(1)
Return-air inlets shall not be installed in an enclosed room or crawl space that provides combustion air to a furnace.
(2)
Except for floor levels which are less than 900 mm above or below an adjacent floor level which is provided with a return-air inlet, at least one return-air inlet shall be provided in each floor level in a dwelling unit.
(3)
Provision shall be made for the return of air from all rooms by leaving gaps beneath doors, using louvred doors or installing return duct inlets.