TOILET FLUSH SIPHON UNITS – Repair diaphragm – Plumbing Tips
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TOILET FLUSH SIPHON UNITS – Repair diaphragm – Plumbing Tips

December 3, 2019

– [Announcer],
honest reviews and advice. – Hold tight and welcome to today’s video. Today we’re going to look into
the world of syphon units, we’ve done a load of videos before on how you actually take one
of these out and replace it. But we’ve never done a video
on actually how they work. So we’re gonna cover that now, but also we’re gonna cover
the repair that you can do to these syphon units, to make them work. And also we’re gonna show you, using this lovely clear box here and a bucket just down
there how they work. ‘Cause we’re gonna sit
it inside this box here and get it running. So I hope you enjoy the video, please remember to subscribe
by clicking on the links in the corner or whatever. You can follow us on Twitter
and Facebook and let’s go! Hold tight. So number one, the components
you’ll get when you buy one of these syphon units. Firstly you’ve got a compression nut and a rubber O ring here, that you can put your flush pipe into, if you’ve got a flush pipe down. That’s for a cistern that
we call a wall hung cistern, that’s not exactly close
coupled to the toilet. So basically you can put
your pipe up into there, this will go round and
as you tighten that up, the rubber compression washer here will compress round onto that pipe and basically make a watertight seal. We’ll look at the other way
of sealing one of the cisterns onto a toilet in a second. The other piece you have, is
your actual locking nut, okay. What this does is creates compression on the bottom of the toilet cistern which is gonna be in here, onto this rubber little flange just here. So what’s that gonna do
when that tightens up, it’s gonna make that really tight and then no water will be put into our makeup system for now. Will be able to leak
through when you’re not flushing the toilet. Before I actually pop
this onto our little box that we’ve got here, it’s a great idea to know
how to get one of these out. So let’s firstly cover
the problems you can get with one of these. Let’s say you’ve got a
handle on your toilet flush, and you just keep having
to pump it to get it going. The problem with that is, and it’s really, really easy to solve, is that the flap inside here. If you look when pull
this up we’ve got a flap that pulls up like that. I mean, it’s so hard if I put it here you can actually see it
pushes air out onto my hair. What’s that doing is
initiating the syphon. You’ve probably got about
a litres worth of water sitting above this flap
and when you pull this up, this retaining plastic area here doesn’t allow that water to
escape back into the system. It’s only got one place to go. So it’ll fly up here and then down here. This downward action of
water flowing through here, acts as kind of a valve and
it carries on sucking water. That is the basic principle of a syphon. But how do you ask, does
the rest of the water come out and through? Well if you look here, these
flaps can lift up like so and basically allow all that water to carry on going through the syphon and then going out down the loo and flushing whatever
you’ve put in the loo away. That’s the great thing about them, they go back automatically because underneath
you’ve got a spring here, and that is basically the main
fault that can go with these, is this flap starts to break and that is always indicative by the fact you have to keep pumping. In the end it does sometimes work. In the end they’re just
so broken up and ruined that you can’t get at them to do it. So we’ve done a video on
how you remove a syphon unit and they’re really easy to do. A lot of them now are
even easier than that, and I have a little yellow pin in here that you can pull out and you can actually just lift top off without even having to
drain down the cistern. It’s a majorly good idea, that is. But anyway, say you’ve
got your syphon unit out, this will be handle linkage here, so as you pull your handle,
that will lift the lever up and lift this piece up here like so. What you wanna do is take
this linkage out like that and then you’ll be able to pull out the bottom part of our
syphon just like so. Remember you’ve got a couple
of washers here in the top, that you don’t want to lose. So look, now you can see, when we pull on that lever,
that’s lifting up like so and push all that water up there but then obviously once
the water starts to flow, it can go down like
that, but it can’t escape when you’re actually trying
to start your syphon. As you can see, these
are really, really easy to take these little flaps off. They’ve got two little pins
here, just pop them out, you can buy a replacement
flaps for these anywhere. I’ve even know people get
random bits of plastic like DPM or whatever,
cut it to the right size and lay it in there
and even that’s worked. Right. There we go, ready to go. So what we’re gonna do to show
you these actually work is, I’ve just got to get my drill set up. And we’re going to drill
a hole in this box here. Right so there, now
we’ve got our hole there, we’ve got our rubber flap on here, so we’re gonna push that
down onto here like so. And nip this up. I’ll just show the you
the other way these go on, usually when you’re nipping these up, you pop this little clamp on here, if you’ve got a close
coupled toilet cistern. So now we’ve got this tightened up, usually you’d have two
screws here that go down into the toilet cistern that you can see from underneath
the cistern just like this. And then to make a watertight seal on a close coupled cistern, you have a rubber doughnut like this, that goes around that cistern there okay. So we’re just gonna tighten
this up as best we can. Right so, I’ve got my bucket
here with some water in it. I’ll just pour this in. So there we go, we’ve now got a lovely
nice full toilet cistern. We’ve got a little handle here, so say your handles on
there and you pull that this is gonna lift this
flap up, just like we said, it’s gonna force water out through here and then down through this pipe for as long as it can draw a syphon for. Which will probably be until about here. Because in a minute, I’m gonna
show you that there’s ways you can adjust how much
these actually flush to save yourself a little bit of water. So, let’s just say we pull that now. Brilliant, so as you can see, we’ve got a nice full flush here. We’ve still got a little bit
of water in the bottom here. So if you want to change
the amount of water that actually flushes out, down the side of most of these you have two little plugs
you can actually remove. If you move the higher plug up, what that does is allow
air into the syphon and that would actually break the syphon and stop the toilet flushing. The higher up you have
this hole, the less water you will have flushing
out of the toilet cistern. And the more water you’ll
save on each flush. So there you go, that’s what I call a full flush. What we’ll do is we’ll
draw a little line on here, so we know where that came
to, that’s roughly there. What we’ll do now is
we’ll just plug that out, two of those plugs there and we’ll see how much
water we’ll roughly save. And other time that’s gonna save you thousands of litres of water over a year. So, let’s pop these out. It’s easier to get a screwdriver, you can just sort of reach in. Right so we’ve taken our two plugs out, just like that, and now we’re
gonna fill this up again. Right, let’s see how much water we save. So as you flush the toilet we should see the air sucked through this
hole here and break the syphon. There we go. And that’s broken that
syphon nice and early. Look at that, we’ve got a saving there, that’s gotta be five litres at least, probably about five litres
worth of water there saved on that flush. Just because we’ve got
a nice big box here. But just imagine over your
cistern over a load of time. So there we go, I hope that’s
given you a better idea about how syphon units work, how to save money on syphon units and also how to change that
little flap if they go wrong. If you need any more help,
or any more information, please visit our website as I said please subscribe to our videos. We upload regularly, pretty much weekly, and we also answer your questions on our Facebook and Twitter page. If you send us a Facebook
question using your mobile phone and make a little video
of you asking the question and showing us the problem. We may well use it on our next Ask the Plumber video on YouTube. Until next time everyone,
keep flushing the toilet, I hope it works okay and
remember to hold tight. – [Announcer],
honest reviews and advice.


