I am glad you quoted the crap that Franklin is telling people. I maybe able to use that, but I wish you had gotten it in writing from them.
Franklin has a big axe to grind with the CSV. The CSV is disruptive to their industry. It makes pumps last longer, use smaller tanks, and does away with the need for their most profitable items like VFD’s.
Ever once in a while there is a pump system that defies the laws of physics. A pump lasting 35 years is the first unusual thing. Being set a few inches into the mud usually burns up a motor in a matter of days. But if you never use a sprinkler or anything that runs for more than a couple of minutes at a time, I guess the heat has time to transfer into the mud instead of water.
Because of the abundant rainfall and subsequent lack of irrigation in your area, pumps usually last a long time as they are very lightly used. I can see why you are confused about the heat buildup and transfer from a submersible motor. You are right that none of that happens when the pump is off, which yours is most of the time, so I see why you think that.
I also see why people would think a submersible would stay cooler in a large body of water as compared to “narrow casing”, but just the opposite is true. The motor is a foot or two below the intake of the pump. So without a current in the lake or well, the water around the motor can boil, while a few inches above the motor, cool water is going in the intake and getting pumped to the surface.
With a flow inducer sleeve or small diameter casing fed from below, a flow of water goes past the motor before entering the pump, which is what keeps the motor cool. Franklin motor cooling charts do not list a large body of cold water as acceptable. It states the required flow past the motor in feet per second. If there is no flow going past the motor, the heat from the motor can boil the water and destroy the motor quickly.
Most 2 wire submersible motors have a Biac switch, not a centrifugal start switch as in above ground type motors. It is not just the switch that is destroyed from cycling, but many other things as well. Shafts can be broken, splined couplings and impeller hubs can be stripped out, on top of burned pressure switches, start relays and capacitors. However, it is the “canned stator” design of a submersible motor that takes the most abuse from cycling. “Canned stator” means the windings are encased in solid epoxy. When the motor heats up the “canned stator” swells up. When the motor cools down the stator contracts. When the pump is cycling on/off rapidly, the stator doesn’t have time to cool down and contract before the motor is restarted. The stator is swelled up enough that the rotor shaves off a little meat when it starts turning. The shaved off debris gums up the motor and gets into the thrust bearing, which begins a quick death march for the motor.
Also Kingbury type thrust bearings have a film of water hydroplaning between the plates when spinning at least 50% of full speed. This film of water makes this type of bearing completely frictionless. As long as the motor is spinning at least 50% of full speed, there is actually no wear at all on a Kingsbury type bearing. However, each time the pump starts, the bearing runs dry until the pump gets to 50% of full speed. This grinds off a little of the bearing at each start, and is greatly exacerbated if the motor starts before it has time to completely cool down. So the fewer starts, the longer a pump/motor will last.
When a CSV restricts the flow rate, it just makes the pump think it is in a deeper well. Restricting the flow or putting a pump in a deeper well will increase the K factor and cause more down thrust on the bearing. So if “addition down thrust shortens the life of a motor” then they should only be installed in shallow wells, and any restrictor like a Dole valve, (which are very common on pump systems) should be strictly forbidden. Of course this is ridiculous, as submersibles will work fine in very deep wells. And the restricted flow from a CSV is not “inadequate to cool the motor”. Franklin should feel very foolish saying this as hundreds of thousands of successful CSV systems over more than 20 years proves that to be incorrect.
Oh and people who have installed thousands of pump systems would not call the “solid state switches the most reliable know to mankind”, we call them a piece of junk.
I wish you would contact Franklin again and get them to send that to you in writing. I am sure they won’t do it, but that fact would also be telling. Pumps are confusing enough without them spreading false accusations. But keeping things confusing is kind of their goal. If everybody understood what it took to make pumps last a long time, Franklin would go out of business.
Many things about pumps/motors are counter-intuitive, so it common for someone of your education to be confused on some issues. I teach classes to many pump engineers. Most of them are also confused. The counter-intuitive part of pumps and motors means the stuff they learned in school doesn’t apply in the real world. Don’t let Franklin confuse you even further. They will say anything to try and keep your new motor from lasting another 35 years.
And if I am wrong after saying these things for so many years, why hasn’t Franklin sent lawyers after me, or at least put someone on this forum to argue with me? I know they hate what I say, but they can’t argue with the facts. I would love a chance to argue with them in court or at least on a public forum, but they are not likely to let that happen. Wonder why??