Air Eliminator

I'm installing a Weil-McLAIN CGA-3,IT has--- cast iron sections with built-in Air Separator.Should I still install an Air Eliminator or is the Air separator all I need (I believe they are the same things).

Don't think they are the same thing...Spirovent sort of combs the microair bubbles out of the water as it passes. A top-hat air job (don't remember the name) accumulates bubbles since it is often the highest point. A SPirovent can be anywhere in the circuit and do its job as I understand it. Now, whether you need both, that is the question.