  • Reply Max Beefsteak May 14, 2015 at 4:09 pm

    I can see your nipple

  • Reply Matt Pearson May 14, 2015 at 4:35 pm

    Someone has been on holiday

  • Reply Lewis Heffernan May 14, 2015 at 4:58 pm

    Very helpful video. Looking to replace a diaphragm soon and this video has come in very handy.

  • Reply Matthew Axon May 14, 2015 at 6:32 pm

    Yes big up ryobi love it

  • Reply David Lawlor May 14, 2015 at 7:16 pm

    What's the best plastic to use to replace diaphragm ?
    Great video.V practical

  • Reply ROBERT LAWRENCE May 14, 2015 at 8:45 pm

    You got a license for them guns fella???
    Bit more gym time on your hands these days?

  • Reply jesus jones May 14, 2015 at 9:32 pm

    Absolutely brilliant explanation!  Nice one!

  • Reply James Cole May 15, 2015 at 6:41 am

    The amount of customers I have complain of there flush not clearing the contents of the pan is crazy, your telling them to reduce the flush volume? So your logic is to have a 4 litre or so flush and flush it two to 3 times to clear the contents of the pan because lets face it thats what happens. How is that saving water? I remember the 9 litre flushes. Only had to pull the chain once

  • Reply MKRM27 May 15, 2015 at 8:16 am

    "Haircut! Haircuuut!"

