When flushing the toilet in my master bathroom I hear a clancking noise in my wall just as the toilet finishes filling up. I am thinking it is water hammer and should install a hammer arrester but just want some other opinions. If I should install this device where would the best place be to install it? Thanks
It probably is water hammer. Try changing the fill valve to something like a fluidmaster 400. The only place a hammer arrestor would do any good is right at the shutoff valve and you won't get one to fit in that space.
Always ask to see your contractors license!