noise (banging) coming from water heater

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by lwolff, Dec 12, 2005.

  1. lwolff

    lwolff New Member

    Dec 12, 2005
    I have a noisy water heater. It's only 3 years old, 75 gallon, natural gas. The owners manual diagnoses mineral deposits in the bottom of the tank and suggests draining it regularly.

    I drained the tank (as suggested) but the banging continues. Is there a better way to clean out the tank other than just draining it?
  2. Cass

    Cass Plumber

    Nov 12, 2005
    At this point there is no practical way to remove the deposits. Now or the next time you replace the heater install a softner and this should prevent that from happening to the new one.
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  4. dubldare

    dubldare Plumber/Gasfitter

    Sep 14, 2005
    Generally, I will 'flush' tanks. I call it flushing because I leave the cold water on to the heater while draining.

    The incoming water will put the sediments into suspension and carry them out of the drain valve under pressure. Turning the cold shut-off on and off rapidly also helps quite a bit. Kinking the hose does the same thing.
  5. Bob NH

    Bob NH In the Trades

    Oct 20, 2005
    New Hampshire
    Clean The Heater

    A 3 year old gas water heater is worth saving. Calcium deposits are caused by the fact that calcium salt becomes less soluble as the water gets hotter, so it deposits on the heat transfer surface. The banging is caused by the fact that small areas get so hot that they produce steam bubbles even under the pressure in the heater.

    You can try the "Flushing" process described in previous posts. If that doesn't work you may want to try the "teakettle" process. If you put some acid (vinegar) in a teakettle and simmer it a while the calcium deposits will dissolve.

    I'm an engineer who would consider it an adventure to pump dilute muriatic acid through my gas water heater, but that is not a challenge that everyone would welcome.

    I found a site where Gary Slusser in Dec 2000 described the pumped acid process for cleaning a tankless coil. Maybe he can suggest the acid concentration for a water heater to save the need for experimentation.
  6. Cass

    Cass Plumber

    Nov 12, 2005
    While you can use muriatic acid it's use is not recomended as it will etch the lining of the heater and most likely reduce the life expectancy of the heater. If 3 years of use created the situation this would indicate water that is quite hard. Adding a softner will stop any additional build up and may slowly reduce the amount of sediment that is there now.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Flushing will seldom stop the noise because it is often caused by "nodes" that have built up on the center flue pipe. The nodes allow water in, and then the hot flue gases heat it to the point it becomes steam and is forced out of the node where it condenses upon contact with the water and creates a mini-explosion as the excess eneregy is expended.
  8. plumber1

    plumber1 Plumber

    Aug 7, 2005

    I also found that its a waste of time to drain and flush noisy water heaters.
  9. Master Plumber Mark

    Master Plumber Mark Master Plumber

    Feb 6, 2005
    Sensitivity be caring and loving to a
    indianapolis indiana - land of the free, home of
    do what dubldare said

    try doing what that fellow told you to do....

    its ease and can take care of the problem without too much

    AI dont know what the "nodes " are that Hi mentioned, but have
    had fairly good luck with this next approach...

    the next approach is to turn off the water to the heater, turn the
    gas to piolit

    relieve the pressure then take the drain valve totally out of the unit..

    The water willl come out of the hole and make a mess,

    make yourself a "mineral scraper" out of a piece of 3/8 copper

    about 30 inches long

    flatten down one end about 2 inches worth then bend it and make

    an L

    ...Reach into the hole and simply scrape the bottom of the tank with your

    new psecial tool........

    It will even get to those hard to reach spots on the back side of the chimmney.....

    as the water is comming out , so will the deposits.....

    of course its going to make a hell of a mess on the floor

    but a guy has got to do what you got to do

    and I hope its
    in an unfinished area of your basement--garage

    It will silence those demons, for a while...maybe 1 year..

    then do it again...
    Last edited: Dec 13, 2005
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