PVC in the North

Discussion in 'Irrigation' started by cenlo, Mar 22, 2005.

  1. cenlo

    cenlo LawnSite Senior Member
    from Ontario
    Posts: 322

    I keep reading about using poly in the Northern climates and pvc in the Southern. I don't understand why? If all the water can be blown out of the lines prior to the first frost then whats the problem? Please advise? I am going to be using a mini trencher (I no, it's not as good as a plow) and laying 3/4" - 1" pvc mains. Most applications are 4-6 zone properties. I thought with the 3/4" mains, they would still offer some flex.

    Thanks in advance, Cenlo
     
  2. Broker

    Broker LawnSite Senior Member
    Posts: 382

    The Poly is better for the annual freeze and thaw. I fix broken PVC lines every year to to freeze damage. We don't install PVC on Residentials in northern Ohio but if you are stuck on it because it is easier to use in an open trench then it gives you that much more job security as some people might say. I know that it is cheaper overall to install then poly too.
     
  3. cenlo

    cenlo LawnSite Senior Member
    from Ontario
    Posts: 322

    Are they damaged by ground shifts of by poor blow-outs?
     
  4. Broker

    Broker LawnSite Senior Member
    Posts: 382

    They are damaged because PVC becomes brittle at a faster rate then poly, as the system gets older the integrity of the pipe is weakened. I could say the the blowouts might not have been done correct but in the same breath I could say if the winterization is not done correct for a PVC & Poly system you are more likely to have freeze damage on a PVC system. Most of the repairs we make on other systems with PVC are lateral too not just main. Every system should always have a PVC main, because you should never have poly under constant pressure. Remember that all of this stuff that I am telling you is just what I have learned through the years from experience, suppliers and the IA. So I could be wrong & take it for what it is worth. It seems like what ever type of system someone was trained on have it be PVC or Poly it is what they will stick with. Email the IA if you want a technical answer with data to back it up.
     
  5. cenlo

    cenlo LawnSite Senior Member
    from Ontario
    Posts: 322

    I was planning on (for most jobs) 1" pvc to the valves and then 3/4" pvc for the zone mains. From there I would use 1/2" "funny pipe" to the heads. Would that make a difference?
     
  6. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,990

    Stick with poly pipe in colder climates, and you will have happier customers. PVC gets brittle with cold and age. and the shifting of the soil from frost and heave can fracture PVC. And unlike a small split in a poly line, when and if it should ever develop a leak, a PVC pipe can split for an entire 20 foot length. Digging up 20-odd feet of your customer's lawn will not make you their favorite person.
     
  7. JeffY

    JeffY LawnSite Senior Member
    Posts: 324

    I use PVC to valves and poly afterwards. I too have come across busted PVC during sprinkler turn-ons due to freeze damage/brittle PVC. If you're going to use PVC throughout the whole system, I would use 1" to your valves like you said, and then 1" to your zone mains. You can then step down to 3/4 after that. The whole purpose is to maximize your flow and pressure efficiently. If you step down to 3/4 right after the valves, you will lose suffer greater pressure loss at the furthest head. With the funny pipe, you should limit it to 6' and 1 head.
     
  8. cenlo

    cenlo LawnSite Senior Member
    from Ontario
    Posts: 322

    Is there any other piping in 20' lenghts that would be better? Or how can I straighten the poly to keep it in the trench? Thanks, Cenlo
     
  9. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,990

    You buy poly pipe in big rolls, like 300 feet (or maybe 100 meters) for one inch poly, and use a vibratory plow to pull it without trenching. If you see a good how-to page on poly pipe in a trench, the straightness is not only unimportant, you will see advice to have the pipe snake from side to side in a trench. This is because the pipe can shrink a bit when it gets colder in the winter. (despite that shrinkage, it doesn't often affect systems with poly pipe pulled in straight lines by a plow)
     
  10. cenlo

    cenlo LawnSite Senior Member
    from Ontario
    Posts: 322

    I understand poly pipe comes in rolls. I can't pull it with a vibe plow because I will be using a mini trencher. The poly rolls are about 48" - 60" dia. I imagine that when it is 50 deg. outside in the morning it is not going to lay in the trench very well!
     

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