I just brought a house six months ago and this winter when I turn on the hot water and run it about 5-10 minutes. The pipe like knocking the dry wall or something. After about 5 minutes it will stop. Usually this occur after shower or large amount of hot water is used. I am wonder this will be cause any danger? I have no way to take a look at since all the pipe is behide the wall.

Please advise.


Thanks
Susen

Knocking, popping, creaking and crackling pipes are a common complaint, especially in colder weather. I can tell you what's happening and take the mystery out of it but you're not going to like the repair. When a draw is made on a hot water line the line expands against a pipe strap next to a stud and when you drain hot water from your tub or shower it goes into a chase that is a little cooler then room temperature. The heat expands the pipe causing it to rub against the stud to which it is pipe strapped. This is the sound you hear. As it cools it contracts and the noise is heard again. To repair it you must tear open the walls and locate the pipe strap that's causing the problem and shim it tight. Most people when they learn what causes it just elect to live with it. Regards, Tom