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Hi guys, the pest is back. Water hammer problem

Discussion in 'Irrigation' started by jingles, May 4, 2006.

  1. jingles

    jingles LawnSite Member
    Posts: 26

    I installed three rainbird valves to replace toro valves. The toros never did this. The rainbirds work fine. I have a bad problem with water hammers on all three. This occurs only when they close. I had a repairman install a new back flow unit. Its a febco, this one I believe.... http://onsmartpages.com/kelleyslawn.../productsservices/category.nhtml?catuid=10113
    Any suggestions on how to cure this. Thanks for your help and patience.
  2. bdb

    bdb LawnSite Member
    Posts: 74

    The water hammer is caused by two things the velocity in the pipes...exceeding the recommended 5 feet per second and the valve operation. I know that Hunter's has a delayed or slower closing diaphragm's which helps eliminate the problem. Most other valves are instant on/off. Toro's flow pro's close slow and after they have been "broken in" and don't close all the way and weep.
  3. DarkLotus

    DarkLotus LawnSite Member
    from Florida
    Posts: 82

    Hunter, Nelson and Toro valves I believe are slow closing. I would never install a valve from either company though. If I have the water hammer hit after each zone, I would throw on an inline water hammer reducer. It costs between 5-15 from the supplier and I still keep the quality from the valves.
  4. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

    RB Dvs do shut down hard. I have "fixed" this once by changing to DVF and cranking the flow 2-3 times, and they didn't shut down as hard. Not saying it will do that for you. Just saying.

    Also check your pressure. High pressure can give loud clunking at shut off. Check and see if your pipes are not secured in the basement - if they are set up this way. Maybe they rattle against a joist when they shut down.
  5. jingles

    jingles LawnSite Member
    Posts: 26

    Thanks for the reply guys. I am going to buy a water pressure gage today and test the pressure. My water company had told me before that my area is prone to high water pressure and had installed a pressure reducer on my main line, that is adjustable. Also, DANA, what is a DVF .....DarkLotous I will look into the water hammer device. Can I install this, or should a pro. I am hoping my water pressure is to high, and I can simply adjust the valve to correct this. What should house pressure be to be in normal operating range. Again thanks for your help and patience all.
  6. DanaMac

    DanaMac LawnSite Fanatic
    Posts: 13,156

  7. Ground Master

    Ground Master LawnSite Senior Member
    Posts: 505

    Jingles- Try using a rainbird pga or peb valve. They cost more but are slow closing. Try one for the last zone and see how that works for you.
  8. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    Before you replace the valves you just spend tons of time installing, buy one Rainbird DVF, and change the bonnet on your Rainbird DV to the DVF bonnet (the bodies are the same).

    Try throttle down the flow control and if it helps, change the rest.
  9. Rainmaker

    Rainmaker LawnSite Member
    Posts: 11

    according to Rain Bird when this happens after a winterization you should manually open the valves from the bleeder screw to releive any air trapped in the valve I have ran accross this problem a number of times and 9 out of 10 times it worked
  10. maintenanceguy

    maintenanceguy LawnSite Member
    from NJ
    Posts: 156

    Water hammer is caused by the heavy slug of water moving through in the pipes slamming against the valve. Water is heavy and incompressable. It's like throwing a concrete block against a tree.

    Any plumbing supply will have a "hammer arrestor". This is a small air chamber that gets plumbed into the line leaving the house. The air chamber will absorb the energy of the impact. The more water volume you have in the line, and the faster it's moving, the bigger chamber you will need. Most are about 6" in diameter but you can get them much larger.

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