What Else To Do Now–PVC Pipe Noise

[Gabbi]

Hello. As I’ve written in the past on here (and appreciate all the helpful responses!). I have a very thin wall in the house that is probably 6 inches thick, 12 feet high. The wall houses the drain pipes (PVC material) from bath upstairs. When shower is used, the pipe makes frequent, short loud bangs, and when sink is used, it does too–though it lasts longer even past when sink is off. Believe it is thermal expansion, insulated wall in lieu of knocking big holes to put sleeve on pipe. No luck, still does it. Now the wall is full of white dusty insulation—-holes haven’t been plugged, still have small access window to shower drain pipe (main culprit), anything I can do? The drain pipe is about as thick as the wall is, so the insulation itself provides very little cushion between pipe and wall. Thanks

[turdchaser]

I’m pretty sure that the noise you are describing is not from the drain lines but from the water supply lines instead. First and foremost check the water level in the tanks of your toilets make sure the fill valve is fully shutting off 1″ below the overflow tube. If this is correct then two other things should be done. Have water hammer arrestors installed on the lines creating the problem and have the water heater flushed of sediment buildup. If the problem still exist the lines are very loose in the walls and you will need to open the walls and secure the lines properly to eliminate movement. Also please let us know how it turns out.

» This message has been edited by turdchaser on 16 January 2004

[Less500]

Thanks for the response. Actually, I think we eliminated water hammer. Put on arresters, but nothing has changed. The water supply lines serving that bath on 2nd floor run through the floor, or what would be the ceiling of the first floor. The noise appears to be clearly coming from inside the wall, which only houses those drain pipes. It’s definitely not toilet—it’s the shower, which stops when shower stops, and separately, the sink, which begins when sink is on, lasts a little while longer. Many here thought it was the PVC pipe expanding, which seemed logical, and the pipe is about as fat as the wall is thick, so it could be knocking into wall??

[DUNBAR]

You need to trace that drain line to where it is in contact with a wood surface in the wall.

Thermal expansion of the plastic piping is “ticking” across the area where there is movement against the two objects.

The only way your going to find it is to start opening the wall where it is either braced, or passes through the joist area. Access directly behind shower is useless unless you can visibly see the piping touching the wood where it is in contact with.

When you do find it……you are going to have to cut out or chisel the wood out farther away from the piping to allow free movement for thermal expansion.

If your not willing to open the walls, then you will have to deal with the sound it makes.

[turdchaser]

Ok, your convinced it is the drain, lets deal with that and verify that first. If it is the drain the noise would occur when the water is flowing down the drain. Plug the sink fill it with water if you hear noise while it is filling but plugged it is the supply lines. Next turn the water off wait a few seconds and then drain it. If the noise now occurs and did not before it is the drain. Please do this with the shower as well and let us know for sure which it is. If you have already performed these task in the past I apologize for being redundant.

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