... on coal, heavy oil, light oil or flammable gas as fuel, steam boiler,hot water. Working principle: ... on coal, heavy oil, light oil or flammable gas as fuel, heat conducting oil as heat carrier. ... lower atmospheric pressure and can transport heat with liquid style. Temperature of heat carrier(300º C) ... boiler,hot water boiler Coal, Oil( Gas ) Fired Heaterthermal Boiler,steam boiler,hot water boiler