Noisy water pipes

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Posted by: from Calgary
2/23/2009 at 2:49:22 PM

I am the 2nd owner of a home that was built in 2005. I recently starting hearing rattling/knocking pipes on the following occassions:

1. Toilet (in basement) - immediately after the water fills the toilet tank and the water shuts off, I hear a couple of rattling noise - sounds like a couple of boards banging into each other. The noise is very short and only that one time, until the toilet is again flushed and the tank fills up. The noise is coming from inside the wall, behind the toilet, but in the room above the toilet. I do not have this problem with the other toilets in the house. The noise only started a few months ago. It was never a problem before.

2. Dishwasher - about halfway through its cycle, I would hear knocks - each knock is single, about 5 seconds between each knock, and the episode would last about 20 seconds or less. This noise only started this month.

- Do you think hammer arresters would solve my problems with the toilet and dishwasher?

- It has been suggested that there may be air bubbles in the pipes and that I should shut off the water valve that supplies water to the house, open all the faucets to drain the water out of the pipes, then leave the faucets slightly open, open the water valve to let some water in but only a 1/4 or 1/2 way, once all the faucets have water trickling out, shut off all the faucets and open the water valve all the way. Would you suggest this method? Any problems doing this method?

Any help you can provide is great appreciated.

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Date/Time2/26/2009 at 8:20:38 AM

Hi Pam- I don't know about the hammer arresters, but you could try whats already been suggested by shutting down the main. I find quite often the reason for the rattle is that the pipes are not fastened properly inside the walls. Where they pass through studs or blocking, the pipe may rattle against the wood when there is a change in pressure. Hot water pipes tend to expand when being used, and could cause a rattle. This appeared over time, so its taken that time for the pipe to possibly work itself loose. If its only 1 or 2 locations & all that would be required is a drywall repair, I'd try that. Fasten the pipes with the proper straps, small pieces of cedar shim could be tapped into holes where the pipe passes through the studs/blocking- they could be glued in place with a construction adhesive. Pipe wrap could also be used if the pipes are to close to the drywall.

Hopefully some of the other contractors on here will offer other advice to help you out. Take care, Pam.

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Abba's Service in Huntsville
Date/Time3/18/2009 at 10:53:58 PM

Hammer registers not a chance it sounds to me that when they built this home it was not done right at all I also commented on your fan problem If I am right you are the lady that is Calgary right! In fact you have my personal email already. I have heard this one before. and the problem you have is not that big of a problem but you will need to fix it one day in the future. You see they are supposed to fasten the pipes inside the wall so they don't move anytime there is some back pressure. It is just a couple of little clamps that hold them in place. Chances are the builder didn't use any when they did the piping. If you basement is unfinished Look up at the pipes in the ceiling under where they go through the joists get somebody to flush the toilet or use the dishwasher if you she the pipes shake that is your problem and chances are they will just a little. It is called pipe simmer!

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Blueprint Contracting in High River
Date/Time3/19/2009 at 1:38:10 AM

Pam, here in calgary we don't use clamps. What is required is plumbing straps, they get wraped around a pipe then screwed to a joist or framing member. This is to ocurr every 4 ft. I'm thinking this is your problem it does get missed a lot in new home building and the plumbing inspectors do not pick up on it all the time.

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Date/Time1/25/2011 at 11:03:42 AM

As a service plumber of 18 years. The problem you are having is pretty common. I would suggest to replace the fill valve in the toilet that is making the noise and install a shock arrestor under neath the kitchen cabinet to your dishwasher. This will solve your problem. Also purchase a hosebib water guage and test your house pressure. Normal static house pressure should be at 65psi. Anything higher will cause abnormal piper banging when the valves turn off after use

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Graeme from Watermark Plumbing in Burnaby
Date/Time1/25/2011 at 2:16:23 PM

As a Journeyman service plumber from Vancouver, I agree with Doug's comments. Before you start cutting down dry wall Check Your House Pressure!

You can buy a gauge from Home Depot and attach it to your washing machine's cold shut off valve. If the pressure is much higher than 65 PSI static you may need a new Pressure Reducing Valve for your house.

Yes, you should also have Water Hammer Arrestors for your dishwasher and your washing machine. Dishwashers have Solenoid Valves which cause water to shut off abruptly (similar to slamming on the brakes in your car) and this causes pipes to rattle. Loose pipes can also cause noise but address these other issues before opening up walls to check strapping.

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