I bought an old farm house and has hot water convectors on the walls. These are marked National Art Convector, National Radiator Co. I know very little about them, they have "fins" that would remind me of a baseboard but a large metal cabinet. Can anyone tell me what the age of these is and any other info about them. I am thinking about going to old cast iron radiators in the house but would like to know more about these convectors. I have included a few pictures that may help.