How can a New Jet Pump Cause Pressure Switch Problems?

[mnocket]

I'll TRY to keep this short... I had a new pressure tank installed because the bladder broke. Everything worked fine. Several weeks later I decided to replace the jet pump because the service tech said my pump was 25 years old. That's when the problems started. They installed a new jet pump and pressure switch. I lost water 3 times in next week and each time although the points in the switch appeared closed, I found that the pump would start if I pushed on the points.

I called the installer and they came and replaced the pressure switch.
Same problem persisted.
They once again replaced the pressure switch.
Same problem persisted
They replaced the pressure switch.
Same problem persists

It's pretty clear that the problem isn't the pressure switch. By process of elimination it must be the new jet pump causing the problem. I can't understand how a pump can cause the pressure switch to fail to close. I do notice that when the pressure switch comes on, the points don't close smoothly. They kind of do a "double bump".

Any idea how a pump can interfere with the operation of the pressure switch. The installer is understandably reluctant to replace the jet pump since when it gets power it works fine. It seems to be some sort of start up issue.

 

[fixitron]

Is is not quite clear what you are trying to describe. You stated: "I lost water 3 times in next week and each time although the points in the switch appeared closed, I found that the pump would start if I pushed on the points."
Were the switch contacts indeed closed? If they are open, there is about 1/8" gap that is visible between them. When you push them closed, does the pump start? Does the water pressure then increase until the pump shuts off?
What do you mean by "I lost water"? When you "lost water" did you physically close the contacts and the pump started pumping?
Does the pressure switch have a lever on the base, outside the cover? (That would be a low pressure cutoff switch.)

 

[Valveman]

A double bump on pump start is because there is too much distance and too many small elbows between the pressure switch sensing line and the pressure tank. If you plug the sensing line in where the pressure gauge is installed it will take out the double bump. Or you can install an additional pressure tank directly on top of that tee on then pump where the top plug is. Either way will get the sensing line closer to a tank.

Now when there is no pressure in the lines the pressure switch points should be closed. You should not have to push the points closed. But when a switch double bumps on pump start, sometimes it trips the overload in the motor. This overload will cool down in a minute or two and the pump will just come back on. I am wondering if it is a coincidence that when you close the points it is just that the overload has had time to cool and that is really what turns the pump back on?

That is a Square D switch. And while they can give problems I doubt you would see 3 bad ones in a row. You can't filter the suction side of a pump as that would create too much restriction for the pump to work properly. See NPSH for an explanation.

I would just install a new switch where the pressure gauge is attached and not use the switch on the pump.

 

[RenewDave]

I would check and see if the pump is losing it’s prime. Just a thought.