bad taco circulator?

I have a hydronic heating system with 4 zones. It is only 2 years old. There are 4 Taco 007 IFC circulator pumps on it and they have all worked flawlessly until now. 3 zones are fine, but the 4th isn't heating. The pump is getting power and I can feel the motor running, but nothing is pumping through at all, as the pipes are cool further up. Is it possible the cartridge is bad, or maybe there is air in the system? should I pull the cartridge to check it? I was thinking maybe the IFC could be bad too, but don't now how to tell.

 

Suspect air first... are there bleeders on the rads/baseboards?

Is it still bitter cold where you are? Any possibility that zone is froze?

Suspect pump LAST...

 

No bleeder valves on the baseboards. I have heard some gurgling in the line this year. It is cold, but this is the second floor and the rest of the house is pretty warm. The house is 8 years old and has r19 in the walls and has been pretty tight. We have had colder winters and never a freeze, but nothing is frozen as far as I can tell.

One weird thing though. I have shut down the other zones (shut off the supply and return ball valves) and shut down the return ball valve on this cold zone. I opened up the bleeder at the return (just above the return valve that I shut off) and nothing came out, even when the pump was running. It makes me think there might be something wrong with the Internal Flow check...cause even if the impeller was broken, the 12 psi pressure should move water through and out the bleeder at the return. Or, it is frozen (which I still doubt). could air lock up the IFC on the pump and how can I relieve it?

 

Are those pumps installed such that they are pumping UP?

It is possible for the IFC pumps to get 'airbound' in such a configuration... if there is air in the system, and it collects in the pumps volute because the IFC won't let it pass, the pump will just 'sit and spin' with no water in it. Bad for pump... very bad...

If this were the case, the only option would be to force enough water pressure through that zone that it opens the IFC and moves the air through. It may/could happen again. Removing the IFC and installing a separate flow check far enough up the pipe that collected air doesn't stop the pump is one solution. The other would be repiping and mounting the pumps so that air can't collect behind the IFC.

 

Yes, they are pumping up. I took the pump in question apart tonight and the check valve was fine and the impeller is fine. I could blow through it easy. Then I put it back together and still couldn't force any water through the bleeder on the return. I verified I am doing this right by repeating this for another zone and it worked fine. So it looks like I have a blockage in my 2nd floor zone. I am guessing something is frozen. It has been very cold here for a while (upstate NY). Tonight is 10F. It looks like it won't get above freezing until Thursday. Any way to help thaw a pipe? It has to be behind a wall (of course), and I have no idea where the issue is. Is there anything else it could be? I've never had a frozen pipe here and it has been colder.

 

Worse than a frozen pipe is a BURST frozen pipe... I suspect you will find it when it thaws...

If you have any idea where the pipes are in the walls, you can position electric space heaters around and try to thaw it ...

bummer... sorry for you...