I saw the old pump and the new pump, both 2hp. And the flow of the new pump is very good. It’s a 3 phase Franklin submersible and it’s putting out 9-10 gpm at the house. The well is 680’ total and the pump is at the bottom of 33 20’ pipe sticks.
Maybe the Oakville table I referenced is not typical. It was just the first I found.
Maybe the check valves are the answer?
Check valves are probably a necessary evil at your depth, but they definitely don't help to compensate for pump capacity. You get a small pressure drop across each check valve, equivalent to the spring pressure divided by bore cross-section, probably just 0.5 PSI. Their function is to avoid system bleed-down, with larger vertical drops (higher pressure at pump).
A 5 gpm, 1 hp pump stops pumping at about 660', so a 2 hp should do just fine depending on the series.
Yep. But he has a 10 gpm pump. Remember, HP is just an ability to do work, that work being the product of both pressure and flow. For a given size motor, you can only achieve higher flow by transitioning to an impeller design that will cost you in pressure.
Some water wells can be very deep at over 800’ or more while others are shallow at 50’ or even less. Water demands vary from just a few gallons per minute to hundreds of gallons per minute. In this overview we are going to explore the factors affecting the selection of the correct submersible well
oakvillepump.com
Not sure but I thought I read somewhere that installing more than one check valve wasn't a good idea. Wish I could remember but it was something to do with one locking up the next one due to pressure being trapped against a closed valve...or something LOL.
I ran into this problem in my last house. What happens is that all check valves have a small leak-down rate. But if one farther down has a higher leak-down rate than one up higher in the system, the result is it pulls a relative vacuum on the line. The pressure switch up top doesn't see this, since it's isolated from the line by a check valve up top. But when the pump kicks on, it's slamming fresh water up into this vacuum, and "bang!"
The system where I observed this had only one check valve up top, just upstream of the pressure switch, as the whole system was only 150 - 200 feet deep. It made a hell of a racket, every time the pump kicked on. I had a well specialist come take a look at it, as my knowledge is just general plumbing (we didn't have wells where I grew up), and it took him about 8 seconds to look at the system and tell me to remove that check valve up top... not necessary. After that, everything behaved well, but I wouldn't know what to do with a 600 ft. deep well.