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New shower trap not draining well.

Discussion in 'Plumbing and Central Heating' started by hexdex, 30 Aug 2017.

  1. hexdex

    hexdex

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    Ok, so with a bit more experimenting I'm left even more puzzled. So I unscrew and remove the mushroom cap and then replace the tube and seal so the water is not restricted by the cap to see what happens. So the water drains down directly into the trap but still fills up the tray and so the tube sitting in the trap fills, the water goes over the top of the trap level but won't 'waterfall' over the inner tube and drain away as it should. If i then lift the insert the water happily flows directly down the drain bypassing the trap. But it refuses to operate properly via the water trap. If after getting the water to flow i then put it back together it will work ok....for a while. I am left thinking that for whatever reason, it's just not suitable.

    So all I can ask is for any replacement traps that anyone can recommend?
     
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  3. It looks as though the water is going through the cap, and then down the central tube before spilling over the inner section, into the outer well. If I'm right, then raising the mushroom cap won't achieve anything. You almost need a small inner tube, to allow more water to flow through it. The last one I used like this was even worse, so unfortunately, I can't help you any further, but you need to look for a high flow trap, or as I said, put the cap on after you've used the shower.
     
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  4. hexdex

    hexdex

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    Yep, I guess that's it. Bloody stupid design. I expected better from McAlpine. It's supposed to shift 26ltr per minute. Lucky if I get 1

    Thanks for your advice.
     
    Last edited: 1 Sep 2017
  5. mcmoby69

    mcmoby69

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    Remove the o ring and try it.
     
  6. The O ring should be providing the seal to stop smells.
     
  7. Jackrae

    Jackrae

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    Since you are enquiring about changing the trap I presume you can get under-floor access. If that is the case, remove the existing trapand fit a simple 90mm connector (with no integral trap); then, in the drain line, a short distance away from this item, install a simple U trap. Because you are using a full bore "U" and it is 'seeing' a greater head of water/suds than the shower tray version was, it'll pass much, much more flow.
     
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  8. hexdex

    hexdex

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    Thanks Jackrae. I can gain access, but it won't be easy. Rather than pulling up the newly laid tiles I'll have to approach it from the room next door which is only about 2 feet away from the trap. Though the clearance under the floor boards will be around 18" and under a beam! But it's do-able. I'll just wait a few weeks until the next house project moves me into that room and I'll be pulling up the carpets anyway. At least I have another option now.
     
  9. If it's on the first floor, would it be easier getting at it from under the ceiling. 2ft's a bit of a stretch.
     
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  11. dilalio

    dilalio

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    Before going to all that trouble, first try cutting the dip tube so it's shorter but still in the water trap and see if that improves things!
     
  12. dpsservices

    dpsservices

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    Can you not remove the hair trap the bit that's in the middle and with mushroom on try that for now. Had this problem couple of times and found removing the hair trap helps improves
    Regards david
     
  13. Hot&Cold

    Hot&Cold

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    How long is the total drain run to your soil pipe and how many bends,tees are in this run.

    There is one known brand of shower gel which creates ton's of lather burst (foam).

    That measurement is correct under test conditions with out excessive lather (maybe just water only) and with correct waste pipe installation,remember it needs a head of water sitting in the shower tray to create a good flow rate through the trap.

    How much water is sitting in the shower tray ? Does it all drain out eventually ?.
    Its assumed the shower tray is level and the waste trap is in an area which collects water first.is your shower tray square,quadrant or rectangular ?
    edit,have you got a flexi waste pipe on your shower trap ?

    Have used this type of mcalpine shower trap fitting on a slow drainer before and it worked.
    trap 90mm.jpg
     
    Last edited: 2 Sep 2017
  14. tony7

    tony7

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    Hi, I just new in here :)

    I got my shower installed about a month ago and it wasn't long till I discovered the trap, McALPINE ST90CP10-70 couldn't cope with water coming from the shower.
    I contacted Mcalpine but they weren't helpful at all, and said, the trap has a flow rate of approx-34 L/min.
    (I have a Aqualisa - Quartz Digital Thermostatic Shower)
    What I have discovered is, when the cup part is in the trap on its own without the inner tube fitted, the water drains away no problem and if I "set" the inner tube section into the cup that's already in the trap the water also drains away without bother.
    I did think of cutting about 3/8" off the inner tube to see if that would help.

    It was then I did a google search and found this site :) and seen the post about.. shower trap not draining well.. I decided to cut 3/8" off the inner tube and try that, well I did and then fitted/snapped it in place to the cup part and pushed all into the trap while the shower was running but no,the water started to fill the shower tray again so the cup and inner tube had to be remover ASAP.

    As I said before, when the inner tube is sitting on top of the cup part of the trap, the water runs free, so I'm thinking, is it air tight somewhere?

    Any thoughts.

    Thanks in advance.
     
  15. Jackrae

    Jackrae

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    One other possibility is that your drain line has a dip in it somewhere which creates a second 'unintentional trap'. Two traps in series greatly reduces flow rates. Assuming the shower drains into the same system as your toilet, one way of finding out if there is an unintentional trap is to remove the inner tube from the shower trap and then flush the toilet. With your ear to the shower trap, if you hear the toilet draining then there is a clear run from the shower to the drain. If you cannot hear the toilet drain then there is a possibility of an unintentional trap being created somewhere in the shower drain line; in which case you might want to consider doing away with the shower trap's inner tube.
     
  16. tony7

    tony7

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    Thanks Jackrae, well, its the same drain line that was there for the shower that was install before this new one and there was no problem before.
    That's a good tip btw, thanks. I was thinking, if a few holes were drilled or wee slots made in the right place it would come good.
     
  17. Jackrae

    Jackrae

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    If you drill or cut above the static water level then the trap serves no purpose (to prevent foul fumes coming back)
     
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