Cistern Water Suppy Issue

[Plumb37]

Hi,

I’ve just replaced my WC cistern fill valve (bottom feed) with a brand new one from Toolstation as the cistern wasn’t filling up. The water feed to the cistern has an isolating valve which seems to be working fine.

After fitting the new valve the cistern filled up and flushed 4/5 times as it should do but then just stopped filling up reverting back to the original problem.

Before fitting the new fill valve I changed the washer in the original one and the same thing happened.

This makes me think there must be an issue with the water supply coming in but I have never seen a cistern fill correctly 4/5 times and then stop filling.

Any advice would be really appreciated.
Gary

 

[Plumb37]

How about connecting a pipe to the cistern feed and running it to the toilet or basin then open the isolating valve and see what happens over time?

I’ll try that as well. Thanks

 

[Deleted member 96286]

If your bathroom is fed from the same cold water supply, try running the cold bath tap and see if it spurts out after a while. Could be air getting trapped in a dip in the gravity fed cold water supply from the storage tank, especially if the supply was turned off. Check the gate valve too, these are notorious for jamming and may not be fully opened. Running a 3/4 bath tap from the same line should help clear any air. I much prefer the Fluidmaster fill valves, as they are fit and forget.

 

[Plumb37]

Thank you for all the advice it really is appreciated.
I believe it may have been air in the feed as after running the supply into a bucket several times it appears to have corrected itself and is now filling up nicely.

 

[rpm]

Yee Hi!!!!!

 

[Welder]

Ric's answer is my 'goto'. Don't tell him tho 🙄
Had that happen too many times NOT to check.
100% issue is in supply to cistern.
Best to disconnect iso, put flexi on it and into bucket then turn on water to push through 'crap'. Most of time it drop away through water when pressure is off so you must do the flush thing to push it out. 😉

 

[Deleted member 96286]

As I said above, these low pressure issues are normally caused by air and I've had to clear these many times, number 2 is a half stuck gate valve.