Drop valves versus syphon valves

[Alanka]

I reckon the relatively new 'drop valve' mechanisms are a backwards step in design, compared to the well-proven syphon-type flush mechanisms!

I understand their popularity -- you press a neat 'modern-looking' button or dual button with your little pinkie to activate the flush, as if you were switching on the telly, instead of cranking an old-fashioned-looking lever!

But I am pretty fed up with being called out to cure the drop-valve dribble, that happens when the seating seal begins to fail. I've tried cleaning the rubber washer but it rarely works for long and I end up having to uncouple and remove the cistern to replace the entire drop-valve -- at great expense to the customer who is not best pleased.

You only have to look at a modern drop-valve to see it's a crap design -- so unbelievably and needlessly over-complicated, with dozens of little plastic levers, cams, pivots etc needed to make the damn thing work!

By contrast the traditional syphon is extremely cheap and simple in principle and in operation. Its construction means that it cannot dribble into the pan. If it eventually fails to work properly you can renew the flap diaphragm without even having to remove the syphon from the cistern -- if you have had the sense to fit a syphon that disassembles from the top! The crank handle (lever) is equally simple to understand and either fix or replace. It may not be sexy but it's functional.

 

[unguided1]

Hi Alanka
when i first started plumbing it was easy to carry enough spares on the van to change the inards of most types of cistern or taps, therefore one trip, do the job, charge the customer, and off to the next job. Now you have to go to the job strip it down, take the offending part to the merchants, to compare if the merchants have the right bit, then go to half a dozen other merchants because either they dont stock it or they have run out. by the time you have got back to the job youve ended up waisting a day just running around.
So I say bring in some form of standardisation and a law stating that if a merchant wants to operate they should carry spares in stock for all eventuallitys.
regards
Mike
ps. I prefer syphons

 

[Bernie2]

Hmm!

Interesting point about drop valves. In the 1960's I worked at one point for a company that did repair work and we often went to old properties to repair leaking cisterns called compound cisterns.

Most of the cisterns where probably near on 100 years old then.

Funnily enough they worked similar to modern drop valve syphons.

So drop valves would appear to be history revisited not a new idea.

Yes! The same thing happened on compound cisterns, the valve washer leaked and yes the washers where hard to get.

 

[flat pack]

He in spain they all are,
when the cistern fail you see it turn off sevice tap.
call a plumber
or you buy for a cents
solvable in no time
beats water all over the garden or down the wall

also more work for the plumber
?unless you dont want it¿ ??

 

[johnmcginty]

What do you guys think of flapper style like the yanks have then? I have yet to see one.

 

[Alanka]

I've had quite a bit of experience with the 'flapper' type flush mechanisms it so happens (the Fuidmaster one at any rate), and have fitted several to customers' wcs, and also to my own wc at home.

I first saw this type of valve more than ten years ago on holiday in Egypt of all places, where they seemed to be the only type of valve in use. I was impressed by their simplicity (compared to the ultra-complicated drop valves) and effectiveness. Nothing much there, just a rubber flapper, a piece of string, and a little lever. (What a plumbing geek -- looking under the wc lid on holiday!! Takes all sorts.) The modern ones have a simple way of setting the flush volume, which does sort of work, but it's not something the punter can do every time he/she uses the wc.

They work really well but, of course, do have their problems. Like other non-syphon valves, they eventually start to leak as the rubber 'flapper' begins to deteriorate, stiffen and warp, preventing it from sitting properly on the seating at the base of the cistern. This can sometimes happen within a year or so, but replacing the flapper is dead easy.

Another, much more serious, problem with the Fluidmaster button-activated mech is the very poor leverage afforded by the button arrangement. It's a truly crap design. You have to press really hard on that button to get the flap to lift and start the flush -- not a good idea for the elderly or youngsters. The cure is simple: get the lever-operated version, which is far better designed and is in fact much easier to crank than the average syphon lever. (The ones in Egypt all had levers, not buttons, because they didn't suffer from the button-pushing fetish that seems to have infected most of the world now.)

When fitting a flapper mech you do have to get the length of the chain (that lifts the flapper valve) just right, which can be a bit fiddly. Too short will damage the valve or snap the chain (if it's a plastic one) -- too long and the flush wont initiate properly because the valve isn't lifted high enough to stay open. Additionally, I've been called back when a mech was flushing non-stop because the chain had become twisted on itself making it too short to let the flapper fully close. I shortened the chain a link or two to prevent this happening again.

