Pump with pressure tank question.

Discussion in 'Irrigation' started by jcom, Jun 18, 2008.

  1. jcom

    jcom LawnSite Senior Member
    Posts: 791

    We are set to start an installation where the customer has had a well drilled. There is a pressure tank sitting next to the pump casing and they have left a 1" pump outlet for us.

    Of course we will do a flow and psi test before design. The pump is wired to a pressure switch by the tank. The pumps we have put in before have not used a pressure switch to avoid excessive cycling of the pump. My thinking is that the tank will alleviated this problem and the pressure switch is ok.

    We plan to come off the outlet to a manifold and mainline and turn the pump on. When a valve opens the pump will start etc. etc..

    Is my thinking all messed up or workable.

    I know you gurus are here!

  2. Dripit good

    Dripit good LawnSite Bronze Member
    Posts: 1,081

    How old is the tank.......and is it exposed to the elements? If new you should be fine with what you plan to do. If old and not brought inside for the winter, the bladder could be shot rendering it useless.
  3. jcom

    jcom LawnSite Senior Member
    Posts: 791

    All is new.
  4. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Posts: 47,697

    Run a serious test on that well. an hour's pumping might not reveal a problem that two hours pumping would. (This is about low replenishment rates, as you pump out water) ~ When you determine the flows that give you constant operation, you can design a proper system.

    You should specify a controller that has a programmable delay between zones, on the off chance that you have a well that can run dry, which would have to sit idle, while it refills.
  5. Dripit good

    Dripit good LawnSite Bronze Member
    Posts: 1,081

    Don't forget about your back flow assembly before your manifold.
  6. Valveman

    Valveman LawnSite Member
    Posts: 53

    You don't want to make the pump start relay in the sprinkler controller override the pressure switch. Let the pressure switch start the pump when the zone valves open. Now all your zones have to exactly match the output of the pump to keep it from cycling. Or you can use a Cycle Stop Valve before the pressure tank. This will allow you to match the zones to the irrigation required, without having to match all zones to the maximum output of the pump. If the zones don't max out the pump, the home owners will still have good "constant pressure" even while the sprinklers are on. If the zones max out the pump, there is very little left for the house.
  7. Dripit good

    Dripit good LawnSite Bronze Member
    Posts: 1,081

    Yes, yes! We have two systems we service that run out of water within 45 minutes of run time, that takes approximately 2 hours to recover.
  8. AI Inc

    AI Inc LawnSite Fanatic
    Posts: 25,390

    Definatly listen to this guys advice. Run a hose into the woods and let it run wide open. Drain your staorage then you can get a real reading of what the well is producing.
  9. Valveman

    Valveman LawnSite Member
    Posts: 53

    You certainly need to know how much the well and the pump will produce. You should test the well at least as long as the irrigation will be running. It is possible that you can have a 20 GPM pump but, the well will only produce 15 GPM for an extended period of time. In this case you can't set the zones to 20 GPM or the well will go dry, and you can't set the zones to 15 GPM or the pump will cycle on and off. Using the CSV, you can set the zones to 15 GPM and the pump will not cycle.

    The same way a CSV will allow you to design the zones to match varied irrigation requirements, it will also let you vary the zones to match the amount of water available from the well. So if the well test out to make 17 GPM, you can use a 20 GPM pump, and still design each zone for only 17 GPM without the pump cycling.
  10. Puttinggreens

    Puttinggreens LawnSite Senior Member
    Male, from southeast PA
    Posts: 376

    Please explain how the cycle stop valve works.

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