To size a pump need gpm flow per zone and what zones do you want to double up. Next highest water level & suction of pump level to top of well. All pipe sizes, length of pipe and number of fittings each pipe. Take a pump apart will also need a shaft seal and possibly a brass sleeve. A pump shop or a motor shop might be a better way to go. Before I'd put money into that pump i talk with gould or a pump shop. Your pump isn't made for having the pump above the water level.
Thanks for all the help. It looks like these irrigation systems are more complicated than I want them to be.
IN SHORT: How can I choose a replacement for a failed (Goulds HSC20) irrigation pump? My system has had two HSC20 pumps over the past 18 years. The first one lasted over 12 years and then failed. The second one was installed 7 years ago and lasted 6 (through last summer) and then developed the problems I've been describing in this thread. So, with new HSC20's retailing for close to $2,000, I'm hoping to be able to start using a different make/model of pump for my system.
I bought this house with an existing sprinkler irrigation system, so I do not have all of its layout and design details.
Are these my two choices?
A. Easy method. Failed pump had adequate nozzle coverage, and pump did not cycle on/off, so I can replace the failed Goulds pump with the exact same model.
B. Impossible method. With huge effort, I can find all the necessary information of the multi-acre irrigation system to then determine the pump requirements, and then shop around: Pipe material, diameter, and length (layout is buried underground, so pipe routes are hidden) throughout the entire system; Flow rate, operating pressure, and friction loss for all 70 nozzles. And also document how the nozzles are clustered into control zones; Friction loss for every valve (check, main, qty 18 PGV) in the system; Elevation change between lake (my water source), pump, and every nozzle. I can simplify this method by making assumptions here and there (pipe material, pipe layout/length/diameter, specific nozzle configuration, etc.) but this could lead to selecting either an undersized or oversized pump — both of these situations are bad.
Method B might let me find a pump cheaper than the HSC20, if I am willing to do the work. (Sounds impossible to learn all the specifics of pipe routing, changes in diameters, t-fittings, etc without doing a lot of digging.)
What would a professional irrigation contractor do if a homeowner in my situation asked him to recommend and install a new pump?
Thank you.