Circulator not moving water

MikeG

Yesterday I just reconnected two BB pumped zones.  They were disconnected for a couple of years for remodeling and a boiler relocate.  The zones are pumped with Grundfos circs.  Since they were off for a few years and some new BB added, I flushed the system. There is a dirt separator, and I installed Y strainers on both zones.  It all worked yesterday, but this morning one zone is not moving water.  The pump is running (very hot), no air in the zone.  Is the usual culprit a stuck internal pump check valve or solder balls in the pump.  The pump is new.  I can pull it off and clean or switch out easily but looking for any other thing I missed or ideas.  Thanks  Mike

Jean-David Beyer

I am not a pro.

Could those Y-strainers be clogged already (depends on how much dirt is in there)?



I do not know if there are check valves in Grundfos circulators, or how to tell other than taking them out and looking. With Taco ones, there is a sticker that says IFC on the ones with check valves, and the part number says something like that too (on the little metal plate). The Taco ones do not look like they would get stuck shut: the water pressure acts to open them, and the spring holding them closed is pretty weak. I suppose they might get stuck not fully open, or might not close completely if something got stuck in there. Of course, anything is possible. I have Taco 007-IFC circulators in three places, and one non-IFC one. But since I have had them only a little over a year, I have had no problems.

MikeG

Good flow past strainers

The strainers are not plugged yet.  When I flushed the system it wasn't bad, but who knows what can break loose.  It filled and purged without a problem.  It worked fine yesterday, even heat throughout the BB with minimal noise.  Thee pumps have internal flow checks.  More likey to stick open then get plugged.  I will have to pull the pump and check it.  I have an extra so just as easy to replace if I have to.  I hope I find something, so I can at least feel I fond a difinitive cause.  Thanks  Mike

meplumber

Sounds like air to me

What is your system pressure?  12 PSI won't always do it.



But I would bet that you still have air trapped.  Try a power purge with a transfer pump.



Good Luck.

MikeG

I think that was it

System pressure is 12 PSI.  I isolated the zone and purged it again.  Didn't see any air bubbles but it is now working OK.  I have vented ells with coin vents on all the BB at high points.  Hopefully the air eliminator will take care of any other air. That trapped air will get you every time.   Thanks Mike