The reason for the open tank in the attic was that when the system was filled, all the air in the pipes and radiators would flow to it and then be evacuated. The expansion tank would then fill with water and be a source to make up evaporation loss. If you put the tank in the basement, you will still need a reliable means of evacuating the air at the high point of the system, which is where the tank is now. Air will enter the system as new water is added and then heated. It will flow to the high point in the system and if it is not removed promptly, it will cause the heat to stop operating.: I have a gravity fed heating system in a 1908 house. 3 radiators on 2nd floor, 5 on first floor, boiler in basement. I would like to remove the open expansion tank that hangs on the wall in the bathroom on second floor. It is connected to the radiator and drains to the bathtub. Can I install a pressurized expansion tank in the basement? Is there some other solution to my problem?
