Help with toilet cistern

[johnnyb47]

Hi
Im absolutely useless with plumbing and could do with a little advice. My toilet cistern has the annoying habit of not stopping when refilling. Its the type that has two buttons on the top for a long/short flush. The problem only seems to occasionally occur in the morning. The water pressure were i live is very strong, and have noticed that the water entering the cistern via the valve assembly overwhelms it and jets out in all directions. When i turn the basin tap on the pressure naturally drops to toilet and the water enters properly.
I'm hedging my bets water pressure is alot higher in the early hours of the morning as nobody is up in the adjacent houses consuming water, and the higher pressure in turn is overloading the cistern. This to me seems logical as this problem only happens very early in the morning) (abait rarely). There is a small water isolation tap feeding the cistern. Should i just simply turn the pressure/flow rate down or am i barking up the wrong tree.
Sorry for my complete ignorance but i thought I'd ask the question here and get a more informed clue to what's wrong,
All the very best,
Johnny

 

[Deleted member 26715]

You could try that, or if you look at the buttons themselves where they go into the surround is there any build up of corrosion? Sometimes in hardware areas you get a little built up which needs cleaning off, the other thing to try is to lower the float. Switch off the water at the isolator, take off the top & you will see the float. You need to move the float down a few millimetres.

 

[Milkfloat]

If it never happens when the pressure is low then turning closing the isolating valve slightly will help and is very easy. As well as doing this I would check out the valve and float like Phaeton says as that might be the root cause.

 

[johnnyb47]

Many thanks for your advice. I think the valve must be incased in the separate plastic gubbins as i cannot see it. In the centre of the cistern is an overflow pipe that feeds in to the toilet as well as the plastic housing that contains the flush mechanism. To the left is the inlet. When it doesn't stop filling the overflow can barely cope with the excess water which is somewhat worrying as it may over flow and cause a flood.
Once again many thanks for your help.
It's greatly appreciated 👍👍

 

[Tigerbiten]

Turning that valve will drop the pressure on the cistern valve at full flow.
But as the cistern valve closes then the pressure on the valve must rise back to the original high pressure.
So you may get a better/slower fill.
But if the water pressure is overwhelming the valve then it won't make much difference.

Luck ............

 

[johnnyb47]

Ahh yes. That makes sense buddy. May be its not so much the pressure but the violent rate the water entering the system
Many thanks to you 👍

 

[Deleted member 26715]

The overflow should be diverted into the toilet bowl so should not cause a flood it's just wasting water

 

[johnnyb47]

Absolutely but the rate the water that enters the cistern virtually overwhelms the over flow to the point of flowing over. For this reason alone i think it wise to stem the flow abit with the isolation valve. After growing up with a dad who burnt the house down with his dodgy electrics and flooded it with his dreadful plumbing I've stayed well away from understanding it. (he's scared me for life lol)

 

[sleuthey]

It sounds like you have a modern type (vertical) Syphon where repair is normally by replacement so there won't be a Ball Cock that you can adjust.

Closing the Appliance Valve will NOT lower the pressure but it will lower the flow rate which will certainly address your concerns about the water inlet Flow overcoming the overflow pipe.

 

[berty bassett]

Sounds a lot like the float ( upturned cup shape thing ) is catching on the side of the cistern , only slightly , so sometimes it slides up and stops flow , sometimes sticks and the water overflows into bowl. If your lucky and brave you can reach in and should be able to twist the base of the gubbings enough to miss the side of cistern without issue
If your not lucky and you snap something I find curling up in the bath weeping to yourself eases the pain

 

[johnnyb47]

I've just turned the isolation valve slightly down and the noise in the pipes is very loud. (like a mad rush of water)
On closer inspection of the cistern gubbins i think ive identified the float. (How stupid of me not to see it in the first place doh)
It's attached to the plastic part of the inlet assembly which rises up and in turn pushes a lever at the top. This then must push down the valve to stop the water. I wonder if it is the float thats getting stuck all the time. I shall have to investigate more i think 👍🤔
You've all been a great help
Chat Chat saves the day again🎉

 

[DaveReading]

A photo might help if you're still having a problem.

 

[Drago]

If you have a water meter you can reduce your in house pressure by turning down the c ock at the meter. If its excessively high and causing you issues it's easy to do.

 

[Brains]

Are you in a hard water/limescale area ?

Small build up of limescale in the valve can cause issues like this
Just chip off all the limescale and you will be OK (for a few months ......)

 

[johnnyb47]

I'll take a photo as suggested later on. I've got a 60 mile trip to do shortly A work mate needs picking up from hospital after undergoing surgery. Certainly no cycling for me tonight