Yes the J10S would be a much better pump. It will build a max of 67 PSI while lifting from 20'. This means with a CSV you want to run the pressure switch at about 37/57 max. I like to stay 10 PSI below the max pressure the pump can build for safety reasons.
The larger the pressure tank, the closer you set the CSV to the pressure switch off setting. With a 37/57 pressure switch and a 20 gallon tank (5 gallon draw) you would set the CSV for 55 PSI constant. This way the tank fill quickly to 55 PSI. The CSV will then hold 55 PSI constant for as long as you are using water. Then when all the faucets are closed, the CSV only has to fill the tank from 55 to 57 at 1 GPM, which should only take about a minute.
The pump will run longer because of the CSV, which is good for the pump. But the amps will be reduced by the CSV, so the little longer run times do not add up to much energy use.
The larger the pressure tank, the closer you set the CSV to the pressure switch off setting. With a 37/57 pressure switch and a 20 gallon tank (5 gallon draw) you would set the CSV for 55 PSI constant. This way the tank fill quickly to 55 PSI. The CSV will then hold 55 PSI constant for as long as you are using water. Then when all the faucets are closed, the CSV only has to fill the tank from 55 to 57 at 1 GPM, which should only take about a minute.
The pump will run longer because of the CSV, which is good for the pump. But the amps will be reduced by the CSV, so the little longer run times do not add up to much energy use.