New plumbing created water hammer noise in 3 irrigation zones

Discussion in 'Irrigation / Sprinkler Forum' started by digitalshooter, Apr 10, 2014.

  1. digitalshooter

    digitalshooter New Member

    Apr 10, 2014
    In short, we remodeled a small master bath by gutting and removing old galvanized pipes and replaced with new copper. The new shower Kohler valve required 3/4 inch hot and cold main supplies. So new 1 inch copper supplies to this bath for hot and cold were upgraded from 3/4 galvanized to 1 inch copper then reduced respectively for 1/2 supply for toilet, 3/4 supplies shower and 1/2 inch supply for sink hot and cold. Water arrestors were installed on the hot and cold feeds to the new shower valve within 8 inches of valve.

    No other pipe noise while using anything in the house, but now there is a noise the last 3 irrigation zones turn on and switch between them, do we get what is described as water hammer in the house.

    Note that the 3 zones that are doing this, are located in the backyard and are closest to the remodeled bath.

    So to recap, the only plumbing changes that were made were: new 1 inch hot and cold supply tied into the exisiting old galvanized plumbing for the remodeled bath along with new copper for shower, toilet and sink. All other old galvanized to be replaced after this bath is complete.

    Used lots of tie downs for the new copper. Any thoughts or help would be appreciated.


  2. WorthFlorida

    WorthFlorida The wife is still training me.

    Oct 28, 2009
    Orlando, Florida
    A few questions: 1) Are you on city water or well? 2) Does the hammer sound occur when the irrigation zones are running or when they shut off? 3) During the hammer noise have you opened a faucet? If yes did the noise stop? Is the noise continuous or does it slowly go away. It reads like the problem is only when the zones change. If it is the water flow is turned off very sudden the water flowing has no where to go and bang.

    The noise you hear may not be cause by water hammer. If your on city water the pipe leading to the irrigation valves must have a anti back flow and vacuum break. A great site I just found, Google search anti back flow and vacuum breaker for pictures. How many zones total? The three that seem to be causing the problem how many sprinkler heads per zone. They might be the largest number or the smallest number of sprinkler heads.

    If you can cause the hammer to occur every time, run a faucet in the home. A true hammer problem the pressure is cycling and the water will come out of the faucet pulsing and it will slowly dissipate to a steady stream. Is it possible to turn off the water supply to the new copper only? If yes then see if the noise occurs. If you can turn off the hot and cold supply to the shower/bath faucets then do so and then test it again.

    Put a pressure gauge on a spigot and read the pressures for each irrigation zone and the pressure when the zone changes. Just more info to get a read on the system
    At any time if the noise goes away, at least you know the area causing it and you can look further into it.

    The bottom line might be that the problem was always there and since galvanized pipe is very very ridged and thick walled it was able to absorb the change in pressure and not rattle as soft copper can.
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