Grundfos UP-15 overhaul

[N4NV]

Technically it is the replacement of the cartridge in a Grundfos AU-15 pump:

Vince

[IntheGroove]

I have replaced so many of those I've lost count...

[jdurand]

Only thing I've replaced on ours was one had a leaking seal on the flange. They've been running since the 1980s, what makes them die?

[IntheGroove]

Continuous use in a hydronic heating system takes their toll on them...

[N4NV]

My problem was a check valve located too close to the pump that would allow an air bubble to form every time the pump stopped. As the bubble grew the pump would cavitate and just run dry until the bearing gave out. I moved the check valve and have not had a problem since.

[Slim-123]

This year, such an “operation” awaits me. Thanks to N4NV for a visual lesson.

[jdurand]

Guess we have friendly water or something. I do have pump lube in the water along with the other additives. There's also a fine Y strainer just ahead of the pump.

Maybe it's all those years working on industrial equipment, I just automatically added the strainer and additives when we built the system.