Noise from copper pipe in the attic

sweet_homeJune 9, 2010

We are doing some energy improvements in our house. The insulation in our attic was completely removed and attic air sealing work was completed today morning. Since today we have been noticing a noise(more like a thud noise) whenever we open the hot water in one of our bathrooms. This bathroom is the only place to which the pipe goes through the attic(rest of the house has plumbing through the crawl space) This happens only for the first time when we open the tap. We don't hear the noise if the tap is opened frequently after that. However, the noise is back if we wait for a long time and then open the tap again. My husband went up the attic to make sure that everything was ok with the pipe. He feels that the copper pipe is expanding and that's what is probably causing the noise as it is nailed to the stud. I am very confident that we are hearing this noise because something changed after the folks went up there for the air sealing. Otherwise we would have heard this noise all along and not just starting today. Could there be anything that might have been displaced? Are there any fittings around the copper pipe( that typically mask the expansion/contraction noise) that could have been accidentally moved or removed while walking over the pipes? Before I run about calling a plumber to come and take a look, wanted to check with the knowledgeable folks in this forum. Would really appreciate if folks can provide any pointers. Thanks!

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I should clarify that the noise is more like a banging/knocking noise(rather than a thud noise) and lasts for a few secs. The noise comes back if we open the tap after say an hour or so.

    Bookmark   June 10, 2010 at 12:31AM
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That is a symptom of water hammer. It can be reduced/ eliminated by making sure that the pipes are properly secured and a water hammer arrestor installed.

    Bookmark   June 10, 2010 at 1:18AM
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Thanks David. Can water hammer happen even while opening the tap? I had read about it earlier but was under the impression that it happens only when the water supply is cut off/closed. Is the water hammer arrestor something only a plumber can do or is it a DIY job for someone with basic plumbing knowledge?

Another possibility I didn't think of is it that currently there is no insulation in the attic. Is it possible that the expansion/contraction of the pipe is a lot more (because of the missing insulation) in turn making this more audible noise? My husband checked the pipe and it seems to be tightly secured.

    Bookmark   June 10, 2010 at 10:30AM
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It could - the pipes could vibrate for a few moments.

There are different types of water hammer arrestors available - ranging from a capped off section of pipe to screw on units you could purchase from Home Depot/ Lowes.

The pipes may be properly secured in the attic, but somewhere in wall cavity, something may have been shaken loose.

You could attach a screw on arrestor on the hot water supply line just below the sink and try turning on the hot water to see if there is any effect.

    Bookmark   June 19, 2010 at 1:35AM
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Hi, I just converted to gas from oil..I have a large 3 family with an old single pipe steam radiator system. The new boilers are around 82% efficient. It was installed in the summer, so I'm only now starting to work out the bugs!!
The main problem I'm having is trying to eliminate the noise (water hammering) associated with a steam radiator system. I have tried all the standard remedies related to this problem. I have drained and refilled the boilers several times, keeping the water level a little above half in the sight glass. I have made sure that each and every radiator is pitched towards the valve. I have insulated all the mains in the basement with 1000 degree fiberglass steam pipe insulation. I have even changed many of the vents at the radiators. While these actions have help significantly in reducing the water hammering noise! They have not totally eliminated them!

Any recommendations out there as to what more I can do to completely eliminate this problem?



    Bookmark   November 23, 2011 at 3:42AM
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