"Ted" wrote in message
...
Newbie question..... Does the change in outside temperatures affect
plumbing
pipe noises in the wall? When an upstairs toilet is flushed, I hear a
knocking noise in the walls. It's not a drip, it's a knock. It seems,
however, that I'm now hearing a knocking noise when I flush any toilet in
our home (two story). I had a plumber out initially who advised that it
wasn't a leak/drip but rather a pipe that probably wasn't fastened. I
have
an associate who's a plumber that said the same thing. We have no
evidence
of water damage, leaks etc. but it seems to be more prevalent now that we
have colder temperatures. Can colder outside temps (teens) affect
plumbing
noises? Help.

It could be just a case of air hammer, caused by no air in the system water
dose not compress so the air acts like a shock absorber. They might of piped
air chambers in the system. ( it's a good practice) What you need to do is
turn the water off drain all the water out and then refill. In time the
water absorbs the air and you lose your cushion. Cost nothing can't hurt you
never know might solve the problem.