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More Help Needed With Bleeding My Boiler

Rongold Member Posts: 21
Well, I changed out my leaking immersion well on my Weil McLain wgo6 boiler, and as recommended by you guys, I drained everything and flushed out the boiler and all 3 zones. The 15 year old anti freeze was pretty clear--not discolored as I expected it to be. I also changed both air vents. While flushing the individual zones, I closed the zone valves and the stop valves (what is the proper name for them--picture enclosed) in the returns to trap the water in each zone, and then let the boiler drain. I then filled the boiler itself with Cryotek -100 anti freeze through the pipe on the boiler that the vent mounts to. I managed to get 16 gallons in there. The whole system holds about 31 gallons. My house is big---a 4000 square foot split level. There is about 450 feet total of 3/4" piping with about 220 feet of baseboard on that piping. I then installed my 2 new air vents and a new pressure relief valve--The old one was jammed--couldn't even lift the lever. After all that, I opened the water feed to the fill valve, and the system pressurized itself to about 10 PSI cold. So far, so good--NO LEAKS. I started the boiler and let it heat up and then one by one, I turned up each thermostat. The playroom zone heated up OK. I turned that thermostat back down and then turned up the living room thermostat--That zone heated up OK too. I turned that one down and then turned up the bedroom thermostat--No luck with that one--The circulator pump was pumping & pumping, but no water circulation--That zone must be airbound. Now, I know how to bleed the system---I've done it before it had anti freeze in it, but this system has about $250 worth of anti freeze in it. Is there a way to bleed this without losing all my new anti freeze ??? HELP !!




  • mattmia2
    mattmia2 Member Posts: 9,850
    If you have manual or automatic vents at the high points you can, just let out air until you get to liquid and close the vent, otherwise you'll need some sort of pump cart or an improvised version thereof like a submersible pump in a bucket or trash can.
  • mattmia2
    mattmia2 Member Posts: 9,850
    This is what i rigged up with a pump I had laying around to fill my system, but it only holds about 5 gallons, you probably would want a bigger reservoir for your system volume.

  • Ctoilman
    Ctoilman Member Posts: 105
    Maybe just an air pocket in the circulator itself.  If so, slightly loosen the flange bolts until the air is burped out.  Not saying this is the correct way to purge, but saves you buying a pump and double-ended (washing machine) hose.  It's quick, it's dirty, but can/does work.
  • unclejohn
    unclejohn Member Posts: 1,833
    I have done that trick as well with good results. Some pumps have a bleed on the body looks like a big screw. Just losen it a smidge.
  • Rongold
    Rongold Member Posts: 21
    edited May 2021
    Ctoilman said:

    Maybe just an air pocket in the circulator itself.  If so, slightly loosen the flange bolts until the air is burped out.

    No, it's not that. My other 2 zones heat perfectly. It's the highest zone in the house that won't get hot. My playroom zone is about 4 feet above the boiler--That zone heats OK. The kitchen/living room/dining room zone is about 6 feet above the playroom--That zone heats OK too. The bedroom zone is about 5 feet above the kitchen zone, and that makes it about 15 feet above the boiler--That zone stays cold--No circulation at all. It worked perfectly before I replaced the anti freeze. The zone valve fully opens, but the circulator evidently can't push the liquid past the air blockage. I have 1 circulator pump and 3 zone valves.


  • dopey27177
    dopey27177 Member Posts: 887
    At the highest zone and convector you will need to cut into the pipe and install a quality hose cock to leave in permanently. That will be your manual bleed valve.

    Shut down boiler.
    Drain off pressure
    Cut into pipe
    Install a shut off valve on the supply and return side of the top floor zone
    Connect a water hose to the bleed valve
    Shut down the inlet and out let valve valves
    Open up the water supply to the system
    Go up to the top floor and open up the return valve and let water flow for a short time
    Repeat with the supply side.
    Make sure you only do one side at a time