Pipes making noises


Old 08-09-15, 04:16 PM
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Pipes making noises

I have a one-story house, with copper pipes for plumbing. There is a crawl space. There is a gas hot-water tank with one of those canisters beside it. The canister appears to be on the cold water line.

The master bathroom is the farthest room from the hot water tank. When I run the cold water in the sink there, then shut if off, it sounds like the pipes make a banging sound for a couple of seconds. The same thing happens with the hot water tap. To a lesser degree, the same thing happens in the hall bathroom, which is right beside the master bathroom. The problem does not happen with the tap for the kitchen sink. Occasionally, the shaking sound can be heard when no one runs any water. I have lived in this house since 2002, and this problem just started to happen this year.

I have read that this problem can be caused by water filling up the air chamber. Apparently after a long time the air in the chamber can dissolve into the water, leaving the chamber filled with water. I understand that the air chamber is just a short section of pipe extending up from another pipe and coming to a dead end.

I have heard that this problem can be solved by shutting off the valve out by the curb, and then opening up one of the faucets outside the house, and then shutting the faucet off, then turning the valve at the curb back on. I tried that, and after I was done, the problem persisted. Then I tried doing it a little differently, by leaving the kitchen tap on, then repeating the entire procedure described above. The result was the same. After all that, the pipes still made the same sound after running the tap in the master bathroom and then shutting it off.

After I did all the stuff I have described, I saw an article on the web that said air chambers are pretty much useless and building codes don't even recognize them as being useful for controlling water hammer any more.

What is the problem here? Does it have something to do with that canister beside the hot water tank? Is it something I can fix myself? If I do nothing, will the shaking of the pipe do any damage?

Last edited by Northwest_Home; 08-09-15 at 05:34 PM.
Old 08-09-15, 05:32 PM
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It sounds like you have water hammer. When you open a faucet there is a lot of water in motion. If you quickly close a faucet all that moving mass suddenly comes to a stop which can cause pipes to flex and bang. The tank next to your water heater does not address or solve this phenomena.

Not all homes and I'd even say most don't have water hammer arrestors which are the things you're talking about. They are often buried in the wall so it can be difficult/impossible to tell if you have them. Restoring the cushioning bubble of air can be difficult as you've found out (if you have the arrestors). I've found that you need to drain your pipes. So, do what you did before by shutting off the water main. Then open the faucets inside the house. Then the key is a faucet or drain somewhere low to provide a place for the water to drain. If it works it can take a while and you have to be mindful of your water heater. It's safest to turn off the power or gas to it.... In the end the odds are that your home does not have the devices you are trying to "restore".

Long ago all sinks and tubs had several knobs. Turning off the water required the turn of a knob or two which could only be done so fast. The slowness of turning the knob is enough to prevent the water hammer noise. Then comes modern single handle faucets where a quick flick can slam the valve shut. So, worst case just get in the habit of closing faucets more slowly.

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