Violently shutting drop valve

[MarkB]

Hello,

I recently installed a WC (supplied with drop valve) for a customer and they are reporting that when it shuts after a flush it shuts with a real bump, so much that it rattles the cistern lid!

I have already been out to look at it once, as initially it was only happening on the half flush. I put this down to the increased weight of water remaining in the cistern after the half flush as I couldn't find any other fault with the valve.

The customer is now reporting that it is happening on both the full and half flushes.

I know all drop valves shut with a bump but this does seem to be much more than usual.

Does anyone have any ideas as to what is causing this?

Thanks

Mark.

 

[feltham]

is the cold main touching another pipe or not cliped propperly as this can cause the pipe to move and hit the pipe. this happens when the toilet is flushed it lets water in quickly and shuts quickly and makes the pipe move. it happens round my sisters house the previous owners put socks round the pipes to prevent it but didnt make a bit of difference but i have got to move and clip pipes when i install their new bathroom.
you could install another ball valve if this is the case . just let more water in the cistern and let it shut off quickly and if the knock happens then you know what it is

 

[MarkB]

Hi Feltham,

It's not the float valve but the drop / flush valve. It's push button operated with the button on the cistern lid and when the flush has finished it's the closing of the flush valve is causing the bump. I hope this makes sense

It's a bit like this (but not this Dudley one)


Mark

 

[dontknowitall]

Please excuse the layman's language, but would one of those squigly things to reduce the water flow rate help?

Having read the post again I'm not sure it would, but you never know.

 

[MarkB]

Please excuse the layman's language, but would one of those squigly things to reduce the water flow rate help?

Having read the post again I'm not sure it would, but you never know.

Unfortunately not 🙁 - it's not the fill rate from the float valve that is the problem.

Mark

 

[Bernie2]

Not to over complicate things, try a bit of silicon spray it may be catching at a certain point, then suddenly jumping loose and banging onto the seating.

You know what plastics like, if everything is not spot on and in line.