Loud bang when cistern filling

[Toughie]

Hi,

We have recently had two bathrooms renovated. When we flush the toilet in both bathrooms we hear a loud bang when the cistern has finished filling. The thud can also be heard from the airing cupboard.

We also hear what sounds like a pipe rattling loudly as the cistern starts to fill in the main bathroom.

Both bathrooms have ALCA concealed cisterns with an A160P cistern/fill valve which is down as "smooth closing" in the features list.

We have a pressurised system with a pressure reducing valve and have no issues or noises when using any taps/showers or baths.

Any idea what could resolve this issue?

Thanks for any help.

 

[Wayners]

Water hammer.
Fit water hammer arrestor on toilet.
You can try turning stop tap back a bit and see what happens

 

[Harry Bloomfield]

We have recently had two bathrooms renovated. When we flush the toilet in both bathrooms we hear a loud bang when the cistern has finished filling. The thud can also be heard from the airing cupboard.

Often caused by a high mains pressure, and too quick a flow, filling the cistern rapidly. You could try reducing the speed of the fill, either by adding an isolating valve in the supply pipe to each, and not turning it on fully, or...

You can fit a disc, with a small hole in, where the pipe connects to the fill valve - these are often used to slow the flow into a washing machine.

 

[Toughie]

Thank you both for your responses.

Is this stuff that can be accessed through the flush plate? The bathrooms are complete with the in wall toilet frames tiled in.

 

[Harry Bloomfield]

Is this stuff that can be accessed through the flush plate? The bathrooms are complete with the in wall toilet frames tiled in.

Test the limiting the flow first, by turning your stop tap down, and flushing - see if you still hear the thumps.