Pressure switches and pumps

when you have a 20/40 or 30/50 etc. switch how do you know which one to use. Why do you use different ones.

Mark

You can use either switch. Your well tank precharge needs to be 2-3 # lower than the turn on pressure. You find out with a pressure gauge like you test tires with and you check your tanks charge with no water pressure in the line. You can add air or remove air as needed to fit what ever pressure switch you want to use.

those two switches are identical with different factory settings. each switch can be adjusted up or down. it is simpler to start out with a given cut in/cut out then to adjust each switch.

Most water systems I work on have 30/50 switches installed. It's really a matter of preference, as to how much pressure you want or need. Most city water pressure in this area is around 45 psi, so we try to keep the rural houses at about that same point.
If you have a 2 story house you'll probably want a little higher pressure for that 2nd floor shower.
And, of course, you have to consider the capabilities of the pump and well in sizing the pressure switch.
Ron