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Water Hammer Arrestors

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  • #31
    Re: Water Hammer Arrestors

    I'm surprised they don't require one for irrigation solenoid valves. They make a big band in my house.
    When I have an occasional hammer problem, I usually try to fix the problem, but if I can't find it, I have resorted to treating the symptom with a hammer arrestor. As for San Francisco, when using air chambers, I believe they require an access panel and a bleeder valve for recharging.

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    • #32
      Re: Water Hammer Arrestors

      Originally posted by drtyhands View Post
      Showers? How do you access them?

      What about flushometers?
      YES!
      On commercial batteries where multiple flushometers would be installed, we do.
      Our code specificies they are to be installed on any fast acting valve.
      We usually install them residentially on laundries & shower valves.
      Our code requires they be 3/4" and be at least 16"-18" long.

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      • #33
        Re: Water Hammer Arrestors

        Originally posted by Killertoiletspider View Post
        We've been installing them in high rises for 90 years, with no problems, and some of these buildings have over 100 PSI water pressure on the lower floors.
        That's what I say.

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        • #34
          Re: Water Hammer Arrestors

          Oh, Adam...I don't install the mini-trol in enclosed spaces.
          They come in handy on toilets under the basement ceiling or under vanities or KS's.

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          • #35
            Re: Water Hammer Arrestors

            Originally posted by Plumbus View Post
            As for San Francisco, when using air chambers, I believe they require an access panel and a bleeder valve for recharging.

            Last time I worked there, no access panel required, and no bleed down valve per say required. Just a 12"(on 1/2") or an 18" (3/4") air chamber just before the connection to the fixture. So on a shower valve, lets say, there would be no real drain down once it fills up.

            Greg

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            • #36
              Re: Water Hammer Arrestors

              Originally posted by glkearns View Post
              Last time I worked there, no access panel required, and no bleed down valve per say required. Just a 12"(on 1/2") or an 18" (3/4") air chamber just before the connection to the fixture. So on a shower valve, lets say, there would be no real drain down once it fills up.

              Greg
              Shutting the riser off and opening all the fixtures would drain them down just fine, gravity always wins.

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              • #37
                Re: Water Hammer Arrestors

                Originally posted by Killertoiletspider View Post
                Shutting the riser off and opening all the fixtures would drain them down just fine, gravity always wins.
                Ground floor shower, piped from above, water trapped at valve level no where to go. Most of the time the drain down does work. I had a astronomy professor who's token phrase was. "Gravity is Boss."

                Greg

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                • #38
                  Re: Water Hammer Arrestors

                  Originally posted by glkearns View Post
                  Ground floor shower, piped from above, water trapped at valve level no where to go. Most of the time the drain down does work. I had a astronomy professor who's token phrase was. "Gravity is Boss."

                  Greg
                  Think outside the box, pull the the valve stems.


                  My philosophy professor always told me gravity sucks.

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                  • #39
                    Re: Water Hammer Arrestors

                    Originally posted by Plumbus View Post
                    I'm surprised they don't require one for irrigation solenoid valves. They make a big band in my house.
                    When I have an occasional hammer problem, I usually try to fix the problem, but if I can't find it, I have resorted to treating the symptom with a hammer arrestor. As for San Francisco, when using air chambers, I believe they require an access panel and a bleeder valve for recharging.
                    Don't you have an r.p. on your irrigation system?
                    "Man will do many things to get himself loved, he will do all things to get himself envied." Mark Twain

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                    • #40
                      Re: Water Hammer Arrestors

                      "An expansion tank will often eliminate this in my experience also. If it's on a well the bladder tank can absorb some too. "

                      Both these components are upstream of the point where the water hammer occurs so will do little to arrest the problem.

                      "A physical body will remain at rest, or continue to move at a constant velocity along a straight path, unless an external net force acts upon it." Newton 1687.

                      The water will want to move in that straight path unless acted upon by some external force, which in the case of plumbing is a fitting which changes the direction of water flow. A long run which dead-ends into a T or 90 or a quick-acting valve ends up absorbing all that force. The placement of anchor points and shock arrestors can not be done haphazardly and expect the problem to be eliminated, it could be made worse.

