How does a push button toilet flush work?

Discussion in 'Plumbers' Talk' started by WillyEckerslike, May 12, 2018.

  1. WillyEckerslike

    WillyEckerslike Well-Known Member

    Stupid question time but it won't be my first - or last.

    I've fitted dozens of them and replaced conventional syphons with them but I'm unsure exactly how they work. Even taking one apart hasn't really helped.

    A syphon I understand - and how the principles of short and long flush work. I understand that a push button has a seal which is lifted to release stored water but why doesn't it close again immediately on releasing the button and furthermore, how do long and short flush differ?

    It's just one of many things that puzzle me.
     
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  2. KIAB

    KIAB Well-Known Member

    Last edited: May 12, 2018
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  3. Devil's Advocate

    Devil's Advocate Well-Known Member

    Good Q, Willy. And the answer is - I dunno.

    I imagine it's a system where there's a flap which is lifted open when you press the butt, and the cistern water then rushing out is effectively aimed 'upwards' at that flap thereby keeping it open, until a point is reached where the water flow has diminished enough to allow the flap to close under gravity.

    But there is every possibility that I'm wrong - unlike with Brexit.
     
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  4. WillyEckerslike

    WillyEckerslike Well-Known Member

    Thanks KIAB. Although the video is good, it doesn't show me how it works - just how to install and adjust one. It will be something simple as they're generally reliable.
     
  5. WillyEckerslike

    WillyEckerslike Well-Known Member

    Thanks DA. I think you're right about using the water somehow which is why I think I couldn't make much headway with the unit I took apart as it was out of the cistern and dry.

    There is no doubt a YouTube video explaining it somewhere - I just haven't found it yet and I thought that one of my forum colleagues might know anyway.
     
  6. DIYDave.

    DIYDave. Well-Known Member


    Third push button type is ‘air button’ or pneumatic

    Dunno how they work but no cable or rods ...... just air to activate
     
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  7. Crowsfoot

    Crowsfoot Well-Known Member

    Basically Wills, it's just a plunger that lifts on the push of a button just long enough to let the water out of the cistern to flush the toilet pan, nothing scientific at all about it (unlike the syphon)!

    On holiday in Spain I came across a lever connected to the WC which appeared to be connected to the mains supply. You simply lift the lever just long enough for the mains pressure to flush away the contents of the pan.
    "Whoosh" (and it was all gone)!

    I keep telling people that after Brexit we'll all have to go back to the tradition "British bog" complete with a high level pull chain :):);)!
     
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  8. KIAB

    KIAB Well-Known Member

    Burlington cisterns, those were the days:),still like them.
     
  9. WillyEckerslike

    WillyEckerslike Well-Known Member

    Would that still be the case for the long flush? Whilst not disagreeing with you, it has made me wonder if there's some trapped air and/or floats involved which lower the plunger as the water level drops? That would maybe slow it down for the long flush.
     
  10. WillyEckerslike

    WillyEckerslike Well-Known Member

    I've just had another look at a Geberit unit I've got in the workshop. Pushing either button lifts the plunger the same fixed amount in both cases and it returns down at the same speed as well. The short flush button just lifts the plunger whilst the long flush also lifts some additional gubbins inside the unit and operates an additional lever near the bottom. Crowsfoot is right but there's a little more to it I think.

    What has surprised me is that I've not been hit by a barrage of answers. It could be a low volume of traffic on the forum or, like me, a lot of us just fit these things without understanding what's going on...
     
  11. candoabitofmoststuff

    candoabitofmoststuff Active Member

    I'm just the same!
    I think you'll find, like many things, that this is one of those instances where it's simply "magic" and there is no other explanation!

    Regards,
    Cando
     
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  12. Crowsfoot

    Crowsfoot Well-Known Member

    I'd always assumed that the long flush raises the plunger further up than the short flush one does (got me thinking now).
    Not all cisterns are dual flush though.
    I'll have to have a look at one at work tomorrow.
     
  13. Crowsfoot

    Crowsfoot Well-Known Member

    After extensive tests in the back of my van I can conclude that inside the push button are two small rods one longer than the other. A small flush extends both the rods to make contact with the device that lifts the plunger up the shaft a set distance. However, on a long flush the longer rod extends a little further (around 5mm) and pushes the device (a cable on my test) that lifts the plunger up the shaft an extra (5mm) which is enough height for a longer flush.
    All interesting stuff eh.
    Thanks goes to Wills for bringing an easily overlooked item to the mine and the forums attention.
     
  14. facilities

    facilities Well-Known Member


    Got me thinking about Thomas Crapper & his syphonic flush invention about 150 years ago, I don’t see how his invention has been improved on really, and in some cases a step back ?

    Wonder what other inventions which are still used and not improved on over hundreds or even thousands of years, perhaps the engineers vice, blacksmiths Anvil, the wheel (did say thousands) water Level,
     

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