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

Cottey College - Nevada, MO
From the President's house to the power plant, to almost all buildings on campus, Spirovents have contributed to efficient system performance across the campus.
Mercy Medical Center - Des Moines, IA
High velocity 18" combination air eliminator and dirt separator.
Silence is Golden (Yellow) for Berners-Schober
“The pumps are much quieter as is the circulating water
Eastern Illinois University - Charleston, IL
After having tried numerous other methods, the first Spirovent was installed in Carman Hall to deal with a long history of no heat calls and clogging valves.