Grundfos MQ3-45 water boost pump problem

[MJ]

This Grundfos pump is a tankless pump...no external pressure tank...that is designed to turn on and off per a flow switch. For the past week or so, the pump has been acting strangely when water is turned on. This "on demand" pump goes on when a faucet is turned on but it very consistently shuts off abruptly and turns immediately back on every 12 seconds or so...4-5 times per minute, every minute, every time. No matter how many faucets are on.

Has anyone seen this symptom and know if it is repairable or does the pump need to be replaced?

[John Keiser]

I think you can disable the auto-restart feature on your pump. Might try that and see what happens.

[wallis]

wallis had written this in response to

: I just read your question 5/12/2008 and I have exactly the same problem, did the answer you got of turning off auto reset work or what did? Thanks

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[wallis]

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[aidan]

there is a common fault with these pumps,the mother board gets faulty,(surging)looking into finding a replacement board hopefully

[JAMES BOHANNON]

My Grundfos MQ3-45 ran perfectly for 3 years to the month then all of a sudden it just stopped running. Kept my water psi at 60. Was that too much pressure for the pump I wonder why is just stopped. Thanks