Water Hammer has Suddenly Started

[sigmund]

I have had no problem for the last thirteen years. However in the last few days when the cistern of my WC has filled there is a 'bomp' noise. The cistern has a FluidMaster system and the rubber valve is new. I have an unvented hot water system and there is no problem on the hot water side. I therefore do not have a cold water cistern. The only tank I have is the small header tank for the boiler.

What is even more worrying is that in the last few days we sometimes hear a 'bomp' at night when none of the taps have been used or the WC flushed and the boiler and hot water systems are off. What on earth could cause this?

Can anyone suggest a solution to cure the problems?

 

[Bahco]

Turn down your stoptap a bit.

 

[sigmund]

Thanks Bahco. But why does it go 'bomp' in the night when nothing is being used?

 

[Bahco]

Maybe the valve is sticking and then manages at some point to free itself.

Investigate it by keeping a record of when it happens etc and you will soon pinpoint why.

 

[onlyfitidealboilers]

have you a water meter? fit a mini expansion vessel to the cold main or a shock arrester

 

[sigmund]

Thanks for the suggestion. But, before I call a plumber in on what sounds like an expensive job, why should the problem only have started in the last few days after 13 years without any difficulties? Is there any other things that I could try first?

Obviously I already have an expansion vessel on my unvented hot water system, but all my cold water is mains fed.

 

[sigmund]

Sorry. I forgot to mention that I do have a water meter