Question about Grundfos MQ3-35 3/4 HP Pressure Booster Pump
I have the same problem and have found that the inlet check valve has a broken shaft in the center of device. It is a multi-piece plastic unit and it looks as if it is not quite seating and therefore the internal pressure leaks slowly back into my low pressure suction line. The pump will start and the pressure will build then shut off for about 30 minutes then cycle again. I am going to replace the check valve.
Posted on Apr 18, 2010
Check the pressure switch/flow switch.
Posted on Mar 06, 2010
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Posted on Jan 02, 2017
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