Hello
Around a year ago my toilet was not shutting off properly and a plumber changed what I think is called the flush valve and fill valve. Since then I have had a slow increase in water hammer when flushing the toilet. It was not noticeable at first but now is like a jackhammer.
Recently I have been timing when it happens. I have my hot water programmed to come on at 05:30 - 06:30 & 20:00 - 21:00. What I have noticed is that the banging only happenes within these times or up to 30 mins after. It mainly happens when I flush the toilet, but has started happening completely on its own. When faucets are open there is only a minor tolerable bang.
I have had another plumber recently change some faucets and parts in the toilet to no effect. As the water hammer is usually first thing in the morning and late in the evening no plumber has been able to witness it for themselves.
I have tried the turning off at mains and draining the faucets and pipes trick but after a day of two it comes back. I believe it has something to do with when the boiler is on because it happened more often in the winter which may be related to having the heating and hot water on.
Any thoughts or recommendations?