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Water hammer or loose pipes?

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  • Water hammer or loose pipes?

    Sorry if this question has been asked many times. I searched before I posted (which did help a little) but I'm not sure what my problem is. Sorry if this is a little long but I want to provide some background.

    Over the last year I have replaced my old washing machine with a new front load model, a toilet on the main floor powder room and a complete reno of my master bathroom. All the fixtures seem to be run off the same plumbing lines. Or at least they are connected. They are in the same general area of the house.

    Things went smoothly except for the washing machine replacement. The 25 yr old cold water shut off valve was dripping a little so I decided to replace both the hot and cold with the newer lever type shut off valves. While removing the old cold valve the copper pipe became really loose. Thought the strapping just came loose. Put on new valves, turn on the water at the main and flooded the basement. The loose pipe was because of a poorly fit elbow joint done when the house was built 25 years ago - the solder was the only thing holding it together and when I put pressure on the pipe by removing the old valve it came loose. Anyway, i fixed that, checked for leaks and re drywalled the ceiling in the basement.

    Now I've noticed the pipes banging whenever the water is shut off in any of the renovated areas (master bath shower, powder room toilet, washing machine in laundry room). The banging is isolated to one section of the house (4 ft x 4ft section over my living room). It's been going on for 3 months. Sounds like a loose pipe rattling but I'm worried about water hammer.

    The banging is only when something is shut off (after a toilet flush, sink faucet is turned off, shower turned off, bath tub faucet turned off etc). Never when water is turned on or when water is running.

    I've tried to get the air out of the pipes by turning off the main, opening all the fixtures, flushing toilets and turning on the main again. This didn't help. Banging is still there.

    Before I start ripping open drywall and my living room ceiling to look at the pipes I'm wondering if it's worth getting a plumber in to check it out?

    With so many new fixtures it's hard for me to narrow it down to one specific cause.

    What do you guys think? Appreciate any advice

  • #2
    Re: Water hammer or loose pipes?

    its a combination of both loose pipes and water hammer. The water hammer is ratting the loose pipes. If you redid some of the copper piping and removed the air chambers this can cause an issue. The other problem could be that you did not restrap the pipes properly.

    In lots of homes I been in that put in the the front load washers , they tend to have very fast acting solenoid valves which causes pretty severe water hammer. I put in the washing machine water hammer arresters and problem solved.

    In cases where other fixtures are causing the water hammer, and there is known air chambers in the system. I shut the main off and drain down the whole system opening every fixture in the home. Once all drained down, I turn off all the fixtures, and slowly turn the main back on. Once pressurized I go to the furthest fixture and bleed the air out of the lines and work my way back to the basement. This helps get air back in the air chambers and 98% of the time it solves the problem.
    Ron Hasil Lic #058-160417
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    A-Archer Sewer & Plumbing specializing in:
    Tankless Water Heaters | Drain and Sewer Cleaning
    Sump and Ejector Pumps | Backflow RPZ Testing


    • #3
      Re: Water hammer or loose pipes?

      Thx Ron. I installed the arresters on the washing machine lines. Any other fixtures I should think of putting the arresters on? Shower valves, etc? It would mean cutting into drywall but that is cheap compared to plumbing issues.

      I guess I'll shut off the main and drain the whole system again to see if there is any improvement.


      • #4
        Re: Water hammer or loose pipes?

        Unlike air water cannot be compressed so the entire water system becomes a single conduit of the hammer. The fact that all of your fixtures cause a problem tells me you have a loose pipe somewhere. I would also check the water pressure to make sure that is not making it worse.

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

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