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1/8in vent in vertical riser
I bought a new house and there are two headers with 2 quick vents where they droo to wet returns and new vents on all radiators. Finally balanced system well.
but there was a hoffman 1a adjustable vent in a 2in riser that goes through a powder room to heat that room on its way to second floor rads. It had been turned aideways when someone remodeled bathroom and dropped ceiling and painted ten tines, so i cut in half, spun out, scraped to identify and decided I could put a variabalve in it since it seemed to be an adjustable vent.
at the end of heat cycle once in a while it seems to release a lot of pressure, like just spit air pretty loudly. Seems like system should not have that much pressure.
I am not sure it even should have a vent.