SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

The first thing you should do is draw up a design plan and determine how much GPM and PSI you will need. Select a pump that fits those needs that you calculated. I am assuming you are going to have a submersible pump, correct?

I would go with the 40 PSI, maybe even a 30 GPM pump. I would also recommend that you consult a local well digging company to see what pump would suit your local needs.

Thanks

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I am able to get head to head coverage on 5 zones with 7 rotors per zone. There fore my question is how many gallons per min, if I want 2.5 gpm per head? Am I correct in saying I need a pump that will deliver 20 gpm so that I can still take a shower etc while my system is running? Also if I tell my well guy that I want 20 gpm should it also be at 40 psi or 20 or 30? My longest run of pipe is about 130 ft.
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The whole idea is so that your pump turns on ONCE, runs constantly through the entire time all of your zones are watering, and then shuts off when it's done. Otherwise (i.e., if your pump "catches up" with the cutoff every so often because the zones don't have enough gpm draw on them), then your pump will be constantly turning on and turning off during the watering cycles. You'll end up replacing that pump much, much sooner.

7 rotors @ 2.5 gpm = 17.5 gpm per zone, and this does not take into consideration ANY pressure or rate loss for your backflow preventor, mainline, valves, elevation, lateral pipe runs, etc. (you can't just figure your rate on ONLY the head rates).

You also didn't state what flow rate the well was rated at (perhaps you don't know yet).

My suggestions would be a 20 gpm pump (based on your well specs, mine is a 3/4 hp rated @ 20 gpm). If your well specs are like mine, you'll be pulling about 15 or 16 gpm by the time you hit the heads (based on your runs and selection of parts). Honestly, I would suggest 6 zones @ 6 heads per zone (assuming all 2.5 gpm rotors). You might get away with the 5/7, but I don't know that I'd do that.

I would also suggest a 1 1/4" mainline and then 1" from your valves to your heads. You lose about a quarter of the PSI (per 100ft) with the 1.1/4" poly versus the 1" poly.

Also, don't "build" a manifold. Put your valves in your mainline (separately) where each zone feeds off. That way, you use less 1" poly to the zone (versus a manifold of 5 valves in one single spot in your yard) and the pressure loss is negated.

Ditto drpete.