Ok so right now we have no heat to the second floor. Circulator pump is running. There is hot water and the furnace is firing as it should be. The hot water pipes up to the second floor are cold even with the circulator pump running. We tried to bleed the air from the system but no air or water came out. First floor has heat. It seems as though the system is not filling. My brother took three years of HVAC at a tech school during high school and he has no clue. This system was installed sometime in the 80s I think. If you want I can get you pics but it would have to wait until tomorrow. Thank you in advance for your time.