Unusual well pump problem?

Question

I have a well pump that feeds into a large 8,000 gallon water tank. From there, the water feeds through a booster pump, through a pressure switch, to the pressure tank, then onto the water filter, softener, and the house, in that order.

The recent problem is this: after the booster pump has raised the water pressure to the cutoff point (60 psi), the booster pump cuts off, and you hear a swooshing sound in the pipes from the water softener all the way back to the water tank, and the pressure starts to drop. When it drops to the cuton point (40 psi), the booster turns on again. But, this time, the pressure only gets to about 50 psi and never gets to the cutoff pressure of 60 psi. The booster stays running continuously, you hear the swooshing in the lines continue, and the pressure stays a 50 psi forever. The booster never can cutoff and it runs continuously.

I checked the pressure tank. It is ok. Right pressure (2 lbs below cutoff) and is lightweight (not holding water). I replaced the pressure switch with a new one and set it to the right range.

When I turn off the booster pump for a few seconds, after the swooshing sound starts, then turn it on again, the pressure builds up to the proper 60 psi, the pump cuts off, the swooshing starts again, and the pressure drops again. When this happens, and I shut off the valve to the house, on house side of the water softener and the pressure tank, the swooshing continues and the pressure continues to drop, until the booster turns on again. BUT, if, instead of shutting the house side valve off, I leave it on, and turn OFF the valve between the water tank and the booster pump, the swooshing stops, and the pressure holds steady. All is good.

It's almost as if, after the pressure has built up, and reached 60 psi, and the booster pump has cut off, that the pressure built up in the line is being pushed BACK INTO the WATER TANK!

Has anyone heard of this? Is the booster pump impeller causing cavitation? Will a check valve help?

The fact that it can get into an equilibrium, with the swooshing sound in the pipe, and keep the booster pump running continuously, while keeping the water pressure between the cutoff and cuton pressures is strange, too.

Has anyone run into this before?

Answer 1

Yes. The problem is the way the tank is introduced to the system. If the tank is downstream  of the pump, with the switch in the same line, then it will read the same pressure. If there is a "T" in the line, then you may not get the same reading at the "T". The pump position in the system is important. I know this is confusing, but call your pump man.

Answer 2

sounds to me that you have a leak in your system somewhere,i would test everything that holds air with soapy water and  check any of your safeties and thier operation.has you filter been dirtier then usual? can yu valve off from after well to the house in sections? i am a building maintenece engineerand swooshing indicates air  in system  and not reaching 60 psi  could be from sucking in too much air in pipes constantly and its bleeding off at filter or softer=bner housing or somewhere else. and vibration at pump is from air aswell.soapy water everything you can looking for a leak(with pump on) because with pump off air might be entering your system under negative pressure.... you can email me at [e-mail] i will try and help  you through this if you like  

Answer 3

My boyfriend says that it sounds like you may have air in the line somewhere.  Good luck...don't lose your whole weekend trying to de-swoosh it all.

Answer 4

sounds like a faulty check valve to me

Answer 5

db Harm is on to something here but I think the check valve is gone. It is between the booster pump and the pressure tank and looks like a cylinder about 5 inches in lengthg and about 2 inches in diameter. It is probably not sticking but the valve in it has a chunk out of it. The bad thing is the swooshing sound is making the jet pump run in reverse and this is not too good for it. You need to get on this asap to avoid any more expense. Valve is only about 15 for a brass one. Booster pump 10 times that. Sorry. Hope this helps.

Answer 6

I believe the problem lies in the water softener.

They do vent waste salt water.

Have it checked.

Answer 7

You either have a bad check valve. This allows only flow in one direction in your pipe. When it has broken it does not work and when pump shuts off the water flows back toward the tank - thus the sound and the drop in pressure kicks your pump back on again.

The check valve is in the line somewhere or it could be a variation of a check valve that is at the very end of your suction line in the tank - this is sometimes called a foot valve, but it does the same thing.

Get this replaced because it is putting a lot of stress on your pump.

Answer 8

It sounds to me like the check valve in the discharge line from your booster pump to your pressure tank has not closed back tightly shut from the "get-go" and your water is leaking back through the booster pump every time it shuts down -- until when you CLOSED OFF the block valve between the booster pump and the water tank.  If you can determine where the check valve is in the discharge from the booster pump give it a light "thump" with a mall hammer right after the booster pump shuts down at the proper set pressure, and see if the check valve might break loose and start operating correctly.