Notes to Table 9.32.3.5.:
9.32.3.7. Ventilation Systems Not Coupled with Forced Air Heating Systems (1) This Article applies to a mechanical ventilation system in a dwelling unit that, (a) does not contain a forced air heating system, or (b) contains a forced air heating system which is not used for circulation of the ventilation air. (2) The mechanical ventilation system shall introduce air to and circulate air throughout the dwelling unit in compliance with this Article. (3) The mechanical system in this Article shall include a heat recovery ventilator installed in accordance with Article 9.32.3.11. (4) Outdoor air shall be distributed by a ductwork system from the heat recovery ventilator required in Sentence (3) to each bedroom, to any storey
without a bedroom and, if there is no storey
without a bedroom, to the principal living area. (5) A
supply duct from the outdoors to the heat recovery ventilator required in Sentence (3) and a main distribution trunk duct shall be provided and shall be sized according to Part 6, except that the supply duct and the main distribution trunk duct may be sized according to Table 9.32.3.7.A. where, (a) the total duct length from the outdoor hood to any supply register does not exceed 21 m, and (b) the total number of fittings does not exceed 8. Table 9.32.3.7.A.   Minimum Outdoor Air Supply and Main Trunk Duct Sizes Forming Part of Sentence 9.32.3.7.(5) Item   Column 1 Number of Bedrooms in Dwelling Unit   Column 2 Minimum Outdoor Air Supply and Main Distribution Trunk Duct Diameter, mm 

  1.   1   150 

  2.   2   150 

  3.   3   175 

  4.   4   175 

  5.   5   175 

  6.   More than 5   System must comply with Sentence 6.2.1.1.(1) (6) The outside air supply duct required by Sentence (5) shall not be considered to provide combustion and/or dilution air to fuel-burning appliances. (7) Branch
supply ducts leading from the main distribution trunk duct required by Sentence (5) to the rooms to which outdoor air is to be distributed shall be provided and shall be sized according to Part 6, except that the branch supply ducts may be sized according to Table 9.32.3.7.B. where, (a) the total duct length from the outdoor hood to any supply register does not exceed 21 m, and (b) the total number of fittings does not exceed 8. Table 9.32.3.7.B.   Minimum Branch Supply Duct Sizes Forming Part of Sentence 9.32.3.7.(7) Item   Column 1   Column 2   Column 3 

      Room, Space or Storey Served   Minimum Branch Supply Duct Diameter, mm 

      1 and 2 Bedroom Dwelling Units   3, 4 and 5 Bedroom Dwelling Units 

  1.   Master bedroom   100   100 

  2.   Other bedrooms   75   75 

  3.   Storey with no bedrooms or living area   75   100 (8) In applying Sentence (7), where the dwelling unit has more than 5 bedrooms, ducting shall be sized according to Part 6. (9) All branch supply ducts that are not fitted with diffusers with adjustable balance stops shall be supplied with accessible dampers that can be adjusted and fixed in their adjusted positions and that include devices to indicate the positions of the dampers. (10) Provision shall be made for the free flow of air to all rooms by leaving gaps beneath doors, using louvred doors or installing grilles in doors.