Hot water holds less dissolved air, so separators go where water is hottest and pressure lowest, usually on the boiler supply. Air scoops and other chamber designs slow the water so bubbles rise; microbubble separators use a mesh or coalescing element to collect bubbles too small to see. Removing air stops gurgling, air-bound terminals and the corrosion that oxygen feeds.
Put the air separator on the boiler supply ahead of the pump, and pipe the expansion tank right off the bottom of it.
Also heard as
- air eliminator
Related terms
Expansion tank
A closed tank with an air cushion that absorbs the expansion of heating water as it warms up.
Bleed
To let trapped air out of a hot water radiator, baseboard or high point by opening its small vent until water appears.
Point of no pressure change
The place in a closed hydronic loop, where the expansion tank connects, whose pressure the pump cannot change.
Primary-secondary
Describes hydronic piping where each circuit has its own pump and connects to a main loop through two closely spaced tees.