Pretty sure I've got this, but would like confirmation.

One zone of 4 on my boiler is not putting out heat. Gas company came out, gave boiler, valves etc. the thumbs up and say they believe the line has air in it and is not flowing. They can't do anything because they are not plumbers. So it's going to be -14 this week, and I have no heat in 1/4 of the house.

I did this many years ago, but would like to confirm what I remember from looking at my system.

  1. Zone feeds, just beyond the zone control valves, with positive stops and drains on each: ![zone feeds](https://imgur.com/QHltdfq)

2.Common return to boiler, with drain valve. ![common return](https://imgur.com/tbyBGyJ)

If I: a. Shut down boiler. b. Shut positive stops to all zones (orange handles in pic 1). c. Attach drain line to offending zone drain (in pic 1) into bucket of the glycol mix. d. Attach pump to drain line in 2 and feed from glycol bucket. e. open both valves and start pump

I should push glycol up through the return line, through the offending zone and back out it's drain, pushing out air and refilling line.

Correct? Or will I have a problem with the pump in 2 being in the return line I am trying to push the glycol through?

I don't want to screw up my boiler with even colder weather coming, let me know if I am overthinking this or missing anything.

THANKS for any help!

  • imgur.com/QHltdfq – Ward Moberg Dec 27 '17 at 21:28
  • imgur.com/tbyBGyJ – Ward Moberg Dec 27 '17 at 21:29
  • 1
    First - is this a glycol system at all? Many are plain water. Second, have you looked (carefully, they are not always convenient to find and often hidden under baseboard covers or in closets, etc.) for air bleeders on the affected loop? Third - what does the pressure gauge on the boiler say? It's a bit hard to make out in the second picture. – Ecnerwal Dec 27 '17 at 22:49
  • Yes, it's glycol. No, there are no bleeders on that loop, I've been over it multiple times, and grew up with such systems. I only have a single bleeder valve in the house. Pressure and temp are normal for the boiler, I look at those pretty regularly, around 170 and 15 psi. – Ward Moberg Dec 28 '17 at 2:08

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