Difficulty adding new zones

Discussion in 'Irrigation / Sprinkler Forum' started by nagr22, Jun 28, 2006.

  1. nagr22

    nagr22 New Member

    Jun 28, 2006
    Whidbey Island
    I have recently added a second set of sprinklers, 4 zones (Rainbird rotating and sprayhead) for the front yard as an extension of the line for the backyard. I have a 6 zone similar setup for the backyard. The front yard rotating sprinklers will not function properly if anything, even a single hose is running anywhere on the line. That would seem to be inadequate pressure and/or volume.


    We are in a four-house division served from a 5000 gal. storage tank with a 1hp centrifugal pump set approx. 8 ft below the top water level in the tank. The pump is fitted with 1†intake from1 ½†line, with 1†outlet to1 ¼†line out, then to 2†main to the houses. Connections at the main are reduced to 1†line to connect the houses. At present, we are the only houses occupied.
    The irrigation system is teed from the 1†house line. From there it runs approx. 400 ft to the backyard system, dropping about 10’. When I added the front yard system, I extended the line another 200’ and back up the slope about 10’ in elevation. All main sprinkler lines are 1â€, then ¾†to individual sprinklers. In the backyard I can run 3 LG 3 (2.0 to2.3 GPM) impact sprinklers plus I have another set of two or three spearheads operating at one time, pump pressure from 30 to 40 psi. In the front yard, I can only run 2 LG3 sprinklers with basically nothing else on or the sprinklers will stop rotating. The 1 hp pump maxes out at 40 psi.
    Because we have a total of 10 zones plus other yard watering needs, plus the house needs, I would like to run at least two zones at a time using a total of approx. 12 GPM.

    1. Looking at a Flowtec chart, it indicates that a 1 hp at 40 psi delivers 17 gpm max. A 1. 1 ½ hp delivers 33gpm. I realize that is under optimum conditions etc.

    2. QUESTION: Will changing to a 1 ½ or 2 hp pump help solve the problem or is it basically the length of line that I am running?

    3. If not, would a booster pump on the downside of the backyard help to operate the frontward zones?

    4. If I install a booster pump, what safeguards are necessary? (Someone mentioned in the forum of sucking the water out of the house supply or of backing up when the system is off. The house is actually higher than the sprinkler systems.)

    Any help with this would be greatly appreciated.

  2. Bob NH

    Bob NH In the Trades

    Oct 20, 2005
    New Hampshire
    The developer put in a cheap water system to serve four households that you are trying to use as though it is all your own. When all of the houses are occupied, you are all going to have problems. Someone should start getting all over the developer before he escapes to some faraway island with all of the money. I saw a system like this where the neighbors at the highest house couldn't get any water at peak times of the day.

    You want to run 12 GPM. What do you think is going to happen when all four houses want to run 12 GPM on a 17 GPM pump? Someone should tell the developer that there will be no more occupancy permits until there is an adequate water supply. You and the others (yet unnamed) are headed for a disaster.

    If you put a booster pump on the line, you will be creating a hazard for everyone. You will suck water out of the line, possibly creating a vacuum in the suction line that will suck in dirty water from the ground. Every house on the line will get contaminated water, and when your pump is running, they will get no water.

    Someone should raise the issue with whatever public agency is responsible for development and water supply. It is headed down a road which leads to lawsuits and big expenditures to fix the problem. It will probably also lead to water use restrictions unless/until it gets fixed.
    Last edited: Jun 29, 2006
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