About Air Eliminators
While terms “air eliminator” and “air separator” are often used interchangeably and some manufacturers prefer one term over the other, they are both used to indicate a device which collects and eliminates the air from the water in a heating or cooling system.
When air is present in a hydronic heating system, it causes faster aging of cast iron components and leads to formation of air gaps. Rust in the water lowers its’ heat transfer ability and therefore reduces the overall efficiency of the heating system, leading to higher operating costs. The sediment further accumulates on various system components and results in their frequent maintenance and early failure. When air molecules accumulate into bubbles, they forms air gaps which often create irritating noise and further reduce efficiency of the system.
How it works
When oxygen-rich (aerated) water enters the main chamber of the air eliminator through the piping inlet, the water flow is slowed down and the air is “scrubbed” from it utilizing product-specific design. The air bubbles then slowly rise to the top of the main chamber (called “collection chamber”), where they accumulate. As air accumulates in the collection chamber, it pushes the water level down and with it - the float which controls the air release valve. Once threshold level is reached, the float type air vent opens and vents out the air. The float returns to its’ normal position and the process repeats.
Most manufacturers recommend installing the air elimination device on a supply line in close proximity to the boiler, where air volume is the highest and easiest to collect and eliminate. A typical air eliminator, including Taco and Spirotherm brands available at PexUniverse include a 1/2" female NPT threaded bottom tapping which allows to connect an expansion tank and is also the best location for a fresh water supply inlet.
Majority of air eliminators on the market are for horizontal pipe runs only, however, Spirotherm also produces models for vertical piping installations.
Spirovent Air Eliminators by SpirothermSpirovent Jr series eliminators
are among the best and most popular on the market and come in a large variety of horizontal and vertical models with connection sizes up to 1-1/2". These units offer 100% elimination of free and entrained air and up to 99.6% elimination of dissolved air. Spirovent junior series are made from solid brass, rated up to 150 psi at 270°F and come with an unmatched 20-year manufacturers warranty. For optimal performance, they should be installed in a combination with a Spirotop air vent and Spirotrap dirt separator.
Taco 4900 Air Separators
The 4900 series Taco air separator
is a top of the line unit designed to eliminate air bubbles in size down to 15 micron, which is 3 times better then comparable models from other manufacturers. Conical shape of the collection chamber reduces chances of fouling to a minimum, while patented PALL rings allow for high flow rates with relatively low pressure drop. These air separators are rated 150 psi at 240°F.
Taco Vortech Air Separators
Special design of the Vortech air separator
creates a vortex effect with a low pressure center to which the air is drawn and is eliminated using a factory-installed, replaceable 3/4" Taco Hy-Vent. These units are made from cast iron and rated 150 psi at 240°F. Vortech series is a lower-priced alternative to 4900 series with reduced Cv values.
Taco Air Scoops
A cast iron scoop
is a one-piece cast iron device with a large internal chamber, which slows down the water flow and allows the larger air bubbles to rise to the top of the chamber, where air vent (not included) eliminates the air. Taco air scoops are maintenance-free and are rated 125 psi at 300°F.
These units can replace similar air purgers made by Honeywell.
Spirotrap Dirt Separators
Designed and manufactured by Spirotherm, these dirt separators allow to filter out sediment in water down to 5 microns in size and are recommended mostly for hydronic heating systems containing cast iron radiators or large amount of cast iron components. Each dirt separator has a dirt collection chamber with a mini ball valve and a garden hose threaded outlet for quick purging of the accumulated dirt.