Jake, didn't answer some of your questions.
The rotation was checked several times, volts, amps. I've been
challenged by different people.
I'm just service not an engineer, however if something changed in the
system to change the load on this pump, it will show up when I
reinstall the old original pump, because I'm chicken shit to wait any
I "think" I know this much, when you shut off a discharge valve on a
centrifugal pump, and the motor amps are below full load, and then
barely crack it open and the amps go crazy, it's hard to believe that
it's the system. I've had a similiar problem before and it was a
solved by a larger horsepower motor for the system. It could have been
sized wrong, and operating on the end of it's curve. With this job, it
has a 12 or more year history of the same pump, with the balancing
valve open much further. The old pump's motor didn't fail, just the
bearings, and it needed a seal plate.
This pump is on a primary loop in a boiler room, with two boilers and
their pumps pumping thru the loop, and the secondary pumps are also
pumping thru this loop. I've had the other pumps off/on and the
results are the same. The primary loop probably isn;'t 50 feet around
the boiler room. So I think it's the pump/motor.
Crazy thing about this job, is they have two boiler, with their pumps,
and two secondary pumps, only run one at a time. However they only put
one primary pump on the system, if it's down your done. Go figure.
Like I said we'll see.