banging pipes

[Rick Handel]

Hi,

I'm a first time homeowner who doesn't know jack about plumbing. When the hot water is run in either upstairs shower or the upstairs sinks, there is a rhythmic banging sound from a pipe in the wall. It occurs maybe every ten seconds or so. It then occurs maybe 3 or 4 times after the water has been shut off over maybe a 30 minute period. After hunting around on the net and in usenet archives, I've tried the following with no fix to the problem:

1) Turn off the water main, drain the pipes, and turn the water main back on.

2) Hot water heater is not super old (1998). I checked the thermostat on the hot water heater and it is set around 125 degrees. I also drained it to check for sediment, but the water that came out was very clear.

That about exhausts my knowledge of plumbing related to this problem. Other than the next step (calling a plumber) are there any other basic steps I can try?

Thanks, Rick

[3GCPO]

that means there is NO "air gap chamber" in the plumbing to the shower. call in a plumber to install them.

[Speedy Jim]

As the hot water runs thru the pipe, the pipe heats and expands (lengthwise). Every hole in wood framing it goes thru or metal clamp around the pipe is an opportunity for the pipe to "stick" and then suddenly break loose. After the water is shut off, the pipe cools and moves back again.

No fix except to find where it is hanging up and modify the mounting/clearance.

Jim

[Joseph Meehan]

From your description it is not water hammer (the problem draining the pipes would fix) but then doing the fix is free and will not hurt.

It sounds like the expansion problem and for that you need to gain access to the pipes and fix the points where they are getting stuck as they expand and contract. More of an annoyance than a problem. It can be a real problem to fix after the home is done if the problem is inside an inaccessible area like a wall.

[Rick Handel]

Thanks to everybody who responded. It's definitely in a wall because I can hear the place in the wall where the banging noise is coming from. Is this something that may damage the pipe leading to a leak over time? If not, the noise is not that bad. I'm more worried about a possible leak down the road than the banging sound itself.

Thanks again (to everybody),

Rick

[Toller]

I had the same problem a couple years ago. When I removed the ceiling tiles I found the pipes were almost entirely unsupported, so I figured that was the problem. After I put in supports, the banging got much worse. I replaced the supports with ones that let the pipes move, and opened up all the framing, as per the advice I got here. I was able to get the banging reduced to a tolerable level, but nothing I did actually got rid of it.

I hope you have better luck than I had.

[Michael Baugh]

My advice is to bypass that section in the wall. Unlikely that it really needs any supports, but someone probably secured it very well to a stud, and now it tries to move relative to those hangers. You'll continue to think about that metal-on-metal sliding contact, you'll find yourself waking up in the middle of the night thinking about it. Give yourself time to learn the necessary skills, then do it. You've probably got plenty of time. Unless one of the hangers was put in a bit sideways. Naah, not likely.

[Rick Handel]

LOL!

[AJScott]

I'm going to guess that you have copper pipes. If they were PVC, you'd have some really serious problems ;)

Seriously, tho, I'm also a homeowner who like you doesn't know a lot of jack about a lot of things, but something occurs to me as perhaps a possibility to explore: The fact that the banging occurs and continues after you shut off the hot water *may* indicate that the pipe is cooling faster than you'd like it to once you shut off the hot water flow, and that the banging is the product of this. Stuff that cools faster than nature says it should tends to be really noisy (ever pour cold water on a really hot pan as opposed to a warm pan?). Hence, a question to pose to a qualified plumber would be whether going to a larger-diameter copper pipe might eliminate this simply because by doing this, you would theoretically have more pipe cooling at a slower and possibly more uniform rate.

Otherwise, perhaps you might first try dialing down the temp setting on the hot water heater to a slightly lower setting, say maybe to somewhere around 105-110? The pipes get less hot and threfore will have less of a cooling gap to jump. Doing that might not eliminate the banging completely, but it might quiet it down to a more reasonbale volume level you can live with.

But if none of this is the solution, you can rest easy knwoing that on the bright side, all that pipe banging going on isn't harmful to children and other living things.

AJS

[Joseph Meehan]

I have never heard of a pipe being damaged because of this, but it is possible. Damage to your sanity is another thing.

[Rick Handel]

Yes, copper. :)

I'll try it, as long as it doesn't mean I will freeze my ass off. :)

[barry martin]

Rick:

RH> Thanks to everybody who responded. It's definitely in a wall because I can RH> hear the place in the wall where the banging noise is coming from. Is this RH> something that may damage the pipe leading to a leak over time? If not, th

RH> noise is not that bad. I'm more worried about a possible leak down the roa

RH> than the banging sound itself.

I would say to stabilize the pipe. When the pipe moves causing it to hit the wall/whatever, the pipe is flexing somewhat. Flexing will stress the weakest portion, probably a joint: leak!

- ¯ barry.martinþATþthesafebbs.zeppole.com ®

• I  this Tagline.

[Sue]

Maybe some chick getting it good

Sue

[Ilv2sl]

I've hadm banging pipe noise 2 times,and both were different problems. I problem was in the steam heating system. Every now and then, especially when we kept the thermostat low in the winter, the pipes would bank, like they were going tom fall apart. The problem was that when one of the pipes was installed, it had a low spot, that prevented thewater to return to the boiler, and whenn the heat came on again, it would boil the water at the "trap" and it would bang like he.. Re plumbing to eliminate the low spot cured it.

The other banging problem in the samehouse, was when the hot water was shut off, the pipes would bang. The hot water piping had, what I guess would be called a damper, in it. In the hot water pipe leaving the water heater, there was a tee installed, with a 3/8" piece of copper tubing, coming ogg it. This was a coil of tubing, rising from the Tee, about 6", and the end had a screw in it. The cure was to drain the system, and open the screw, to let all the water out of the coil, and put the screw back in. Then turn the water back on. The air in the tubing, acted like a shock absorber. Hope this helps.