I want to remove both radiators on the top (third) floor of my house. I have a closed (pressurised) heating system fired by a combi boiler, and I understand that I have to drain the system to do this. Given that the radiators in question are at the top of the house, and given the laws of gravity, would it be sufficient for me to partially drain the system, i.e. drain until just the top radiators I want to remove are empty, or doesn't it work like that? Thanks. Also, as I understand it I can cap the pipes with compression fittings after removal, is this easy to do? Does it require specialist tools?