Read your manual for installation, operation, and safety information. This guide neither supplements nor replaces the Owner’s Manual.
Adjusting Well Pump Pressure Switches
The stopping and starting of jet and submersible water pumps is controlled by a pressure switch. The pressure switch is typically preset correctly for the application. If the cut-off or cut-on pressure needs to be changed, follow the procedure described here.
Cost (0-5 scale): 0
Difficulty (0-5 scale): 2
• 3/8 and 5/16 nut drivers
Step 1 – Remove the cover
CAUTION – Hazardous voltage. Disconnect power before working on the motor or the pressure switch.
It is important for safety reasons to disconnect the power to the pressure switch. Then loosen the acorn nut that fastens the switch cover to the switch. Carefully lift off the cover.
Step 2 – Adjust pressure
For a one-post switch:
A one-post pressure switch provides one adjustment for both cut-on and cut-off pressure settings. They typically provide a 20 PSI pressure differential between the start (cut-on) and stop (cut-off) pressures. A single post switch looks like this:
To increase both cut-on and cut-off pressures, turn the nut clockwise. The rate of increase is 2-1/2 PSI for each complete rotation of the nut. In example, two complete clockwise turns equals a 5 psi raise in pressure setting.
Clockwise arrow art = cwarrow2.eps
Counterclockwise arrow art = ccwarrow2.eps
For a two-post switch:
A two-post pressure switch provides adjustment for both cut-on and cut-off pressure at the same time on one post. The second post permits adjustment of the cut-off pressure independently. A double post switch looks like this:
To increase both cut-on and cut-off pressures without changing the pressure differential (nominally 20 PSI), turn nut #1 clockwise. The rate of increase is 2-1/2 PSI for each complete rotation of the nut. For example, two complete counterclockwise turns equals a 5 psi lowering of the pressure setting.
Very few applications will need adjustment of nut #2. Nut #2 adjusts the cut-off pressure at the same rate of 2-1/2 PSI per complete rotation.
NOTICE - Never adjust cut-on pressure below 20 PSI or cut-off pressure above 60 PSI.
The cut-on and cut-off pressures in a well pump system must maintain a set relationship. Cut-off pressure is the high pressure that turns off the pump. Cut-on pressure is the low pressure that starts the pump and is typically 20 PSI less than cut-off pressure.