Posted by jtown on February 08, 2000 at 10:35:28:
In Reply to: Main vents posted by Bob on February 08, 2000 at 09:25:08:
Your radiator vents can do it. The one above your Loop sounds like a main to me, it would be odd to have one on the header where it becomes the equalizer down to the loop. If you have a dry (water runs down it when steaming) return above the water line that drops down to the loop. Any vent in the basement is a main normally.