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Mainline Size and Material Transition

Discussion in 'Irrigation' started by Gator Fett, Jun 21, 2006.

  1. Gator Fett

    Gator Fett LawnSite Member
    Messages: 10

    I've searched the forum and found a lot of usefull information. Thank you. :drinkup:

    I plan on installing an irrigation system in the next few weeks. I still have to gather my pressure and flow information as well as lay out my system, but I have a few questions first. I have a 3/4" copper supply in my basement with a 5/8" meter. From what I have read my plan was 3/4" tee with 3/4" isolation valve in basement. Increase from 3/4" to 1" copper in basement. 1" copper out through block wall to 1" PVB. 1" copper out of PVB into ground and into valve box. 1" copper female adaptor to 1" PVC male adaptor in valve box. 1" PVC manifold to Rainbird DVF-100 control valves. 1" PVC out to each zone.

    Am I on the right track? Is there anywhere else you would you recommend I make the transition from 3/4" to 1"? And then from copper to PVC?

    Thanks in advance.
  2. WalkGood

    WalkGood LawnSite Bronze Member
    Messages: 1,910

    Copper is expensive, save some money. Run 3/4" copper all the way out to the valve box. Use a 3/4" sweat x 1" pipe thread adapter to the manifold and/or master valve (if you use one). Make sure you have a blow-out plug if the PVB does not have one.
  3. PurpHaze

    PurpHaze LawnSite Fanatic
    Messages: 5,496

    You're on the right track. Good luck with your system. :clapping:
  4. Gator Fett

    Gator Fett LawnSite Member
    Messages: 10

    Thanks for the reply. I was worried about pressure drop in the mainline supply piping, thats why I planned on increasing to 1" inside the house. I will have a better idea of my pressure drop, once I layout my system and do all the calculations. I guess I will have to make my decision then.

    I am planning for a manifold drain in the valve box, and blow-out plug on the outlet side of the PVB and a mainline drain in the basement. Thanks for the reminder. :)

  5. Gator Fett

    Gator Fett LawnSite Member
    Messages: 10

    Thanks. :dancing:
  6. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    As PurpHaze said, you're on the right track. No need to downsize to 3/4", the price of copper from 3/4" to 1" is moot.
  7. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    This has always been my attitude, whether the pressure was high enough to allow the use of 3/4 anyway. I have a pet peeve with the guys who insist on saving 5 bucks on a 3/4 DC or PVB instead of installing a 1" device. WHY? does shaving 5 bucks really make a difference you need? If it does, I don't want the work. I have seen to many systems installed in new neighborhoods that had excessive pressure new and then 10 years later, the pressure is low and nothing works right. I know some will argue that saving that 5 bucks means someone makes more money later, but I can't seem to work that way. I want them to still be my customer 10 years from now, and I don't want anyone to suggest it was my fault.
  8. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,267

    I don't always upsize to one inch. It depends on the length of the run, and the available flow. I do like to use backflow preventers that use the same parts, whether it's one inch or 3/4 - makes service easier.
  9. Gator Fett

    Gator Fett LawnSite Member
    Messages: 10

    Thanks for the additional comments guys.

    I've taken my pressure and flow readings and calcualted my total pressure loss, and will make my transition from 3/4" to 1" just after my isolation valve in the basement.

    Where do you recommend I make the transition from copper to PVC?
  10. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Underground, before your manifold.

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