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Thread: Water Heater thumping noise

  1. #1
    DIY Junior Member PJ Flocker's Avatar
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    Default Water Heater thumping noise

    I have had my (75 gal, new house) water htr for about 4 years and I have noticed a thumping noise (it is easy for me to hear because it is in the wall right beside my master toilet area) almost every time I use the master shower and when I run the hot water in one of the sinks. It sounds like the noise it is coming right from the hot water heater and not any pipes in the walls. My plumber nor any contractor has been able to figure out what it is. Any thoughts??

    Thx!! PJ

  2. #2
    Plumber patrick88's Avatar
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    Is it gas, oil, or elec...? Does it have and expansion tank on it? Do you have a pressure reducing valve on your main?
    I'm just starting to work with an old friend of mine to bring solar electric and hot water systems, wind turbines, Flex Fuel Boilers, batteries, hydroponic gardening, books, pellet grills and more. Also the parts for DIY installation.

  3. #3
    Commercial Plumber markts30's Avatar
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    Expanding pipe?
    Hot water running through water or waste pipe causing it to rub on framing members inside the wall - noise is amplified by the drywall surface...

  4. #4
    DIY Junior Member PJ Flocker's Avatar
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    Yes...sorry it is gas. I don't believe it has an expansion tank...how would I know? And, yes, we have a pressure reducing valve on the main...

    THX

  5. #5
    Master Plumber Dunbar Plumbing's Avatar
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    If you haven't drained the water heater yearly and it sounds like monkeys drumming whenever there's a quick shutoff of water....it is sediment bouncing around in the bottom of the tank.
    Read what the end of this sentence means.

  6. #6
    General Contractor Carpenter toolaholic's Avatar
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    Agree with Rugged ,Let's call it MUD JUMPING drain it with a hose for 5 minutes

  7. #7

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    I don't know what part of the country you're in, but here in Idaho, the water is very hard. Soon after installation, a gas water heater is likely to have a skin of lime on the bottom, and as it heats gas bubbles form under it, and it pops. It can sound like gunfire. It won't do any harm - except for the sound. It's much more prounounced as the heater gets older, and although draining may help, it may not solve the problem. Unless the heater has a hand-hole cleanout, which is a rarity in residential heaters, you're probably stuck with it.

    If your part of the country does not have hard water, it may be, as previously stated, flushable.

  8. #8
    General Contractor Carpenter toolaholic's Avatar
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    Thumbs up Thanks' Herk

    Had No idea , Here in N. Ca. We don't have that problem.

    Another VOTE to, " MAKE EM POST THEIR LOCAL. "

    Don't make Me break any more little fingers !!

  9. #9
    In the Trades Gary Swart's Avatar
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    This may or may not be the solution to the thumping problem, but if you have a pressure regulator valve, then you should install an expansion tank in the cold water supply line. When water heats, it expands and has to go somewhere. A PRV has a check built in that prevents the expanded water from being absorbed by the city main. This causes the pressure inside the water heater to rise rapidly and to a very high level. So high that it usually trips the TP valve on the tank. The expansion tank absorbs the expansed water.

  10. #10
    General Contractor Carpenter toolaholic's Avatar
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    Thumbs up

    Good point Gary,but He didn't mention the t p dumping!

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    I thought I'd read that a PRV when it gets worn some can sometimes make that noise under excessive pressure. Regardless, if you have a PRV, you must install an expansion tank...they go hand in glove, you have one, you should always have the other.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #12
    Moderator & Master Plumber hj's Avatar
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    Default thump

    Do you have a retrofit hot water circulating pump on the hot water outlet of the tank?

  13. #13
    DIY Junior Member PJ Flocker's Avatar
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    Default Thanks everybody!!

    Sorry...my location is Phx, AZ. So, as to the re-circ pump..I don't have on of those, although I wish I had one...it takes forever to get hot water to my kitchen. Anyway, I do have hard water where I live in Phx., but I have a soft water system since the house was built...
    Also, it doesn't happen after a quick shut off...usually after the hot water has been running for maybe 5 minutes or so...
    So, I think from all your comments my solution is to flush, check my TPV and the expansion tank...

    Thanks everyone!!!

    PJ

  14. #14
    Moderator & Master Plumber hj's Avatar
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    Default noise

    The noise could be the water meter sound being amplified by the water heater.

  15. #15

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    Quote Originally Posted by PJ Flocker View Post
    Sorry...my location is Phx, AZ.
    PJ

    Hey!

    I'm in Phx and have (maybe) the same issues in TWO houses. Ruud brand 40 gallon.

    No expansion tank, never used them before.

    When I turn on the cold water somewhere, the gas WH occaisionally makes a nice little pop. In the other house it's more of a BANG .

    Mine is not the rumbling sediment sound, just an pop or bang occaisionally

    Must be the heat here.
    Last edited by Alectrician; 10-31-2007 at 10:50 PM.

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