This is an issue we see in so many buildings. We come to a building where the bills are very high and yet half the building has no heat. When we walk through the building we find that the headers are being vented with one tiny radiator air vent. Venting is a science like any other aspect of heating. There are calculations that need to be performed to figure out how much venting is required and correct locations for these air vents to be placed. Below are a few pictures of vents in a building.

Venting Headers: