No adjustment left on pressure switch to decrease cut out.

[steve82]

I have a Square D 40/60 pressure switch. The current installation has been in place for over 6 years. I noticed that it was not cycling at the correct pressures. I adjusted the middle screw to place the range between 40-60. Problem is it is actually cutting out at 62-63. I am out of adjustment on the top end screw (the spring is loose) to bring it down to 60. Do I need a new pressure switch or is something else wrong?

 

[Reach4]

Most likely you need a new pressure switch. They are not expensive.

First, I would turn the differential nut (on the smaller spring) CCW until the spring is loose. See if that fixes it. Normal 20 psi differential is usually obtained with that spring almost loose, but overdoing it will not be bad at this point.

If that does not lower the cutout as needed, it is possible that the nipple connecting to the pressure switch is clogged, causing the switch to be late to get the pressure. You could test for that by turning off the power to the pump when the pressure is 55 psi. If the switch turns off after a minute, then it could be the clogged nipple was delaying the pressure switch sensing the pressure.

 

[Sponsor]

 

[LLigetfa]

If the differential is greater than 20, it could be sediment buildup under the diaphragm but that usually manifests as not being able to set the cut-in. I've not seen it affect the cut-out. As Reach4 mentioned, the differential nut might need tweaking or the switch might need replacing.

 

[Valveman]

The little adjustment is the difference between on and off. Loosen it off and don't mess with it. The large screw adjust both on and off pressures accordingly.