Hydronic zone will not purge

catskilt

I have a multi zone hydronic system, every zone is working just fine except 1. The problematic zone air handler is on the same floor as the boiler (basement) so there is no elevation issue (the zone on the 2nd floor works fine).
When I try to purge the zone, by isolating all the other zones, attaching hose to the purge value and giving it full pressure... nothing happens. I get not even a trickle out of the purge valve, I have tried going back and forth moving fluid both directiosn but no breakthroughs. This zone worked fine last year. At first I thought I had an air lock, but now I am starting to think I have a blockage somehow. I am considering trying to bypass the hot water coil just to see if the circuit can flow, but figured I'd ask to see if there was something smarter I should try first.
Thanks for any help!!!

STEVEusaPA

I wonder if oxygen egress has clogged it. I'd cut the plastic pipe and have a look. See if you can get air thru the coil and air thru each pipe back to purge.

EdTheHeaterMan

No water or air going thru the pipes/coil? there is a blockage.
1. Do those circulators have Internal Flow Check Valves?
2. Is that zone circulator installed backwards?
3. From what I can see, the inlet is on the top of the problem pump and the inlet on the other pumps are on the bottom.
4. Remove the pump and reverse the flow. Then you can remove the motor from the pump housing and rotate the motor so the wire connection box is in the easy access location.

Big Ed_4

Maybe a bad check valve in the taco circulator ? Break the top flange looking for pressure after isolating the return .

pedmec

Circulator is in backwards. Obviously it has a check in it.

HVACNUT

Are you positive that 2nd zone circulator corresponds with that 2nd return? Is it possible the zone 2 supply is zone 1,3,4, or 5 return?
Where is the feed valve located and what pressure are you trying to purge with? Have you gone up to 25 psi?
I don't see how it could be upside down. It's in the same position as the others.

pedmec

You need to look harder. Its pumping into the manifold as the rest are pump away from the manifold. Look at the volute

HVACNUT

pedmec said:

You need to look harder. Its pumping into the manifold as the rest are pump away from the manifold. Look at the volute

It's hard for me to make it out in the pic, and the OP says it was fine last year. 

neilc

I see what Pedmec sees,
but I'd sure like that same picture from the other angle

pedmec

It will work. You'll just pump between the other zones and not the boiler. until the flocheck falls apart and close of the flow

catskilt

Thank you, I'll check the circulator and post an update.

mattmia2

Is the pex kinked somewhere?

catskilt

I am relieved and very embarrassed to say @EdTheHeaterMan & @pedmec have great eyes and I have a very dumb brain. Circulator was backwards!

EdTheHeaterMan

catskilt said:

I am relieved and very embarrassed to say @EdTheHeaterMan & @pedmec have great eyes and I have a very dumb brain. Circulator was backwards!

Don't Feel Bad @catskilt. I had a customer with this same problem. Complained about weird moaning and groaning noises for at least 3 years before I noticed the upside-down pump. If there were other zones calling, then there was no problem because the water flowing past the boiler aquastat would be able to shut off the burners when the boiler water was over 180°. The moaning and groaning would happen when the backwards zone operated by itself. The cold water entered the boiler at the aquastat probe location (supply side) while the hot water leaving the boiler went out the bottom (return side). So the water near the burners could be getting close to boiling point at 15 PSI (around 250°) because the cold water returning at the top would be keeping the limit artificially cooler.

Once I found the mistake… The Ghosts and Goblins went away.