Air elimination devices remove air bubbles from hydronic heating systems before the air can cause any disturbances. Air in a system can cause noise and block heat distribution. Traditional air vents needed to be installed at the highest point in a system in order to function properly. Air scoops, which connect to air vents, can be mounted at the boiler. They use baffles to direct air bubbles to the vent, and they require a minimum of 18 inches of straight pipe prior to the inlet. Spirotherm pioneered an even more effective air elimination device with the introduction of the Spirovent. Requiring no added vents, Spirovent air eliminators use a patented Spirotube core to remove more air than air scoops — with no inlet pipe requirement.
Air eliminators work best when system fluid is as hot as possible and moving at its lowest velocity. As a result, they should normally be installed near the boiler outlet and before the circulator pump. Generally, an air eliminator that matches the size of the supply and return piping will be installed. Most air eliminators, however, should really be sized based on the flow rate of the liquid in the system. 3/4” Spirovent air eliminators, for example, can handle up to 6 gallons per minute (GPM). 1” models are compatible with 10 GPM, and 1-1/4” range up to 15 GPM. Requirements differ by manufacturer and water velocity.