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Vibrating pipes

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  • Vibrating pipes

    I'm a new construction plumber for the most part, but I get the very odd "service" derived call from family friends and such. Only had a few as I'm still an apprentice, and I'm wondering if you guys can maybe enlighten me potentially as to what this is.

    I notice in the field that sometimes when you crack a ball valve or supply stop you might get a little bit of a vibration in the pipes, sort of a "shudder" but when the valve fully opens it goes away and the flow is normal. Well these people have a 3 floor house, with basement suite tenants. There are 2 bathrooms along the backwall, one on the 3rd floor, and one on the 1st floor, with a kitchen sink on the 2nd floor. I am guessing because they all share a common wall, that they probably share common supply pipes as well, going up/down the wall (didn't look, but that sounds the most likely to me). The house is a 35-ish year old house with copper pipes. The stops are chroem plated, compression stops with escutchion plates, the usual. The owner says he noticed the problem right around when they installed a newer toilet a few years ago down stairs but it only really got worse recently. It's hard to describe, but basically if they flush the toilet on the 3rd floor sometimes you wil get a solid vibration in the pipes, in the walls, almost like a hum. And the Hum can last for several minutes. I think it happens when they use the toilet on the bottom floor in the basement suite too. But he also said if they hum is occurring, and he turns on the water on the 2nd floor kitchen sink that the hum stops. They tried to replicate it, finally they did, but I don't want to start ripping apart/replacing things until I have a better idea of what it could potentially be. I figured it could be debris in the lines or something like that. I don't think it's water hammer related as it only happened recently. But it is definately noticeable.

    Any thoughts?

    Again the top floor has a toilet, bathtub/shower & lav, the bottom floor has the same, and the 2nd floor is a kitchen sink, again all with a common wall which again I'm guessing water supplied goes up/down. The sound definately comes from this common/back wall and it is throughout the entire wall from the top floor to the bottom. Also, I would like to add that if you turn on the shower to the top floor, the flow to the toilet when it fills up is very very very slow, which to me says maybe the bathroom only has a 1/2" supply and the water is taking the shortest/easiest route out the shower but when you shut the shower off the toilet fills up like normal. Don't know if this has any bearing on the problem potentially.
    Last edited by Scott K; 11-05-2006, 09:47 PM.

  • #2
    Somewhere in that description you seemed to have answered your own question. Sounds like a problem with the valve in one of the commodes, possibly two.

    An improperly opening valve can create a stutter. Sometimes a high frequency stutter. This stutter is a vibration that will travel inside pipes for a looooooooooooooong way, because the water won't compress. Commodes have small valves that have small orifices. Water rushing past an edge in this small orifice can create this vibration.

    Find the commodes(s) that are doing this and replace the valves. This is the cheap place to start. It's probably the valve in the commode tank, but it could be the angle stop if it is only cracked and not full open. It's unlikely that it's in the wall.

    I awoke one night about a year ago to the sound of a wailing pipe. It was all the pipes in my entire house. I checked everything and could find no problem. The sound lasted about an hour. The next day the city was working on the water main a block away. I'm assuming that's where the vibration came from. My house is the end of the cul-de-sac. I built this house in 1984. That was the only time it ever happened so I must assume it was the city line.


    • #3
      What Big Thom said.

      If you think about it water will not compress the way air will. That means when you get a chatter or hum in a valve the entire system will be effected by the action at the valve. The way to find the offending apparatus is to operate each one until you find the one that causes the "hum".

      "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

      I never lost a cent on the jobs I didn't get!


      • #4
        Friction loss and water velocity as factors determining the size of water supply. Friction loss is the rubbing action of the moving water against the interior sides of the pipe. The length of the pipe increases the friction loss proportionally.
        For example, if the pipe size is doubled, the friction loss is doubled as well. If the interior of the pipe corrodes and becomes rough, the friction loss increases significantly. Water velocity is a measure of how fast water flows through the piping. Friction of water is proportional to the square of the velocity. Average water velocity equals 8 feet per second under normal conditions. Increased water velocity causes excessive wear, corrosion, and water hammer – a knocking sound in water pipes caused by a sudden change in pressure after a faucet or water valve shuts off.
        Both friction loss and water velocity should be considered when sizing water supply pipes.
        With that said, I would look at the size of the supply lines.

        Minimum sizes of water supply pipe
        Selection of water supply piping is restricted to the following minimum sizes:
        1) ¾-inch size pipe – for any building from the street to the water meter;
        2) ¾-inch size pipe – for the first section of water supply piping within the building;
        3) ¾-inch size pipe – to a sill cock or lawn faucet;
        4) ¾-inch size pipe – from cold water supply to a water heater;
        5) ¾-inch size pipe – for the first section of hot water piping on the outlet side of a
        water heater;
        6) no less than ½-inch size pipe – for concealed piping;
        7) ½-inch size pipe – for no more than three fixtures in one bathroom or house;
        8) ½-inch size pipe – for fixture branch piping;
        9) ⅜ or ¼-inch size pipe – for individual fixture water supply piping that is not
        concealed and does not exceed 30 inches in length.

