When you come to a boiler that only has the strainer/air out and one hose bib at the boiler, how would be the best way to get the air out of the lines on the second or third floors? I am refering to in floor but rads are the same issue. Some clowns around here are trying to save a couple pennies by not putting air-outs in.
I would install an air eliminator spirovent at the top of the boiler loop.
Also be aware of Directors Order FS-072-06-R4 - Here (http://hvactechgroup.com/files/order/fs072064.pdf)
If a hydronic system is installed and piped properly you should be able to bleed 99.9% of the air from you secondary pipimg in the basement. I have done startups on 10,000 sqft in-floor jobs that I never touched a manifold above the basement.