Other than that I reckon this type of valve is pretty good, and certainly a damn-sight better than the average drop valve. I'm very happy with mine, but I still prefer a top-access syphon for longer-term reliability.

 

[GaryTheGolfer]

I reckon the relatively new 'drop valve' mechanisms are a backwards step in design, compared to the well-proven syphon-type flush mechanisms!

I understand their popularity -- you press a neat 'modern-looking' button or dual button with your little pinkie to activate the flush, as if you were switching on the telly, instead of cranking an old-fashioned-looking lever!

But I am pretty fed up with being called out to cure the drop-valve dribble, that happens when the seating seal begins to fail. I've tried cleaning the rubber washer but it rarely works for long and I end up having to uncouple and remove the cistern to replace the entire drop-valve -- at great expense to the customer who is not best pleased.

You only have to look at a modern drop-valve to see it's a crap design -- so unbelievably and needlessly over-complicated, with dozens of little plastic levers, cams, pivots etc needed to make the damn thing work!

By contrast the traditional syphon is extremely cheap and simple in principle and in operation. Its construction means that it cannot dribble into the pan. If it eventually fails to work properly you can renew the flap diaphragm without even having to remove the syphon from the cistern -- if you have had the sense to fit a syphon that disassembles from the top! The crank handle (lever) is equally simple to understand and either fix or replace. It may not be sexy but it's functional.

I absolutely agree with you. I have had nothing but trouble with drop valves.

They have had these in USA for over 100 years.....and they still can't get them to work.

The UK versions seem to use a stiff Bowden cable that manages to pull the drop tube off centre and consequently stops the valve from seating squarely. The resultant dribble is just stupid.....by design

 

[jonathanb]

They all end up causing probs, did a wing of a hotel with saniflows and they kept going off at all hours due to drop valves leaking into the pan. Guests not happy - Not do that again!....

 

[stevetheplumber]

They all end up causing probs, did a wing of a hotel with saniflows and they kept going off at all hours due to drop valves leaking into the pan. Guests not happy - Not do that again!....

best cisterns i ever worked on were over 80 years old two inch tapered hole in the bottom two and a half inch rubber ball on a rod which protruded thru the lid lift the rod and you let it flush as long as necessary never leaked never needed mending in ten years i was working on them and i suspect they were original fittings

 

[Phil]

Fluidmaster do a drop valve for under a tenner, they are cable operated with two simple sliders to adjust short and long flush volumes.

They are much better quality than the multiquick and opella ones and I've fitted a few now with no problems.

 

[david williams]

to stevetheplumber if you find one now collectors item ,especialy if a thomas craper

 

[Hugh]

Im with B

 

[stevetheplumber]

i dont mind the drop type valve if only they would standardise the coupling in the cysten so we could just carry one or two spares

 

[colinb]

Hi
New to the forum, great to find lots of valuable ideas and advice.

I am renovating a large old house in Scotland & have come across problem in the bathroom I am currently working on. The cistern is made of Mahogany with a copper lining and this has a drop valve flush which is the tapered seat and cone shaped washer type previously mentioned. Well after many years of service the washer has started to perish, I say washer its more of a bung about 2.5 inches in diameter, and 1/2 inch thick. I know it a VERY long shot but does anybody know of a supplier keeps old washers in stock.

The cistern is more like a piece of furniture so I dont want to change it. I thought of trying to make a new washer from solid rubber ball drilled through centre (on lathe) and then cut across at required diameter. If that fails will have to look at inserting new cistern into existing wooden unit.

Any help or suggestions would be welcome.

 

[stevetheplumber]

Most unusual set up for a cysten that ive worked on was an electric flush
it was a back to wall pan with the flush pipe in side the studwork the cysten was in the loft in side the cysten was a small garden pond pump with the small flexible pipe from the outlet pushed up and over the syphon opereated fom a push button next to th wc

the other unusual cysten were at the albert hall about 20 pans in a row had a shared tank the length of the block with a bell syphon for each pan operated by a chain thru a pipe inside the water filled tank
this meant the toilets could be flushed instantly again and again to cope with the crowd rushing in during the interval some how they had a small tube on the syphon which regulated the flush (memory is dim its over 30 years ago)

Forgot to add imin total agree ment with the first post here and the answer is some standardisation of the fittingin the cysten base but will it happen . No we used to have standard flues which fitted all boilers this is another area that should be standard ised preferably with the keston system not mad about the boilers but the flueing options are great