bad pressure switch??

I am no well/pump expert but have changed a pressure switch a couple times on this unit since 1995. Lost water and replaced pressure switch Monday evening and this am when I got up and no water. An hour after I switched the power off, switched it on an the pump started running. Even though it is a 20-40 switch, the pump is running and the guage reads ~52 when it goes off. I tried adjusting the small nut to make it shut down sooner but that has no effect. When I turned the large nut counter cw the pump shut off. Later when water was used, it seemed pump would come on every time when normally this would not be required. At at some point, the pump would not go off and I shut power again. I checked the valve on top, drained tank and pressure is now~t 34. I am beginning to wonder if I bought a defective pressure switch. I have always gone to the same Bowen supply but this time although the switch looks the same it is not the SquareD brand I am familiar with, still have box from previous as I had drawn picture for hooking wires back up on it.

The small adj is normally the differential and the large one sets the pressure.

You may have a loose connection to the switch, or dirty contacts.

Could also have a restriction / debris on the pressure input to the switch, Your gauge could be reading off some also.

SquareD brand is good.

The smaller of the two springs can be used to increase the cut-out and/or delta but cannot decrease the cut-out below what the big spring is set at. The big spring will raise/lower both the cut-in and cut-out at the same time, keeping the delta about the same.

When you lower the cut-in, you must lower the precharge on the bladder as well. Keep in mind that neither your water pressure gauge nor your air pressure gauge are to be trusted. Either can be off. When setting the air precharge, your air pressure gauge needs to be calibrated to the water pressure gauge. When not at zero, the water pressure gauge reading should be compared to the air pressure. Both should read identically. If they do not, at least one of them is lying.

The best way to set tank precharge is to drain all the water out and then check & set the air charge to 2 psi below cut in pressure. I don't trust el cheapo tire pressure gauges so I use a a tire inflation chuck with a glycerin filled gauge to check the tank pressure. Throw the cheap dry gauge out and install a stainless steel glycerin filled gauge.

Sounds more like the nipple the pressure switch is attached to is clogged up than a bad switch.

JBax said:

I checked the valve on top, drained tank and pressure is now~t 34.

Click to expand...

This statement is not clear to me. What did you actually do by checking the valve on top and why before draining the tank? Is it the air pressure on the bladder after draining that is 34 PSI or what? A 20/40 switch should have 18 PSI precharge but after screwing with both adjustments, it's impossible to know now.

Before you fiddled with the nuts, I would concur with valveman that you have a blockage in the nipple but now it might be more than that.

The old switch must have been adjusted for around 35/55.