This is a new house, 2 story. When I run hot water in the upstairs after a few seconds the drain pipe or the vent stack makes loud cracking and popping sounds due to thermal expansion which of course is worse in the winter time. It's coming from the interior wall of the main stack between the first and second floor. Does anyone have a suggestion to cure this?

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Originally Posted by DaveeR

This is a new house, 2 story. When I run hot water in the upstairs after a few seconds the drain pipe or the vent stack makes loud cracking and popping sounds due to thermal expansion which of course is worse in the winter time. It's coming from the interior wall of the main stack between the first and second floor. Does anyone have a suggestion to cure this?

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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 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

I can access the stack from the attic, is there any thing I can do from there?

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Originally Posted by DaveeR

I can access the stack from the attic, is there any thing I can do from there?

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Probably not, since the pipes are rubbing against a stud in the wall. Where's the sound the loudest? Cheers, Tom

I pulled off the baseboard behind my toilet and found the stack to be located in the wall about 16" from the back of the toilet towards the sink. Using a drywall saw I opened up a 6" wide by 16" high space to confirm the problem. The sole plate (2"x4" board that runs along the floor) was in contact with the stack pipe on the right side. I used a sawzall (carefully - at an angle to avoid cutting the stack) and removed the piece (a "cat's paw" works well to pop out the piece(s)). See picture. I just covered the area with some beadboard behing the toilet. Should've done this years ago - 10 minutes of work. If you would like a picture, I'd be glad to send you one. Email "[email protected]"

Complaint stated that noise was coming from the stack - not from the hot water line. I've explained one possible source of stack noise (sole plate) in a post from April 6, 2013. The PVC stack can make noise when it expands as hot water runs through it --- especially on a cold day.

Ivahotone...

Why did you post to a thread from 2009 in April 2013 and again today, Sept. 9, 2013? I guess I at least understand the post from April, but why the new post today?