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RPZ question

Discussion in 'Irrigation' started by GrazerZ, Jun 17, 2005.

  1. GrazerZ

    GrazerZ LawnSite Senior Member
    Posts: 671

    Bid a job the other day were the customer requested that I use the sillcock as the point of connection. OK fine. used my handy dany tester and we have 15GPM @40 PSI. (Its a small two zone area with no real potential of expansion.)
    Before I agreed to install such a system I check to make sure that the building has backflow prevention. It has a 3/4" RPZ for all water needs in the building. But its about 100' away from the Point of connection mentioned.The pipe goes veritcal from the sill **** about 15' into the ceiling before traveling to the RPZ. Recently I spoke to the plumbing inspector for the area and confirmed that the building has to have a RPZ to be legal with an irrigation system. My question is, would you do such a thing? or would you insist on a $400.00 RPZ install just for the irrigation system?
    When I handed him my quote he asked about it. I told him that he would be legal and that I designed it as he requested. He mentioned that some other contractors want to put in the RPZ for $400.00- I assume its an easy upsell on such a small system if they did'nt know any better.
    Your thoughts Please????
  2. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Posts: 2,781

    Seperate backflow for the sprinkler system. If code requires an RPZ, the that's what they get. Can you put in a PVB? You have to protect the domestic water within the building from backflow.
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,646

    Where in the plumbing is this RPZ? Right after the meter? Feeding all the building? Or is there a single line feeding nothing other than the hose bibb(s) with the RPZ feeding only that line?

    If it's the latter, I'd say you're good to go. If the former, then the sprinkler system still represents a cross-connection with the building, and a backflow preventer is needed.

    By the way, one can use a half inch size RPZ on a hose bibb connection, and get a little over 10 gpm through it, which is as much as you might usually expect from that sort of connection.
  4. GrazerZ

    GrazerZ LawnSite Senior Member
    Posts: 671

    I called the plumbing inspector for this town at the end of the winter and from what he said, this situation in this town is legal. However, I am going to call again on monday to double check, I find that they often "change their minds". I did tell the guy that I recommend putting in another RPZ, but that I designed it as requested.
    By the way, do any of you ever do small systems off existing hode bibbs? I see them around here pretty frequently for small one and two zone stuff.
  5. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,646

    Any building that has people in it, would assumably have a potable water supply in it as well. Hook a sprinkler system to said building, without backflow protection, and you have a cross-connection that no building code would permit. Don't forget that government employees enjoy some immunity from the results of giving out bad advice, so they can say anything, and not suffer as a result. The humble sprinkler guy is another story.

    If you're on flat ground, you could use vacuum breaker backflow protection. The cheapest way to feed a 2 or 3 zone sprinkler system with backflow protection is to use anti-syphon valves. Let gravity cover your tail. Much more reliable than government officials. (and acceptable under BOCA codes)

    A hose bibb(s) connection is common enough, if the costs are in favor of it. The water pressure can either be so high that you get a good flow through the hose bibb, or it can be so low that you don't gain much more flow by plumbing more directly. If you have enough water to cover the area in a reasonable time, then what the hey, go for it.

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