                      If your code requires shock arrestors (WHAs) then you should be including them in your bid, not begging to have their costs covered later on. If you feel that this added material cost may cause you to lose the job then point out that you have included the cost of WHAs and their installation in your bid as required by code. For other bids to be compared to yours equitably, they should also include (or be adjusted to include) the WHAs or maybe technically they should be rejected as non-responsive bids since they don't conform to to code requirements.

                      You are responsible for supplying all the materials to install the system to code right? If the A/E misses a code required item who is gonna get called on it...YOU the plumber will. Why, because of the catch all cover their a** clause that the A/E always puts in the specs stating the contractor is responsible for ensuring the installation is to code. Your license also states that you must install per code.

                      Down the road you could be held liable for damages or injuries caused by improperly installed piping. This happened in a hotel where the hot water line was not properly supported and WHAs were not placed per the drawings. Years later the HW line blew apart (failed joint at a 90), hot water rained down on hotel guests and scalded a number of them.

                      Analyze the placement of your WHAs and position them so they absorb the majority of the force. This may mean adding a tee and installing the WHA on the end of the run and the supply to the fixture being fed off the branch of the tee.
                      "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
                      John Ruskin (1819 - 1900)

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                      • #41
                        Re: Water Hammer Arrestors

                        Originally posted by glkearns View Post
                        Ground floor shower, piped from above, water trapped at valve level no where to go. Most of the time the drain down does work. I had a astronomy professor who's token phrase was. "Gravity is Boss."

                        Greg
                        How often is this draindown maintenance needed on a residential application? I think I understand Spiders reasoning and proof in commercial. But for residential:

                        How many times are you called to do a draindown for a customer? You know they don't know what to do about it.
                        If very little, then aren't they becoming waterlogged, no banging pipes, and probably unnecessary?
                        If very often, then isn't it overmaintenance that could be eliminated with piston type mechanical ones?

                        Don't want a debate. Just the best way to do things based on everyones experience. I have some customers that have had the piston type in for 5+ years with no callbacks for banging pipes or to maintain/replace them OR for any draindown.

                        Thanks.

                        J.C.

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                        • #42
                          Re: Water Hammer Arrestors

                          Originally posted by JCsPlumbing View Post
                          Piston type mechanical arrestors. I have no idea why site built air chambers would be required or allowed.

                          J.C.
                          Because before mechanical arrestors existed this is how the problem was dealt with. One would think they would have been removed from new construction now that mechanical arrestors have been available for over 25 years.
                          "When we build let us think we build forever. Let it not be for present delight nor for present use alone. Let it be such work that our descendants will thank us for, and let us think, as we lay stone upon stone, that a time is to come when these stones will be held sacred because our hands have touched them, and that men will say, as they look upon the labor and wrought substance of them, "See! This our fathers did for us."
                          John Ruskin (1819 - 1900)

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                          • #43
                            Re: Water Hammer Arrestors

                            Originally posted by Bob D. View Post
                            Because before mechanical arrestors existed this is how the problem was dealt with. One would think they would have been removed from new construction now that mechanical arrestors have been available for over 25 years.
                            That's what I meant. I don't know why they would be required or allowed today.

                            Spider makes a good case on the commercial side. But I do think with proper engineering the draindown maintenance could be eliminated.

                            J.C.

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                            • #44
                              Re: Water Hammer Arrestors

                              I like what I've heard so far.Especially about the lawmakers listening to lobbying insurance companies.

                              We have a code.I try to follow it best I can because it makes things easier in the long run.I don't like spending time trying to figure out what's necessary.

                              Some guys have said they put them on everything(damn near) in order to provide a complete product.I've overseen the completed thousands of water systems containing tens of thousands terminations,some quick closing,most not(obviously).The plumbing is secured properly.There are no problems,period.Although I haven't been doing this for 90 years I think 25 ought to be a good enough track record.

                              Adam

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                              • #45
                                Re: Water Hammer Arrestors

                                The only time I have run into water hammer is when the pipe size is too small and the velocity increases. The Illinois code causes water hammer by allowing undersized pipe. I never run 1/2" in a house except to sillcocks, and the last fixture.

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