We are proud owners of a 1907 home that had finned-tube baseboard heat installed in about 1955. Normally, it works fine, but recently certain rooms do not receive heat. There are three zones. The repairmen tell us that for most of the older part of the house, the finned-tubes are continuous, meaning that you cannot turn off heat to one room or it will shut the system down. However, I question their understanding of the system. For example, our bedroom, which is supposed to be the last room in the system, is not receiving any heat. That does not shut the system down. We have bled the tube coming in to the room and there is no air--only hot water. There does not seem to be any other bleeding outlet in the room. That makes me think that somehow our room is getting bypassed. Does this make any sense? Is there somewhere I can go to get really detailed information about such a system? What is wrong with our system?