All units are factory packaged with operating controls, relief valves, burner and fuel train. Installation is made simple in that only service connections are needed to place in operation. Flexible burner systems are available for firing natural gas, LP gas, No.2 oil, heavy oil, or combinations. High density 2" mineral wool insulation assures lower radiant heat loss. In addition to meeting the requirements of UL, burner systems are optionally available to meet the requirements of FM, IRI, MILITARY and others.