  • Reply Dont Get by Get Bry May 16, 2015 at 7:15 am

    Great video mate but no sign of big G!
    Having just completed my level 2 city and guilds qualification we touched on the different flash vavles and the ability to influence the flush amount and time. I know many customers don't know you can adjust the flush time using the plugs on the side.
    Perhaps we could cover FOVs next time? There are so many types which are manufactured to the 4 and 6 ltr water regs spec.
    Keep up the good work and HOLD TIGHT!

  • Reply Sam Shepherd May 16, 2015 at 6:27 pm

    Lovely bit of product placement there 😉 Love it!

  • Reply Ryan Matts May 16, 2015 at 7:45 pm

    2 things…

    Number 1, that Lego head you have is crazy, what is it?

    Number 2, the never mind the ballcocks sticker is epic, you need to start some competitions man I need to win one!

    Hold tight!

  • Reply woodbine66 May 17, 2015 at 1:23 am

    TOP TIP – Jas

    No need to buy new syphon membranes. I use the plastic bags that my cat's (Harry) dry food comes in. Being a spoilt bugger, he gets Hills, but the plastic bags from any dry cat food will do. Just cut out the shape of the original membrane and whack it in the syphon. I've done loads and never replaced one yet. Some still going 8 years later. See George for details.

    Hold tight!!!!!

  • Reply James Cole May 18, 2015 at 4:50 pm

    @plumberparts. You haven't upset me lol. I just think its a daft idea having a 4 litre flush that you have to flush two or three times to clear any tissue etc. I know it's not your fault. Great explanation mate, keep it up!

  • Reply Robb J May 20, 2015 at 12:05 pm

    So how do you increase the flow? We have a floater problem – post curry.

  • Reply Harry Crew May 21, 2015 at 4:54 pm

    Those Ryobi tools look very smart! Like the look of the 3 battery power pack!

  • Reply Albert Matei May 26, 2015 at 10:43 pm

    I replaced the flush diaphram with laminating paper and it worked just like new??

  • Reply Zed Man May 29, 2015 at 10:31 pm

    Lovely explanation as always

  • Reply STLbluesfan1 October 15, 2015 at 2:20 pm

    I saw the ultimate handyman replace a siphon like that with a dual flush siphon with a peg you pull out to remove the top of the siphon.

  • Reply Bobbi Bister October 19, 2015 at 7:18 pm

    I had a weak flush issue from a property I bought and thanks to you its all sorted! You saved me from buying a new siphon and other stuffs which the plumber said we needed. Your video was a bit fast for me and I almost gave up listening until when you mentioned about plugging the hole to increase the flush and even the pin to release the siphon. I did it myself and it just flushes well now. Thank you!

  • Reply STLbluesfan1 October 24, 2015 at 12:57 am

    Every time I see this video, I am thinking of how a rubber hose drained my clogged sink into a bucket.

  • Reply STLbluesfan1 October 24, 2015 at 1:04 am

    And when you talked about the 2 plugs that adjusts the water being used. I am thinking of how I was adjusting the flapper float on my kohler toilet and I am able to conserve water and get the bowl refilled completely (because it's siphonic) with every flush.

  • Reply David Evans December 16, 2015 at 12:59 pm

    This video saved my Christmas…..cheers

  • Reply Laurel Hampson January 16, 2016 at 12:13 pm

    I had no problem changing the diaphragm on my siphon after seeing this video, and I'm a woman. Thanks. LH

  • Reply Clive Moss January 28, 2016 at 11:00 am


  • Reply wassupjg February 29, 2016 at 9:25 pm

    Just came from a video you did in 2011, your excitement level has increased 350%, many thanks for sharing your knowledge to plebs like me m8, very clear and informative.

  • Reply Suzanne King April 1, 2016 at 11:31 am

    Thank you!

  • Reply Andrew Walcott May 15, 2016 at 4:46 am

    Well done mate. Much thanks

  • Reply joey June 26, 2016 at 4:01 pm

    Yap just done replacing the diaphragm with some plastic from a notebook cove,r and the damn thing works like charm.

