The ventilation heater will be type ii per mil-h-16235, which requires nonmagntic construction, non magnetic material, tube has 60 fins per ft.
A heat transferring unit utilizing a separate source of steam or hot water as the heat transfer medium. It consists of finned parallel tubes joined together by a header or headers and is designed for installation in the ducts of a forced air circulating system. It may be provided with a flanged outer casing to facilitate mounting of the unit in planned or existing duct work. Circulation of the heated air is achieved by use of a blower or fan not integral with the heating unit.
Classification: Air heaters and hot air distributors, not electrically heated, incorporating a motor-driven fan or blower, and parts thereof, of iron or steel
NSN 7035-01-057-5221
NSN 6220-01-194-7274
NSN 6150-00-548-9802
NSN 5998-01-377-6578
NSN 6320-01-089-9086
NSN 2925-00-247-6248
NSN 6105-01-051-5901
NSN 6610-01-193-8861
NSN 6645-00-574-9712
NSN 6105-01-433-8804
NSN 5905-01-360-1112
NSN 6620-00-269-5168