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    d4nnyb0y02's Avatar
    d4nnyb0y02 Posts: 8, Reputation: 1
    New Member
     
    #1

    Feb 8, 2010, 09:16 PM
    Why does the PVC drain pipe in my wall knock whenever draining hot water?
    Trust me, it's not the copper. It only does it when things are draining. Like, when the dishwasher drains it's hot water. Or, if I fill a sink with hot water, and then pull the plug. A little while after the drain begins to have hot water flow down it... it begins to knock inside the wall. I have a general idea of where it is. Any idea why this would be happening, what he dangers of letting it go on, and if there is an easy fix for it?

    I have only owned the house since November, and it has done it ever since we owned it. I know about expanding copper, and water hammer. Trust me, this is not that.
    Milo Dolezal's Avatar
    Milo Dolezal Posts: 7,192, Reputation: 523
    Plumbing Expert
     
    #2

    Feb 9, 2010, 07:34 AM

    You are most likely hearing pipe expending in the wall. It may be that your drain is too tight against framing producing friction noise when hot water is present.
    d4nnyb0y02's Avatar
    d4nnyb0y02 Posts: 8, Reputation: 1
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    #3

    Feb 9, 2010, 11:45 AM
    Quote Originally Posted by Milo Dolezal View Post
    You are most likely hearing pipe expending in the wall. It may be that your drain is too tight against framing producing friction noise when hot water is present.
    Could this present a greater problem if unaddressed?
    speedball1's Avatar
    speedball1 Posts: 29,301, Reputation: 1939
    Eternal Plumber
     
    #4

    Feb 9, 2010, 12:50 PM

    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. Good luck and thank you for rating my answer. Tom
    Milo Dolezal's Avatar
    Milo Dolezal Posts: 7,192, Reputation: 523
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    #5

    Feb 10, 2010, 12:35 AM
    Quote Originally Posted by d4nnyb0y02 View Post
    Could this present a greater problem if unaddressed?
    I don't think it should present a problem. PVC and ABS drains are tested before approved by local Plumbing Codes. Therefore I would not worry too much about them...
    GodlessBastard's Avatar
    GodlessBastard Posts: 1, Reputation: 1
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    #6

    Mar 10, 2010, 08:36 AM
    It has recently come to my attention that you are a deeply disturbed, religiously deluded person. Only a moron would believe that god is real, and as such I am genuinely concerned about your intellectual well-being. It is of critical importance that you know about GodlessBastard.com. Do you want to spend the rest of your pathetic existence wallowing in clinical delusion, cowardice, weakness, gullibility, and general intellectual inferiority? Well, you’re doomed to do so unless someone shakes coherence into your malfunctioning gray matter. And I’m here to help do just that.

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