  • Reply Morgan Spear July 5, 2016 at 1:35 pm

    Thanks! Just made my own flapper & fixed the loo 🙂

  • Reply Iain Cobb September 6, 2016 at 8:36 pm

    Thank you that, you just solved my problem of how to feed my pond fish. I have thousands of water shrimp and fleas that multiply like mad in a separate tank, and have problems netting them because of the algae covered rocks they feed on. going to make a tank with a flush in it, away from the rocks of course, and plumb it from the garden shed to the pond.

  • Reply Winston Clifford November 16, 2016 at 1:35 pm

    Great Video! One question:-The diaphragm is cheap, needing to replace inconvenient, the house call for plumber repairs expensive , Could you replace the single diaphragm with two washer diaphragm sandwiched together? Would it lengthen the service life? Is there a different material apart from Plastic, say silicone rubber diaphragm?

  • Reply Roger Griffith December 15, 2016 at 5:31 pm

    Very clear and precise – many thanks

  • Reply RaptureUK1 February 13, 2017 at 6:10 pm

    Great tutorial! I have one question though. Surely the amount of water thats used in one flush it determined by the amount of water sitting in the systen tank (set by ball cock). So when a siphon is refered to as "6 litre", what does that actually mean?

  • Reply Gordon Eden March 31, 2017 at 8:32 pm

    Sorry mate but I want to know how to repair my toilet flush, not hear your attempt to try and be a You-Tube star! Tone your delivery down a bit!

  • Reply KAF Kent April 3, 2017 at 5:45 am

    the top of flush has snapped off this morning where the linkage connects any ideas ?? Help

  • Reply Valerie Green October 8, 2017 at 7:56 pm

    Just replaced the diaphragm on my toilet using this video as a guide. Thanks for the help.

  • Reply Elevator Operator October 12, 2017 at 11:51 pm

    I have a standard flapper valve toilet

  • Reply Elevator Operator November 23, 2017 at 4:18 am

    Why do they still sell siphon toilets when flapper valves are simpler and easier to install?

  • Reply Steven Harrhy December 30, 2017 at 4:21 pm

    Hi mate, changed my siphon unit today with guidance from your video, well explained and easy to understand. Many thanks.

  • Reply mgml February 5, 2018 at 10:31 pm

    Thanks, good description of how it all works.

  • Reply Raymo Mull May 6, 2018 at 10:42 am

    That's Barry Scott's brother

  • Reply Boiled Octopus May 12, 2018 at 8:48 am

    A little bit too shouty…

  • Reply 97warlock ismyname May 21, 2018 at 3:33 pm

    You lost me early on & I think its because the approach, or delivery is in super high gear.

  • Reply shamshad ali May 30, 2018 at 4:52 pm

    Dear sir today I replaced New siphon but It's not working also volume hol up & down change I try to more but didn't working also I am plumber. I need your help if upload videos about this

  • Reply John Barnes June 23, 2018 at 8:02 pm

    Do not replace this syphon for like for like or renew the diaphragm washer use a dismatablle syphon that can be repaired without taking the syphon out of the cistern a5 minute installation

  • Reply John Barnes June 25, 2018 at 12:42 pm

    Wrong syphon again ‘this guys a joke

  • Reply Tony Daniels July 15, 2018 at 5:01 pm

    great, made the repair, triffic! thanks

  • Reply Alan Lee July 19, 2018 at 12:51 am

    Thanks for the information. 🙂 I'm going to mess in the loo, now I know the problem and how to fix it 🙂

  • Reply Iain Meteorscan September 12, 2018 at 7:18 pm

    Hi plumberparts. Ignore the troll comments about being “shouty” or “trying to be a YouTube star”. You ARE a YouTube star, getting straight into the video without wasting any time, unlike most YouTube videos that are more to do with hopeless wannabe, bedroom video producers (unboxing and all that kind of time-wasting rubbish). Brilliant and straight-to-the-point. Anyone else would have taken twice the time and bored us to death. Brilliant editing, cutting out the excessive crap (pun intended) normally found in YouTube videos. Well done.

  • Reply jerry o connor September 26, 2018 at 5:52 am

    Great explanation how do I know which size siphon I need to get

  • Reply b1ueocean October 21, 2018 at 6:54 am

    can someone please clarify the "continuous flow" aspect, it's doing my head in lol
    So when the water is introduced into the panel, I can accept that a little bit of it pushes into the ciphon beyond the flaps/diaphragm.
    When you pull on the handle stick, that little bit of water is forced though (by flaps/diaphragm rising) into and down the main flush pipe.
    But how come after that first pull on the handle stick, the whole damn body of water flies up into the ciphon in a continuous stream, is there a small pump or oscillating bit inside? thanks for any insight cos I'm stumped.

