(1)
Fans for heating, ventilating and air-conditioning systems shall be located and installed so that their operation
(a)
does not adversely affect the draft required for proper operation of fuel-fired appliances, and
(b)
does not allow the air in the duct system to be contaminated by air or gases from the boiler room or furnace room.
(2)
Fans and associated air-handling equipment, such as air washers, filters and heating and cooling units, when installed on the roof or elsewhere outside the building, shall be of a type designed for outdoor use.