Electric Pressure Switch
Electric pressure switches control the cut-in, pump-on, and the cut-off, pump-off, operation of the water pump. The switch contains two-main components, pressure springs and electrical contacts. The dual pressure springs are adjusted by two different sized nuts. The larger nut and spring combination controls the cut-in and cut-off pressure. The smaller nut and spring combination control the gap between the cut-in and cut-off pressure. Generally a 1/2-inch end wrench will fit the larger nut, while a 7/16-inch end wrench will fit the smaller nut.
Always shut off the electrical power before removing the gray plastic cover of the water pressure switch. Exposed electrical parts are present as soon as you pull the cover from the mechanism.
Raise the cut-in and cut-off pressure by turning the large nut in a clockwise direction. Turn the nut one-full-revolution at a time. Re-apply power and test the pump by watching the pressure gauge after opening a nearby drain valve. It may take a couple of pump cycles to adjust the pressure accurately. A low-pressure system will have a cut-in pressure of 20 PSI and a cut-off of 40 PSI. A higher-pressure system will use a cut-in of 30 PSI with a cut-off of 50 PSI. Never exceed an internal water pressure of 80 PSI as damage will occur to plumbing joints and faucets.
You can expand the gap between the cut-in and cut-off by turning the small spring nut combination in a clockwise direction. Use caution if you want to decrease the gap between the two. Turning the smaller nut too far in a counterclockwise direction will completely decrease the cut-in and cut-off gap to where the pump will run constantly. This condition will cause excessive water pressure to the system and damage pipe joints along with faucet valves.
Adjusting the pressure switch needs to be done a little at a time. Turn the nut, then run the water system to check the results of the adjustment.
The electrical contacts of the pressure switch WILL get damaged over time, it does matter what you do; keep a spare switch on hand at all times. The action of the small metal discs opening and closing causes the electricity to arc between the two points. Being in a wet environment the contacts will begin to pit and then eventually fail.
You can replace the small dual contacts if you are comfortable fumbling around with small retainer washers and even smaller springs. Leaks may also form at the plumbing connection under the switch or internally with the spring mechanism. In most cases, it is easier and less expensive to replace the entire switch.
Shut off the electrical power to the pump. Pull the plastic cover from the switch mechanism. Remove the electrical wires from the screw terminals. Make a note as to which wires connect to which screw terminal. Pull the wires from the switch.
Fit the jaws, of a crescent wrench under the switch housing, around the plumbing nut. Turn the housing in a counterclockwise direction. Remove the old switch. Apply some plumbing putty or Teflon tape to the male threads of the 1/4-inch pipe. Screw the new switch in place. Tighten with the crescent wrench, be sure to grab the housing with the jaws of the wrench around the plumbing fitting.
Connect the electrical wires back into the proper screw terminal. The switch should be factory adjusted for a high-pressure setting as described above. Install the cover over the switch. Re-apply power and let the system build pressure. Go buy another pressure switch and stash it nearby for the next time you need to replace the switch in about five years.
