Noisy toilet, what's the cause?

[Trebby]

Hi all,

We have a tall Victorian house. Toilet on top floor (4 floors above mains inlet) has always been a bit dodgy but never like this. We don't use it very often so not sure when issue started - probably in last few weeks. Recently had an unvented cylinder put in basement and they balanced most of the cold water pipes (though some to garage weren't balanced).

Now when flushing toilet in top floor there is a very loud foghorn noise. Lots of vibration of cold pipe supplying toilet and also neighbouring sink. Resolves instantly when cold tap opened. Lasts for 30 seconds or so. Have taken top off toilet and only seems to happen when ball-cock valve is fully open - if I lift it up a bit it stops instantly, until I let go.

Looking online I'm not sure whether this is due to water hammer (but we've never had it before and I don't see why the unvented cylinder should affect this as pressure in cold supply shouldn't have increased), an air lock somewhere, or the cistern valve which is broken.

Would be very grateful for any advice you can provide before I start trying to fix!

Many thanks in advance.

 

[muggles]

The washer in your ball valve is vibrating

 

[gasmanstu72]

if the toilet supply is now on the mains (before it was low pressure tank fed) you'll need to change the seating washer in the ball valve, (or change the whole valve)

you'll have this in there at the moment,
https://www.screwfix.com/p/arctic-products-low-pressure-ball-valve-seating-washers-22mm-5-pack/8136j

and you'll need to change it to this:
https://www.screwfix.com/p/arctic-products-high-pressure-ball-valve-seating-washers-1-5-pack/9478j

the difference is the size of the orifice, high pressure is smaller. it's not a difficult job if you're quite handy

 

[Trebby]

Hi,

Thanks very much for the replies - very helpful. I'm pretty certain the toilet supply has always been mains pressure - there were tanks in the attic but they were gravity supply to the hot water I think; does that seem plausible? Looking through other threads I noticed this thread (https://www.diynot.com/diy/threads/toilet-cistern-ball-valve-dripping-which-washer-part.477295/) where the setup looks identical to mine; and thought I might just replace the whole fill valve with this (https://www.screwfix.com/p/fluidmaster-bottom-entry-brass-shank-fill-valve/47792) as it has always been a bit dodgy. I presume that is likely to fix the issue?
Thanks again.

 

[Nige F]

That valve from Screwfix is ideal

 

[Trebby]

Hi guys

More help please....
I bought the new valve and thought I wa doing really well....even added an isolation valve to the plumbing. But it was very tight going it getting past the siphon, and it just catches, either on the ceramic, the siphon or the flush handle and won't reliably stop the water intake. I've tried it in lots of different positions but can't make it work. The siphon is a dudley t88 which I replaced a year or so ago as the old one dripped. Any solutions? I don't mind replacing the siphon again, but is there one that is likely to be small enough? Or shall I just buy a new one with a ball? Photos attached. Thanks again.

 

[just pumps]

Piece of hosepipe wedged in at the top will move it over so the float floats.

 

[Bosswhite]

Fit a flapper valve instead of the syphon