DIY Doctor UK DIY Forums

I've just replaced a faulty bottom-entry fill valve, but when the water is off, its leaking down the thread (i.e. from the cistern).
I think the problem is that the replacement valve is 15mm (same size as the inlet water pipe), but the original appears to be around 20mm (it had a width reduce under the cistern, and I couldn't find a valve this size).
So, the hole the valve protrudes through is larger than it should be, and the seating washer isn't sealing it properly.

Water is dripping through (slowly).

Is there some viable way of reducing the hole in the cistern to make a good seal? I've tried the washer that came with the new valve, and also the old valve - with both the valve has some sideways play because of the width of the cistern hole.

I've attached pictures from underneath and inside the cistern.

Thanks!

Hi kevinrdixon
There are rubber washers on the market which are conical in shape rather than flat, some bottom entry fill valves are supplied with them. Not sure you can buy the separately - search the internet.
Regards S

The new valve came with a shaped washer. I think its probably just not wide enough for the hole in the cistern - its a 15mm valve, but it appear that the cistern is American (the hole is 1" and old valve has 15/16" threaded inlet).
I've tried searching for conical, doughnut and rubber gaskets but found nothing suitable.

Why on earth I have an American-sized cistern I do not know. IIRC came from Bathstore.

Last resort is another fill valve in American size... failing to find any of those either.

Hi kevinrdixon
You could try fitting a cold water tank overflow boss to reduce the diameter and fit the fill valve inside this. Check the diameters are suitable and you may have to reduce the length of the boss to suit.
Regards S