Toilet not flushing

[ray.love]

I have had my toilet for about 6 years & recently it stopped flushing properly (it had been fine up until then). I correctly identified that the diaphram had split & I fitted a new syphon. The cistern is close coupled so I removed this & refitted with a new fitting kit.

After fitting it, my toilet would not flush at all. I adjusted the water level to the maximum possible, just below the overflow, however, the syphon just would not start. I dismantled the toilet again & noticed that the diaphram was the same shape as my old syphon, which had previously worked OK. I therefore removed the new diaphram & fitted it in to the old syphon. Re-assembled the toilet again - this time I could make the toilet flush but it was not easy, often taking several attempts & having to wait several minutes between tries as a quantity of water would have been thrown over the syphon (but without starting it).

After a week this became such a pain that I decided to have another go. First of all I bought one of those push-button, flapper types, however, after fitting it in the cistern & reassembling the toilet, I came to fit the button only to find that it was too big to fit in my handle hole! There didn't seem to be any way of modifying it so off came the toilet for a 4th time & I purchased a second syphon (I had disposed of the previous one after I had switched the diaphram). This one also refuses to start properly. Again I have the water level at maximum & I find that two sharp pumps on the handle will get it going most times, however, still below acceptable standard.

All these syphons are basically the same as my original with only very minor differences in shape. They are the same height. Any ideas why my original one used to flush easily but my new ones don't? I've tried experimenting with moving the bungs that determine the volume of water used in the flush & this makes no difference. There is no blockage in the bowl - once the syphon starts the toilet flushes fine - it's just very hard to get the syphon going! I'm particularly puzzled as to why my original one worked fine until the diaphram split but would work properly with a new diaphram. Help!! I don't really want to have to buy a new cisterm when this one is only 6 years old & in perfect nick.

 

[Agile]

The siphons are available in three heights!

Could it be the units that you are fitting are too tall for the water level?

The top should only be about 75mm above the normal fill level.

Tony

 

[ray.love]

Thanks.

Yes, all three siphons are the same height. I hadn't heard the 75mm guideline but its within that. I have two other toilets & I had compared them - the other two siphons are the same height above the waterline as the problem one (though the cisterns & siphons are a different make/ design - they flush instantly with no effort at all). As I said, I've even tried re-fitting the same actual siphon with a new diaphram. It was hard work getting that to flush as well, even though it was OK before the old diaphram split, and even with the water an inch or so higher than it was before.

 

[Gasguru]

Are you connecting the C link to the correct hole position on the handle's plastic lever.

Perhaps when you operate the lever it does not cause a sufficient quantity of water to run over the valve top to initiate syphonage.

 

[Softus]

Interesting one.

First of all, if you flush without using the handle, what happens?
I mean pull firmly (but not abruptly) upwards on the C link.
Any easier?

While you're doing this, observe if there's any jetting of water from any part of the siphon body. You might think that you've blocked holes, but you might not have.

Have you disassembled the siphon at all? If so, is it at all possible that you've fitted the diaphragm washer below its support instead of above it?

What make is the siphon? Is it cheap cr*p or a decent one?

The bottom line is: if the siphon washer is intact and the siphon body isn't mis-shapen, then the washer will lift water and start the siphon process. If it isn't lifting the water then it won't.

 

[ray.love]

Gasguru, my cistern is a slightly compressed shape with a bow front which means that the handle is closer to the siphon than usual. This means that the plastic connector is shorter than usual & only has one hole. I see where you are coming from here. This means that the for any given movement of the handle the piston will be raised less. I hadn't thought about that - this is why my other toilets flush oh so easily & why the handle on this particular bog always needed a longer "swing"! Anyway, I can confirm that despite the handle having to be moved a greater distance, the piston does travel right to the top AND the water rises to the top of the siphon.

Softus, yes I have tried pulling the s connector by hand & no, I cannot see any jetting. As mentioned above, the piston seems to lift the water OK, it just doesn't start the siphon unless I give several quick succesive pumps, & even then not every time. I did fit a new diaphram to the original siphon which worked before the old diaphram split, but I did re-assemble it correctly. I don't think I have a cheap one. The 1st one I bought was from Wickes - it looked cheap & I noticed that the diaphram was missing (!!) so I returned it straight away & purchased one from a plumbers merchant. It looked much better. The last one was from Homebase - looked similar in quality but cost more (£12.99).

I'm thinking that if the siphon wont start then there must be an obstruction. I cannot see anything, & once the water does flow it flows freely. As the cistern is close coupled, could it be that the threaded end of the siphon is sitting very close to the porcelin of the toilet bowl, thus causing a bit of back pressure when the water first tries to expel the air? It didn't do this before I had to repair the diaphram & as I say, I have tried using the same siphon that originally worked OK, & now that doesn't work. If the new doughnut is thinner, I guess that might explain it, though it looks pretty thick & the screw holes that hold the cistern on the wall still line up. Then again I suppose the distances we are talking here area few mm's so might not be noticeable. Any thoughts before I remove it from the wall again??? Should I try saw a half inch off?

 

[petetheleak]

Only had a brief read of your problem M8 ,Cutting anything aint gonny solve the problem
A wee suggestion Try a shorter syphon .
They aint that expensive to buy at merchants.
Are you getting the correct pull when you operate the handle ?
You may have had the wrong size fitted in the first place and been fortunate that it worked ,
Can't think of anything else without looking at set up.

 

[ray.love]

Yeah, I had been thinking of doing that but I've tried overfilling the cistern to within little more than an inch of the top of the siphon & it still wont work properly. Even at normal water level the water does get to the top of the siphon. The top bit's coloured plastic so I can't see exactly what it does before falling back, but clearly something is stopping the siphon effect from going.

I've tried "dry pumping" my old siphon then doing the same with my hand near the outlet to create the back pressure that I was wondering about. You can feel the air pressure on your hand & the diaphram makes a noise when I bring my hand close, which does suggest that the effect of that pressure does travel right back up the tube. My thoughts are that this might just slow the water enough at the top of its travel to send it back. If the end is very close to the porcelain (& I haven't yet checked)then a few more millimeters clearance might allow the air to escape without backing up the pressure in the pipe.

 

[ray.love]

Well, I cut a bit off of the end of the siphon & whilst not brilliant, things are definately better. I can live with it now. I did pour some water directly into the inlet on the toilet & observed the way it swirled around before ejecting into the toilet. There was no blockage but this must cause some back pressure when the water reaces the bottom of the siphon tube & shortening has indeed helped.

 

[jay1]

i had a similar sort of problem the other day, and found that before flushing if u pulled the handle up a tiny bit it would work fine, but as you have already tried the c link i dont think that is gonna solve your problem, but you can try it.

 

[Gasguru]

It would have been interesting to have set the cistern on a couple of bits of 2x2 in the bath just to see how it performed. Perhaps with no restriction it would be OK.

Another thought (but clutching at straws) perhaps the exit holes around the rim are scaled up causing more restriction.

 

[ray.love]

Don't laugh but I did try what you suggested (sort of). I sat backwards on the toilet with the cistern on my lap with the discharge tube between my legs! It did seem to perform better but as this was a somewhat precarious position it was a little inconclusive. I couldn't be bothered to struggle again & the fact that it worked without the usual frantic pumping was enough to convince me that I should saw a bit off. I wish I'd taken a bit more off now but I can live with it as it is at present.

I have a water softener so scale shouldn't be a major problem.

Thanks for your help & opinions on this - much appreciated!