        The factors that determine the sizing of water supply piping
        In order for the plumbing fixtures and appliances to operate properly the building
        water supply system must provide sufficient potable water. The following five
        factors determine the sizing of water supply piping:
        1) Available pressure – usually between 45-60 psi; should not exceed 80 psi.
        2) Demand – also called flow rate; the volume of water in gallons each fixture
        and appliance uses per minute.
        3) Length of piping – causes the pressure loss due to friction.
        4) Height of the building – causes the pressure loss due to the height the
        water must flow.
        5) Flow pressure required at the top floor – minimum flow pressure required
        for a fixture or appliance to function properly; varies from 8 to 25 psi.

        Minimum sizes of fixture water supply pipe
        Selection of fixture water supply piping is restricted to the following minimum sizes:
        1) Bathtubs – ½ -inch size pipe;
        2) Bidets – ⅜-inch size pipe;
        3) Combination sink and tray – ½ -inch size pipe;
        4) Dishwasher – ½ -inch size pipe;
        5) Drinking fountain – ⅜-inch size pipe;
        6) Kitchen sink – ½ -inch size pipe;
        7) Laundry – ½-inch size pipe;
        8) Lavatory – ⅜-inch size pipe;
        9) Shower – ½-inch size pipe;
        10) Flushing rim sink – ¾-inch size pipe;
        11) Service sink – ½-inch size pipe;
        12) Water closet with flush tank – ⅜-inch size pipe;
        13) Water closet with flush valve – ½-inch size pipe;
        14) One piece water closet – ½-inch size pipe;
        15) Urinal with flush tank – ½-inch size pipe;
        16) Urinal with flush valve – ¾-inch size pipe;
        17) Hose bibs – ½-inch size pipe;
        18) Wall hydrant – ½-inch size pipe.

        hope that helps?
        Last edited by All Clear Sewer; 11-06-2006, 12:33 PM.


        • #5
          All Clear. You're making this way to complicated. The initial thread says the noise in this 35 year old house started about 2 years ago when a commode was replaced. Now I'm guessing that the plumber didn't replace all the water pipes in the house then get everything patched while the homeowners back was turned, so more than likely the problem isn't the pipes.

          By the way, you're driving down the highway on your regular route home and one day your service truck starts shaking. Do you replace the highway or do you first check the balance on your tires?


          • #6
            Big Thom seems on the ball to me. I'm also with you on All Clear's comment.

            All Clear: water piping should be based on distance, pressure, and fixture units. It should not be based on "1st section", "to the water heater", etc.
            the dog


            • #7
              I`m sure I`m making this way to complicated as I`m working on my masters from an apprentice view point. I own an old Victorian House that I snuck all the new plumbing in.I also have the same problem from the second floor bath room hot side of the supply. I went with 3/4 CPVC thinking I could flush the water closet while taking a bath in the old claws foot tub. Now when you run the hot water we get some slight hammering because I went over board on the water supply to the tub. there are many factors that cause Pipe Hammering but most of the time it is some one like myself thinking we have to have more supply then we really need. Yes it can be a valve but you have to look beyond that some times.

              BTW... I`m new here and dont know better


              • #8
                All Clear,

                I believe you may have missed the original posters post but he is not having an issue with a water hammer he is having an issue with a hum. A water hammer would be more of a bang or series of bangs.


                BTW: Welcome to the Forum.
                "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                I never lost a cent on the jobs I didn't get!


                • #9

                  I think you already answered your question. Didn't the noise come from changing the toilet? If yes, try changing the water stop and be sure the new one is a ball balve type. Then change the connecting tube. Use something a good bit different from what you currently have and give it a week or so. If it still sings, then do a replacement of everything you haven't replaced related to that toilet.

                  Do you have a water pressure gauge with a garden hose adaptor? If yes, measure the pressure with everything off. If you are above 60 PSI you might want to think about installing a pressure regulator and a simple filter in front of it.

                  Good luck as I bet at times the noise really bothers people there.


                  • #10
                    Checking the water pressure is a must but I don't believe it will be the stop or the supply which is causing the problem. Typical the cause is a bad diaphragm or o-ring which is allowing a stem to vibrate. After verifying the pressure is below allowable limits I would start by checking the ballcocks. If it is not in the ballcocks I would check the washers in the regulator. If you still have not found the hum just keep checking the rest of the faucets and valves one at a time. It helps if you have someone else operate the apparatuses while you search for the hum.

                    "Somewhere a Village is Missing Twelve Idiots!" - Casey Anthony

                    I never lost a cent on the jobs I didn't get!


                    • #11
                      Originally posted by ToUtahNow View Post
                      All Clear,

                      BTW: Welcome to the Forum.
                      Thank you
                      I hope to learn a thing or two here so beat me up please!!!!!
                      It will only better me in my quest for being a better plumber!