

    DIYDave. Screwfix Select

    What kind of shower set up are you running
    Massive amounts of water via a 3 bar pump and rain head shower

    Can produce a large litres per min and some traps can struggle to drain quick enough
    Some traps are designed to deal with a larger volume of waste

    As you said, recently fitted by ur guy and and have used him for over ten years so should be no problem getting him back
     
  8. KIAB

    KIAB Super Member

    Been giving this paragraph some thought, & I'm stumped:oops:, as to the 1-2 hour,water build up & not draining away quickly.
    I point the blame to the fall on the pipe as being too shallow,(18mm per mtr minimum), but you could try a wire snake or use a plunger & rodding from shower to stack pipe, just to sure it's clear.

    If there is sufficent fall, then water should ok.
     
    tore81 likes this.
  9. Jamesk51

    Jamesk51 New Member

    lol you and me both. It's doing my head in. Iv'e done it about 10 times now take the trap out and put it back in and the water runs away perfect for at least 10min. It would probably run all day but I haven't tried any longer than 10 min. Then turn the shower off, go away for a hour, come back and turn the shower on and the water straight away just begins to build up and not drain away.

    I'm going to try fitting a anti syphon trap on the toilet and basin tomorrow as I think they must be effecting the shower trap some how. They are easily changed unlike the shower waste which is under the floor and tiled! :mad:
     
  10. KIAB

    KIAB Super Member

    How long is the pipe run from shower to stack, does it feed seperately into stack.

    You will draw air in though basin overflow, & stack vent, you have no smells, so I can't see negative pressure being the problem.

    Can alway result to drastic measures, cut out ceiling below to get access, I have done that many times over the years, just to save riping up a tiled floor:eek:, easier to replace a bit of plasterboard & cheaper.:)

    Your plumber install plumbing, so he should sort it out.
     
  11. Glad its Friday

    Glad its Friday Active Member

    Guess it must be hydraulically locking somehow, maybe the waste pipe initially falls and then goes uphill a bit. Think it is going to have to be opened up to check unfortunately.
    Also agree with KIAB, could well be grout washed away down there that has got stuck.
     
  12. Neil1987

    Neil1987 Member

    I've seen a problem similar to what you describe I eventually worked out that the problem was a mistake between the run and the trap , the internal tray was the style that was like a full cup with rectangular notches cut out round the top. I solved it by enlarging the depth of the rectangular cut outs but gotta watch you don't cut to much out and get smells coming back up
     
  13. Dave does Gas

    Dave does Gas Screwfix Select

    If its a new house as you state get the builders back to sort it, the more you fiddle the easier it is for them to reject the job as you were the last one to touch it.
     
  14. Phil edge

    Phil edge New Member

    Hi. I have had exactly the same problem. Pipes clear and once you clear the airlock with a plunger of something it is fine till next time.
    Simple solution I found.
    Wedge a piece of wood between the outflow pipe and the tray to increase the slope of the first 300-400mm of the drainpipe by a few degrees. Don't worry about the rest of the pipe. This will alter the speed of the water as it starts down the pipe and hey presto - no air lock
    Worked for me. Good luck.
     
  15. koolpc

    koolpc Super Member

    Nice thread revival! :p
     
  16. The Teach

    The Teach Screwfix Select

    The date in the small print is small :D but the subject will be mentioned here again soon,very low profile shower trays and uk plumbing techniques do not always agree.
     
  17. koolpc

    koolpc Super Member

    We have a low profile shower. I hate how it drains slow too! Thing is, as we are selling, due to divorce, I don't give a monkeys now!
     

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