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pwinters

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Wednesday, October 4th 2017, 5:13pm

Switch to Bigger Pump?

Hi, hoping someone can help. I currently use a Goulds GT10 to pump out of a pond to irrigate approx 2 acres. Most zones are Maxi paws, 5 heads using the largest nozzle. I believe it generally is doing about 35 psi and pumping 35 to 38 gpm. Something in that range. I had a professional from a local irrigation store draw it up and tell me what to install. This was 10+ years ago. At that point I had 5 zones so I could easily run through the zones frequently. I now have nearly 15 zones and looking to add a few more. My problem now is I'm running sprinklers all the time and walking all over turning them on and off. To get to my question, is it possible to change out the pump for a GT20, to increase gpm and possibly run 2 zones at a time instead of 1?

Specifics, the pump sits about 40 ft from the pond and only a few feet higher than the pond. Foot valve sits in pond around 3 ft deep. Intake is 2 inch pipe, my main line is 1 1/4. Zones are 1 inch. All use sch 40. GT10 runs on the 230v setup. Help would be greatly appreciated. I imagine electricity usage would increase but I believe I could run the pump less to offset some.

Thanks!

Wet_Boots

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Posts: 5,147

Location: Metro NYC

2

Friday, October 6th 2017, 3:07pm

You have a problem in that a 1-1/4 inch main line is not large enough to carry increased water flow. For a 30+gpm flow to not suffer pressure loss, the main line should be 2-inch. If you are going to even consider running multiple zones, you will have to replace the mainline. Should you make the replacement, you could find that your existing pump can drive two zones at once.

Since a larger pump does not give you a great increase in pressure, you have to find that extra pressure by way of eliminating the greatest source of pressure loss in the existing system.

If your zone valves are 1-inch size, you are definitely not running 35+ gpm in your zones.

Since Maxipaws have interchangeable nozzles, they might be reworked to use less water, and make it possible to run two zones at a time (maybe even three zones at a time) - the benefit here is that getting a flow rate into the 10-15 gpm range reduces pressure loss in a zone valve.

pwinters

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Tuesday, October 17th 2017, 11:30am

Thank you! Makes sense. Digging up the mainline sounds like a nightmare. I guess it is what it is and I'll make due. Appreciate your time.

Wet_Boots

Supreme Member

Posts: 5,147

Location: Metro NYC

4

Wednesday, October 18th 2017, 1:42pm

If it comes down to needing more watering in a limited time frame, increasing the mainline size will easily be the most bang for the buck. Running two zones simultaneously with a new mainline will get flows-per-zone down below 20 gpm, and reduce pressure loss through the zone valves.

It's a lot of work, but you will get some of your investment back by more watering in a shorter time saving you electricity.

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