Pressure tank replacement for Grundfos CU301 and SQE07-240

[Djsav]

Hi- During a recent water softener and RO servicing, I was told that my pressure tank is waterlogged. I pressed the tank pressure valve and water came out. The current pressure tank is a WellMate WM14-WB. The CU301 documentation calls for a 2 gallon pressure tank. Is there a reason why a larger tank might be needed or can I just replace it with a 2 gallon tank? Also, the water pressure release valve (100 psi) has opened up more than once. I replaced it, but it happened again. Would a waterlogged tank cause a spike in pressure? Thanks

 

[Valveman]

With the narrow pressure bandwidth the CU301 works with, a large tank is not helpful. You will only get a tiny amount of water out of a faucet before the pump starts, no matter what size tank you have. Yes, the prv popping off could be from the waterlogged tank. But it is more likely caused by the CU301 losing contact with the motor. This happens so often with the CU301 that it is programmed to act like a pressure switch, cycling the pump on and off quickly, and doesn't even show the fault light for "loss or connection" until it has done that about 1000 times. Losing connection with the motor because it uses the power wires as communication cables as well power to the motor is one of the CU301 biggest problems.

I would replace the tank with at least a 4.4 gallon size tank because that is the smallest tank we recommend with a Cycle Stop Valve. That way you can replace the CU301 with a regular pressure switch and let a Cycle Stop Valve deliver the constant pressure as needed. Many CU301 controllers have been switched to Cycle Stop Valve control to have something that will last a long time without giving any problems. But something that last a long time and doesn't give any problems is called a disruptive product in the pump industry, which is why they push any other type of control including VFD with is what a CU301 is.

VFD Repair Kit – Cycle Stop Valves, Inc

Upgrade any variable frequency pump system to a reliable constant pressure system.

cyclestopvalves.com

 

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[Djsav]

Thanks, Valveman! Appreciate the information!