Install the Spirovent® at the point of lowest solubility, which is the place in the system where the temperature is the highest and pressure the lowest. Note as well to always "pump away" from the expansion tank, never towards it.

Related Work

Unocal - Pacific Northwest, US
4" Spirovent® air eliminator being used to control foam in a bottling operation for transmission fluid and motor oil.
Kansas State University - Manhattan, KS
Following the installation of numerous smaller units on campus that met all expectations, a separator upgrade was proposed for the central plant.
Healthcare Gallery
Spirovent® and Spirotrap® separators are installed in hundreds of hospital and medical centers throughout North America.
Residential Gallery
Spirovent® remains the world class standard that others attempt to reach. Often copied but never equaled.