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Air in the system

Hello all, a few questions from a heating novice. My brother just bought a new home and I was over there last weekend helping him move some stuff in. It's a two story home with baseboard heat. While I was over there we had the heat on and the heat on the first floor was working great but the heat upstairs didn't seem to be working well at all. So we decided to purge that zone to see if air in the system was the problem, that must have been it because after we purged it out it started working great. It's a zone valve system with three zones, basement, first floor, second floor. My question is there's a Spirovent and I'm wondering if they ever go bad or need to be cleaned? Also, the pressure gauge says the system is running at 12psi right now, does that seem right? Should the auto fill valve, expansion tank, and boiler pressure(?) all be set to the same psi? We're not going to cut into the system and replace an air separator but I figured if they're easy to clean maybe we could tackle that. Thanks in advance for any input.


  • GBart
    GBart Member Posts: 746
    12 psi should be correct unless it's very high ceilings from the basement up, Spirovents rarely go bad, any air would go to the upper floor, could be the exp tank diaphragm is starting to leak (air) into the system, if so the pressure on the boiler will rise when the burner runs at some point, it only takes a little air bubble to kill upper floor water flow, they aren't positive displacement pumps, they're centrifugal circulators with little HP.
  • Northwoods
    Northwoods Member Posts: 5
    Ok, that makes sense. The basement ceiling height seems to be a standard 8', maybe slightly less. There is 9' ceilings on the first floor though
    JUGHNE Member Posts: 11,075
    Any auto air vent has to have the air pass thru it via water flow.
    Once you establish the water flow then any excess air bubbles should leave thru the auto vent. IMO