Please, a little help

Discussion in 'Irrigation' started by alf51175, Mar 22, 2007.

  1. alf51175

    alf51175 LawnSite Member
    Posts: 35

    I've got a system that has 5 zones. When the 2nd, 4th, and 5th zones come on there is hammer in the pipes in the house. The system is roughly 10 years old. I am leaning towards it being valve problems. If someone has experienced this problem and you could help, I would really appreciate it.

    Thanks
     
  2. high pressure with high flow and the valve shutting down is causing your water hammer...
     
  3. alf51175

    alf51175 LawnSite Member
    Posts: 35

    This happens as the zones are turned on, just as the zones pressure up. Happens for about 5 seconds.
     
  4. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    The problem is relatively new? The noise you are hearing is vibrations in the pipe because the flow of water in the pipe has reached a velocity that causes vibration. The most probable cause for this is that the valves are closing slower now with age. Irrigation valves close by using upstream pressure. Your controller stops asking zone 1 to be open and tells zone 2 to be open. Zone 1 is slow to close and zone 2 is taking pressure away which makes zone 1 even slower to close. Zone 1 can't close until the pressure in the mainline equalizes. Some controllers allow you to program a delay that allows the zone to close before then next zone opens. Other controllers offer a fixed delay that can be enabled. Repairing all of your valves might not fix the problem if a reduction in pressure has contributed to the problem. (ten years ago, pressure was at 90psi, now it is at 70psi). The decrease in operating pressure reduces a valves rate of closing. A delay between stations or insulating the pipes would be your best alternatives.
     
  5. alf51175

    alf51175 LawnSite Member
    Posts: 35

    Thanks, really appreciate it. Glad you guys are here.
     
  6. Flow Control

    Flow Control LawnSite Bronze Member
    Posts: 1,267

  7. aric43085

    aric43085 LawnSite Member
    from Ohio
    Posts: 71

    What kind of valves are they?
     
  8. alf51175

    alf51175 LawnSite Member
    Posts: 35

    They are Nelson's, don't know the model. After sleeping on it and thinking about it, I needed to add that this happens when those zones are turned on and start to pressure up if they are turned on first. Meaning, if I decide to turn on number 4 first it hammers. Which makes me believe that the valves are slow to open. What you guys think?
     
  9. aric43085

    aric43085 LawnSite Member
    from Ohio
    Posts: 71

    I think it is definitly the valves. I believe those old nelson valves are the same as the rainbird EV. When those valves get older, the diaphram will chatter causing water hamer. The best result I have had, is to replace the bad valves. If it is too much work, I would replace half now and half later. Hope this helps you out.
     
  10. alf51175

    alf51175 LawnSite Member
    Posts: 35

    No, all three valves are in the open and easily accessible. I think that is worth a try. Thanks.
     

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