  • Reply Jay Kay October 31, 2018 at 10:29 pm

    Brilliant! Thanks for explaining how the Syphon flush works! How fucking clever is that!!
    Anyway. Thanks again.
    Keep em coming! ????

  • Reply plumberparts December 12, 2018 at 10:26 am

    Links to the tools I use everyday here:

    Plus, follow my Vlog “TimesWithJames”:

  • Reply azraaell January 20, 2019 at 10:41 pm

    do you know what a thing that screws into to drain end of the siphon like an afterburner type thing?

  • Reply Paul Whyte March 3, 2019 at 3:22 pm

    Great video buddy – helped me solve my problem. Cheers!

  • Reply Ian Digby March 9, 2019 at 9:44 am

    Brilliant! Thanks so much, man.

  • Reply Nick Clark March 10, 2019 at 9:50 am

    Helped me solve MY problem anyway, thanks. Also understand something about how the syphon works. Enjoyed your enthusiasm for the mechanics of the cistern! An antidote to those rather serious and self important people who ramble on in a monotone ……. More power to your elbow (joint) !

  • Reply D Mack March 13, 2019 at 7:59 pm

    Nice one… thanks for the upload

  • Reply Jay Igaboo April 7, 2019 at 11:24 pm

    Excellent tutorial, thanks. Does what it says on the tin, no bullshit, clear diction and no wordy time-wasting, very well presented.

  • Reply dawn hoffman May 10, 2019 at 8:30 am

    Thanks just what I was looking for

  • Reply J P May 17, 2019 at 7:52 pm

    You bloody belter… just mended my syphon using a milk bottle.. thanks for the great video. I am now subscribed!

  • Reply Anthony Fewkes June 16, 2019 at 9:14 am

    Why can't Dudley do us all a favour and make a siphon with a quick release coupler which allows for the siphon to be removed without having to remove the flipping cistern. There's just nothing like trying to remove two pissy rusted bolts on a Friday afternoon.

  • Reply Anthony Fewkes June 16, 2019 at 9:15 am

    PS. Love the work.

  • Reply Bill June 18, 2019 at 2:06 pm

    Great channel is there anything on the market that will stop a toilet seat from moving from side to side,
    Supplied bolts and wings are rubbish thanks

  • Reply Michael M June 27, 2019 at 4:32 am


  • Reply Sono2 July 6, 2019 at 10:26 am

    Why is it a flimsy piece of plastic? Why not hard plastic or metal so it won't wear down?

  • Reply Hkun Htoi Layang July 14, 2019 at 2:49 pm

    Sorted after watching your video. Thank you!

  • Reply Shaun Barry July 17, 2019 at 8:54 pm

    What a great video. Thanks!

  • Reply John Gostick August 2, 2019 at 4:51 pm

    great video – really well explained and demonstrated!

  • Reply Mickey Burns August 7, 2019 at 5:00 pm

    I'm pretty useless at DIY, but I've just replaced the diaphragm in my toilet syphon after watching your video. I cut the replacement out of a 4 pint plastic milk bottle using what was left of the old diaphragm as a template. (Make sure you have a pen that will write on plastic). It took about 15 minutes and no money and I have a flushing toilet again! Thanks so much!

  • Reply Nok nRoll August 8, 2019 at 8:36 pm

    Mate great video ?? but wonder if you can help please? I just bought a toilet and installed it but the problem I m having is it splashes out the bowl when I flush it, it’s a dual flush siphon and is tied all the usuals like lowering the water level. It just seems to come out so fast that it hits the centre of the bowl. Any help would be appreciated ??

  • Reply Vippo 25 August 11, 2019 at 4:36 pm

    Thanks for the advice. By the way is your dad Bradley Walsh?

  • Reply ANTONIOS September 11, 2019 at 3:25 pm

    Thanks for all your videos. Which duel toilet siphon and water filler are long-lasting and easy to service?

  • Reply kargaroc386 October 3, 2019 at 9:36 pm

    I'm american and have never seen one of these before!

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