I was in a circa 1890 boarding house recently. Central heat with steam boiler(s), Utica circa 1978. I have not seen a set up like this before, it looks like two boilers with individual burners attached to each other as you would sections of a radiator. When tested only one side fired up. Is the other side to provide addtional heat should the one burner be inadequate or should both run together. There is only one thermostat, TPRV, low water cut off , etc. New to me, anyone familiar with this arrangment? Click to Enlarge 96.2 KB Click to Enlarge 46.66 KB