Help! My Hydronic heating system keeps destroying circulator pumps.

Jamie Hall

I'd almost bet on cavitation, given the location and look of the damage. Inadequate pressure at the inlet of the pump...

DZoro

Thinking that nice strong, powerful new pump, started to kick but with the rust and sludge.
For the last 50 years they had old pump, slowing flows, low pressure. Everything was fine. Now have new shiny strong pump, big water pressure, higher water flow, higher water velocities= sludge chunks everywhere.
Like was mentioned @JohnNY at the first post, strainer/separator, maybe new pressure tank, air scrubber, full system flushing, may take a few good flushes over a couple weeks.

Jamie Hall

If the inlet pressure is too low on that pump when it's running, it's going to cavitate. And the bigger the pump the worse it's going to be. I'd reconfigure the whole show to ensure that the pump inlet is at the pressure tank. The rest of the stuff is nice to have -- but cavitation will kill you.

LeoB

Have posted twice, but the comments seem to have vanished. If this is a repeat, please ignore.
I have tried several Armstrong 37479 pumps on my S-25 system, and while they run fine without load, under load from the pump they heat up and start squeaking loudly. Tried a Rotom motor, and it also squeaked under load after heating up, but not as much. I set up a large fan to cool the motor, and the squeaking stopped. It would be interesting to know whether the sleeve bearing design, including metallurgy, of newer motors is the same as older ones. The issue could also be the lubrication of the sleeve bearing.

KC_Jones

@LeoB

They moved you to a new thread for your problem. Stuff tends to get lost when you piggyback on someone elses problem, and it can make it difficult for other users to differentiate between your system and that of the OP.

Go here to see your new thread with comments.
https://forum.heatinghelp.com/discussion/194781/system-keeps-ruining-circulator-pumps#latest

Erin Holohan Haskell

Thanks @KC_Jones.