Diehard is doing pretty good. The CSV is just a simple valve. It works like a pressure reducing valve as long as you are using more than 1 GPM. The spring in the CSV pushes the valve open when there is less than the normal 50 PSI setting. When less flow is needed and the pressure increases above 50 PSI, the water pressure actually closes the CSV to make the pump produce less water. There is no electric to the CSV, it is pressure operated. When no water is being used the CSV closes down to 1 GPM. There is a bypass in the CSV that can never close to less than 1 GPM, which is still several times more flow than needed to keep the pump/motor cool. When no water is being used, the CSV closes to 1 GPM, the 1 GPM has no place to go except the pressure tank, which is filled to 60 PSI and the standard 40/60 pressure switch shuts the pump off.
As long as more than 1 GPM is being used the pump never shuts off. When no water is being used the CSV fills the pressure tank at 1 GPM rate, which allows for a much smaller tank than if it were filling at the max pump flow rate. The part that is hard to understand is that when the flow from a pump is restricted with a valve, the amps drop the same way as if the motor was being slowed down with one of those computerized, expensive, and problematic variable speed pump controllers or VFD.
The CSV takes advantage of the natural drop in amps when a full speed pump is restricted with a valve, while a VFD is slowing the RPM and tying to trick a pump into doing something it already does naturally.