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Purge Air from Multi Zone Boiler

Hi, I have a gas boiler and am wondering how I should be purging air out of one of the circ pumps? It’s the only one not blowing hot air and this has happened before. Attached some pics. Appreciate any help. It’s hard to find a video of this unit / configuration. Thank you


  • TerrapinSuite
    TerrapinSuite Member Posts: 2
    still having this issue, any advice?
  • Jamie Hall
    Jamie Hall Member Posts: 23,565
    Each zone has to be power purged -- at least five gpm if not more -- individually. Not sure how to do that on your system, but I suspect that there are combinations of valves and drains which will allow you to do that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • hot_rod
    hot_rod Member Posts: 22,394
    You're close, may be missing one valve. That red hose bib valve on the right side of the boiler could be your purge for all zones, however there needs to be a valve to the left of it. I can't see all the return piping to the boiler connection, is there a valve somewhere in that 1-1/4 black pipe? Like the yellow handled one above the red handled hose bib?

    If so, shut off that return valve, close all the valves above the pumps, open one at a time, purge until bubbles stop. It can take 15 minutes or so on some zones. Shut off the purged one, move to the next. Open one zone iso flange at a time, purge from the red valve.

    If not, where the lower most black coupling is, should be a ball valve. A sawzall, union, valve, and some nipples could add one.

    Your fill valve has a fast fill function by lifting the lever on top.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream