Return to the Plumbing Forum | Post a Follow-Up

"Moaning" pipes in new construction?

Posted by SusanCF (My Page) on
Wed, Nov 14, 12 at 2:59

Ever since we moved back into our house after extensively remodeling it, including almost all new plumbing, we've noticed (especially at night, when other sounds are low), a frequent "moaning" that lasts a second or two at a time. It can be quite intrusive when the house is quiet. We haven't been able to identify the source or a trigger for the sound, but our best guess is that is has something to do with the water pipes. For the record, we have tankless water heaters (two) serving the house and a small apartment. The sound occurs even sometimes when there is no obvious water use going on, but we just don't know what else could be causing it.

We are quite surprised to have such a problem in a house with new plumbing. Is this a common/known problem in new construction? Is there something we can do to fix it, hopefully without tearing holes in the new walls? Thanks for any ideas.

Follow-Up Postings:

RE: "Moaning" pipes in new construction?

Thermal expansion of ductwork in the house can cause a moaning sound when the furnace kicks on and starts putting out warm air. This can happen when the duct is not properly mounted and is rubbing against a fixed structure or object. Isolating the exact location of the problem can be frustrating because you have to be looking at the right time, insulation can hide the problem location and the sound can echo through a large section of ducting.

RE: "Moaning" pipes in new construction?

Water pipes change size when the line is used, then slowly shrink back as they cool to ambient.

Hot water pipes are usually worse since the temperature swing is larger than the cold water line.

It takes a while for everything to come ot ambient since the water in the pipe AND the pipe both need to adjust their temperature.

'Moaning' type noises are often a pipe rubbing on a hole through a wood structural member.
Sharper noises can be the pipe stick/slipping over it hangers (especially plastic pipes since plastic has a higher coefficient of thermal expansion than metal pipes).

All you may need is a few turns of even paper (I prefer wax paper) where the pipe goes through a structural member or a holder.

Wrap it around the pipe about two turns than slide it into position so it is between the pipe and anything it is touching tightly or resting on.

It can be a rel PITA on finished work with pipes inside finished walls.

RE: "Moaning" pipes in new construction?

You don't live in Amityville, right?? ;)

RE: "Moaning" pipes in new construction?

Thanks for those replies. Nope, not Amityville :-)

It can't be the furnace, because this happens whether or not the furnace is in use. It even SEEMS to happen whether or not the water is in use, but perhaps the tankless heaters have their own ideas about when to turn on and off. The thing is, some days it seems to go on and on and others days we don't notice it, making it hard to bring in a professional to maybe deal with it.

Annoying to think that the builders didn't make sure to install the pipes in such a way as to avoid this problem (I hear it as I type this!) Well, maybe someday we'll stake out the basement and try to track down the locations ... hhough leaving the basement door open doesn't seem to make the sound any louder.

RE: "Moaning" pipes in new construction?

Water lines near duct-work or hydronic lines move as the air temperature around them changes.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here