New toilet cistern parts, now get severe water hammer

nicknike · Jan 29, 2016

Hi all. The syphon failed, so I fitted a new Fluidmaster flush valve with side handle which is very good.
I took advantage of pulling the cistern apart to fit a new bottom entry fill valve, namely a Skylo type. The original took forever to fill. I won't bore you with the details but I want a reasonably quick fill. The new fill valve must shut off too quickly as I get severe water hammer now when the valve shuts. I have reduced the main stopcock to reduce flow, and I have partially closed the cistern isolation valve. I now detect a little hammer, but the general house flows are now too low. So I really want to open the stopcock and isolator and attack this hammer another way.
Can somebody please advise what I can do? Can I fit an alternative fill valve that will not cause hammer. It just needs a valve that will shut more slowly.

Incidentally, just after the main stopcock is an inclined pressure reduction vale set to 3 bar, made by Caleffi.
Can I reduce the pressure with this valve and cure the hammer, whilst maintaining a reasonable flow?

Thanks for any help.
Nick

Best · Jan 29, 2016

Hello Nick. I wouldn't turn the main stopcock down. All that does is reduce flow everywhere and will not reduce pressure. 3 bar is about what you want. You might be best to have the pressure checked as it is always possible that the PRV and gauge could be faulty.
I would recommend you fit a Fluidmaster Pro valve with brass tail. It should be the type with a red top. It comes with a 'screw' type insert for flow reducer

gassafe · Jan 29, 2016

Defs fit a fluidmaster...

Cheers for the heads up on the viva skylo too, I will stay away lol

nicknike · Jan 30, 2016

Thanks. Will try the Fluidmaster Pro. It says in the specification it is height adjustable 230mm-355mm. Is this the water level? My cistern water line is 195mm.

Thegift · Jan 30, 2016

nicknike said:
Thanks. Will try the Fluidmaster Pro. It says in the specification it is height adjustable 230mm-355mm. Is this the water level? My cistern water line is 195mm.

The fluidmaster pro will fit fine, it's telescopic so can easily be adjusted to fit, a much better fill valve

nicknike · Jan 30, 2016

Many thanks. I can see it's telescopic, but was concerned about the heights 230mm-355mm given. Are these water heights or overall height of the valve? My water line is at 195mm, that is, 35mm below the minimum height given for the valve.

PhoenixServices · Jan 30, 2016

That is height of valve not water level.

nicknike · Jan 30, 2016

Thanks guys. Nice friendly and useful responses. Now on order for delivery tomorrow.
Nick

nicknike · Jan 31, 2016

The Fluidmaster Pro valve now resides in my cistern There is absolutely no evidence of water hammer whatsoever, and it fills in a very acceptable time even with the flow restrictor fitted. Many thanks guys for the help and particularly Best who originally recommended this valve. I also have the main stopcock opened to give maximum tap flows, etc, and the cistern isolator fully open again. I will stick with Fluidmaster products in future. The Viva Skylo products cause problems in my opinion.