How do I fix overfilling cistern (Dual Flush Syphon)

[ahlondon]

The issue is it fills with normal water pressure up to around 6 litre, well below 6L marking and overflow pipe, but over half an hour it reaches the overflow pipe. I have tried lowering the bit on the right shown in the photo to its minimum so it's well clear of the overflow when it stops, but there seems to be a trickle feed that continues .

 

[Alec_t]

Could be the fill valve is passing. Possible culprits are a worn or dirty seal, or (less likely) a leaky float.
Alternatively the flush valve is leaking and the fill valve has to make up for water loss by opening partly.
The flush valve top looks to be detachable near the base for maintenance.

 

[ahlondon]

Could be the fill valve is passing. Possible culprits are a worn or dirty seal, or (less likely) a leaky float.
Alternatively the flush valve is leaking and the fill valve has to make up for water loss by opening partly.
The flush valve top looks to be detachable near the base for maintenance.

Thanks. Do you think changing the entry valve with a new one like the one below will solve it?

 

[Alec_t]

Yes, if indeed the entry/fill valve is the culprit. But if the top part of that valve is detachable (the black thing in the pic looks lile a retaining clip?) dismantling and cleaning the valve might do the trick.

 

[CountryFan]

Looks to me like the float is sticking, can you twist it without causing a leak underneath?

 

[ahlondon]

Yes, if indeed the entry/fill valve is the culprit. But if the top part of that valve is detachable (the black thing in the pic looks lile a retaining clip?) dismantling and cleaning the valve might do the trick.

thanks. i think i'll just buy and install a new one for a tenner.

 

[ahlondon]

Looks to me like the float is sticking, can you twist it without causing a leak underneath?

i did take it out completely to lower and refit it thinking that would solver overfilling but it seems to be float, thanks. i think i'll just buy and install a new one for a tenner.

 

[HERTS P&D]

Replace the fill valve with a brass bottom Fluidmaster:

Fluidmaster 1/2" Brass Shank Valve

• 1/2" heavy duty brass UK shank• For use in a toilet cistern or storage tank• Ultra quiet• Minimal water hammer• Long life performance• Fast refill

www.toolstation.com

Andy

 

[ahlondon]

Replace the fill valve with a brass bottom Fluidmaster:

Fluidmaster 1/2" Brass Shank Valve

• 1/2" heavy duty brass UK shank• For use in a toilet cistern or storage tank• Ultra quiet• Minimal water hammer• Long life performance• Fast refill

www.toolstation.com

Andy

Thanks, already ordered from screwfix.

 

[HERTS P&D]

Don't forget to replace the fibre washer.

Andy

 

[ahlondon]

Don't forget to replace the fibre washer.

Andy

The rubber washer sitting inside where the hole is going to external for the inlet?

 

[Alec_t]

I think the 'fibre washer' is the one in the fitting on the supply pipe which connects to the inlet valve.

 

[ahlondon]

I think the 'fibre washer' is the one in the fitting on the supply pipe which connects to the inlet valve.

I'm sure the ordered unit will include it!

 

[Alec_t]

I'm not so sure it will, but good luck.