Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

water hammer

ryan_2 Member Posts: 1
have 2 twinned 30gallon hot water storage tanks,heated by boiler loop.problem is when using hot water from faucets,shower i get very loud water hammer, not when turning it off but while runing for the first 20-30 seconds.i installed a properly sized thermal exspansion tank and hammer arrestor on the domestic outlet of the storage tanks.also because of high city water press. i insatlled a press. regulator on the main set for 65psi. original press about 120psi.have not had any luck stopping the hammer.could use some expert advice. thanks


  • Bill_14
    Bill_14 Member Posts: 345
    Water Hammer

    Do you have an air shock at the fixture? Is your pipe supplying this fixture properly anchored or are your hangers installed correctly? Is there a valve in the line?

    Bill Russell
  • Bob Gagnon plumbing and heating
    loose washer

    it's probably a loose washer in one of the shutoffs. bob
    To learn more about this professional, click here to visit their ad in Find A Contractor.
  • kevin
    kevin Member Posts: 420
    I agree w/ Bob.

    It it a Symmons ? I have had problems w/ washers and hammering noise.
  • Big Ed
    Big Ed Member Posts: 1,117
    I agree with bob...

    Sounds like a broken bib screw and a loose washer.............. But! But!........Remove the thermal expansion tank and make sure the tank's charge matches the incomming water pressure . Reminds me of this job years back , after a pile of service ticket's that was the solution to the problem. ......
  • Mark Eatherton1
    Mark Eatherton1 Member Posts: 2,542
    Passing bad checks...

    IF it has a circ return, and IF it has a swing check in a down flow position, I HAVE seen this scenario hammer. Water starts flowing in correct direction, and if the pump is on, it's OK. But as soon as the circ pump shuts off WHAMO. Water hammer. I've even seen it happen with the pump off.

    Just when you think you've seen everything there is to see, ya find out you ain't seen squat...

    Another question for you Ryan, does the water temperature or pressure change at the shower head when it hammers?


    To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"
  • Canuck
    Canuck Member Posts: 57
    I agree with all - but

    see if your PRV isn't faulty as well. If you're using something smaller than a Watts U5B there may be too much 'droop' in the system.
  • Online Sheriff \"Murph\"
    ryan what kind

    of shower valve do you have?? maybe a bad cartridge!! do you have the arresters (sheriff get it?) at the fixture as suggested?? the expansion should be at the cold inlet, and set at a few pounds under "working presure" of the system, checks and the looos bib screws seem to be good places to look!!
  • Harry Lewis
    Harry Lewis Member Posts: 2

    You can't install a bladder expansion tank in any system without checking the charge pressue in the bladder. Typically they come from the factory with a 12 psi charge. If you are installing this on a system with 65 psi and then with the fact of the hot water expanding, my guess is the xt is water logged. It must be charged to the pressure setting on the prv coming into the building. Also if you have installed water hammer arrest. the must be installed per the manufacturers recomd. You can not just cut it into a main line via a tee with the arrestor installed in the branch. The shock will bypass the location an transfer the hammer to th piping.....
    Good Luck
  • Bill_14
    Bill_14 Member Posts: 345
    Hey Ryan

    You got that problem solved and fixed yet? What did you do? Let us know so we can all feel better that we tried to help ya.

    Bill Russell
This discussion has been closed.