I have a forced hot water system and I can't get any water to the second floor. I opened the bleeder valves on the base boards and a little air comes out but not much. My pressure is set at 22 and from the basement to the 2nd floor the distance is about 19'. I followed the supply pipe and noted where the branch goes to the second floor. About 2' from where the branch comes off the supply, the pipe is hot then there is a drain valve and shortly after the pipe is not hot and likely waterless. I have tried combinations of shutting the boiler off, shutting the water supply off, draining but still can't get water/heat to the 2nd floor. Thoughts?