Shallow well pump with pressure tank: what would you check before choosing one?
We're off grid on 20 acres in west Michigan. Water comes from a shallow well, roughly 18 ft down to water, feeding a 1hp jet pump that's about 12 years old and a 20 gallon pressure tank.
Last week the pump started running nonstop while the gauge sat around 10 psi and the taps barely trickled. Reprimed it, got a day of normal pressure, then it dropped off again.
I'd rather not buy a new shallow well pump and find out it was something else, so before I do anything I pieced this list together from old threads here, the jet pump manual, and the guy at the farm store:
Water level. A shallow well jet pump only pulls from about 25 ft, and after a dry summer I want a real number.
Foot valve. A leaky one drains the line back and the pump loses prime.
Suction side leaks. Any crack or loose fitting lets air in, and the line from the well head is the original galvanized, so I'm not ruling that out.
Pressure tank. Precharge about 2 psi under cut-in, checked with the tank drained. Mine never has been.
Pressure switch. Tube under it clogs.
Inverter startup. Whatever goes in has to start on my 4kw inverter without tripping it.
If it does turn out to be the pump, I've been looking at the Aquastrong PGA150SAN. The appeal for me is it comes mounted on the tank with the switch and gauge already on it, so it's a straight swap rather than piecing it together. It also cuts out on dry run, which after this week sounds pretty good. One solar user mentioned it pulls a fair bit of power, so number 6 on my list still stands.
Anyone had a jet pump run with no pressure like this? What was it?