Got a secondary pressure source for my domestic water, which is run through a radon aerator unit. The pump is cycling on and off at an alarming clip. At times it was about 7 or 9 seconds between the pump being shut off then turned back on again. This is with a tap open
I bypassed the radon setup immediately and have shutdown the pump so I can figure this out.
What is causing the short-cycling? I adjusted the screws in the pressure sensor, so it kicks on at about 35PSI and off at 55 or so. Reading the gauge on the line exiting the pump, it will peak at 55, the pump shuts off, then the needle will drop very quickly to 30 (a tap is open), the pump will kick on, pressure goes back up to 55, and so on. The water in the tap surges visibly when this happens.
This is a Grundfos pump, 8 years old, I know it has cavitated a bit in the past as I had some issue with air getting into the pump (or the intake line) at some point intermittently. Was trying to figure that out when this cycling problem started.
Pressure tank that the pump is perched atop is a Well-Mate. Could that be bad?
Just trying to isolate the problem here…any help appreciated, thanks.
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Replies
Tank bad
If the tank has a bladder, it could have a hole in it, the water replacing the air volume, causing rapid cycling of pump.
Old tanks didn't have bladders, and eventually the air in the tank would get absorbed in the water, necessitating the need to shut of the pump, and dain the tank to establish the air volume.
I'm betting it's a bladder failure.
Good luck.
The first assumption is that you have a "waterlogged" pressure tank. With the newer bladder-style tanks this means either the bladder has a leak or the pressure setting in the tank (the Schrader valve on top) is wrong -- too high or too low relative to the pressure switch settings.
The other possibility is a bad check/foot valve.
In addition to your waterlogged issue, your pressure sensor may be full of crud, ru;st and such.
Probably the pressure tank.
The switch is doing what it is supposed to do: On at 35, and off at 55. So, it is probably good.
The pressure tank could easily be the culprit.
If it is one of the of the non-bladder tanks, turn of the pump, and drain the tank, so that it is full of air. This should fix the problem.
If it is a bladder tank, set the prepressure to 33-psi, (2-psi below your pumpt start pressure), with the tank drained, and see what happens. This is done by turning off the pump, and with a valve open, setting the air pressure in the tank.
If it is still short cycling, the tank is probably bad. Drain the tank, disconnect it and jostle it a bit, and listen for sloshing water. If there is any the bladder has a leak, and the tank will have to be replaced.
Thanks for the replies, everyone. Sorry it took me so long to get back. Will try to diagnose further with your suggestions and will report back.
recycling water pump
Do you have a check valve on this system? There should be one on the outlet side of the pump before the pressure tank. Indeed the bladder on the tank may be bad but it's my experience that check valves have a shorter life expectancy.