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Thread: Do sprinkler systems kill PRV's?

  1. #1
    DIY Senior Member Runs with bison's Avatar
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    Default Do sprinkler systems kill PRV's?

    I'm wondering if the short life of the PRV's in my home plumbing is related to the sprinkler system. Unlike the previous homeowner that apparently thought he was growing corn, I only use the sprinklers during extended dry periods/drought...all of this summer unfortunately and now extending through fall. When each station first comes on the line has to be inventoried and the high flow rate results in a noisy valve chatter from the PRV as it is running out the end of its performance/flow curve--sounds like a gasoline motor firing up for several seconds.

    Thoughts?

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    DIY Senior Member BobL43's Avatar
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    Quote Originally Posted by Runs with bison View Post
    I'm wondering if the short life of the PRV's in my home plumbing is related to the sprinkler system. Unlike the previous homeowner that apparently thought he was growing corn, I only use the sprinklers during extended dry periods/drought...all of this summer unfortunately and now extending through fall. When each station first comes on the line has to be inventoried and the high flow rate results in a noisy valve chatter from the PRV as it is running out the end of its performance/flow curve--sounds like a gasoline motor firing up for several seconds.

    Thoughts?
    So you have replaced several of those valves already? I assume from what you said that each of the the lines have automatic drain valves on them? I used to have them on my system, but sometimes they failed to close when the zone pressurized. Now, I just blow out all the lines in the system at the end of the season. My zones come on several times a week, so they really always have water in the lines, except maybe the one that is at a lower elevation.
    I am definitely not a pro plumber, but I am a pro crastinator

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    In the Trades Gary Swart's Avatar
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    My irrigation system takes off from the main line before the PRV. Why would you reduce pressure on your lawn sprinklers anyway? My system is arranged like this. From the meter at the street, the line comes in about 3 feet and is 5 feet underground. At that point, the line tees. One leg continues to the house where the PRV is located. The other leg goes into a stop and waste valve and then come up to the back flow preventer. This is in a control box that is flush with the lawn level. After the BFP, it goes across the yard to the side of the house when the zone valves and manifold is located, also in a control box that is flush with the ground. The sprinkler control is located in the basement opposite the zone valves. Inside the house, I have two lines for outside use that take off of the house line prior to the PRV so the hoses will have full pressure. These lines are protected with anti frost and anti siphon hose bibs.

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    DIY Senior Member Runs with bison's Avatar
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    My system wasn't designed by me (keep that in mind.) Street pressure can be pretty high here, in the range of 120 psi at night, hence the PRV. Our lawn sprinkler draw is after the PRV as are the hose anti-frost hose bibs.

    I've replaced the PRV twice already...once 4 years ago, once this year, although this year's replacement was due to a crack in the union probably due to shoddy work by the plumber on the previous job. However, I had already noticed some greater offset in DP under load in a PRV that was only 3 years old at the time. I've got sharkbites in it now so that it will be an easy DYI and therefore isn't so f****** expensive to replace in the future. The valves in the yard are self draining, although I also blow the lines out each fall using compressed air on a regulator, cycling through the stations twice per Rainbird's instructions. (Seems to work better than my neighbor's reliance on self draining heads...he's replaced several busted heads each year.) The flat sections still blow a lot of water this way before they blow air. Even with careful draining, I've had to replace check valves to the sprinkler master valve in a previous year, and the master valve body this year when it fractured at the gasket face...this of course ending up being a major hand excavation project since I didn't install any of this and didn't know what pipe I had to work with.

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    Plumber jimbo's Avatar
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    Should be no relation....unless your sprinkler systems are flowing too much water for pipe size/prv rating. What is the gpm flow of your zones? What size pipe and what size prv?

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    In the Trades Gary Swart's Avatar
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    At the risk of getting off of the original question, I'd like to add a note about self draining gizmos. When I installed my system, I put these things in as I thought it would save the expense of blowing the lines in the fall. HA. I soon realized that I couldn't be sure they were working so I blew the lines anyway. Then about 3 years ago, I noticed a large hump in my yard! You guessed it, one of the drainers was stuck open. With 3 zone lines in the same trench and over 2 feet deep, it was a real bear to get to the thing, but I finally was able to get in unscrewed and replaced with a plug. I now have a fairly large (60 gal) air compressor and blow my own lines each year. Takes longer that the yard service guys with the industrial compressors, but it's not a difficult job. I'm keeping my fingers crossed that I don't have anymore drainers stick open.

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    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by jimbo View Post
    Should be no relation....unless your sprinkler systems are flowing too much water for pipe size/prv rating. What is the gpm flow of your zones? What size pipe and what size prv?
    No problem there. It is the inventorying of the lines that sends the PRV way over rated flow for awhile, resulting in chatter. Valve chatter is something I generally don't like to experience. In the cracking plants I recall certain towers had a tendency to relieve during upsets and could chatter so hard as to loosen their flange bolts...not good on an ethane tower.

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    DIY Junior Member Mitchgo's Avatar
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    Sounds likes a bit of water hammering is going on.

    Does the noise happen when the sprinkler system turns on or turns off ( Very important) Are you sure the noise is coming directly from the prv? Where is the PRV located in relation to the point of connection for the irrigation system and does PRV serve just the house ? Sprinklers? Or Both

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    DIY Senior Member BobL43's Avatar
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    Runs says the problem happens when it is first turns on and the water line are being inventoried (filling up from being empty) He also said in another post that the PRV valve feeds the sprinkler system too, because of very high line pressure.
    I am definitely not a pro plumber, but I am a pro crastinator

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    DIY Senior Member Runs with bison's Avatar
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    Quote Originally Posted by BobL43 View Post
    Runs says the problem happens when it is first turns on and the water line are being inventoried (filling up from being empty) He also said in another post that the PRV valve feeds the sprinkler system too, because of very high line pressure.
    Correct.

    The sound is definitely coming from the PRV as I discovered standing next to it when a station turned on and subsides as the sprinkler heads all begin flowing. It happens each time a station is cycled on. It does not happen on shut off.

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