(See Note A-9.32.3.5.)
(1)
Where outdoor air is to be introduced to the dwelling unit through means other than a forced air heating system, the provision of outdoor air shall comply with this Article.
(2)
An outdoor air supply fan shall be installed with a rated capacity within ±10% of the actual normal operating exhaust capacity of the exhaust fan installed to satisfy the requirement for a principal ventilation fan.
(3)
The principal ventilation fan control required by Sentence 9.32.3.3.(5) shall be wired in such a way that
(a)
activation of the principal ventilation fan automatically activates the outdoor air supply fan required by Sentence (2), and
(b)
the outdoor air supply fan does not operate when the principal ventilation fan is not operating.
(4)
The outdoor air supply fan shall be connected to the outdoors through an outdoor air supply duct.
(5)
The outdoor air supply duct required by Sentence (4) shall incorporate a flow-regulating damper.
(6)
With the principal ventilation fan operating at its normal operating exhaust capacity, the airflow in the outdoor air supply duct shall be measured and the flow-regulating damper required by Sentence (5) shall be adjusted and permanently fixed so that the airflow in the outdoor air supply duct is within ±10% of the actual normal operating exhaust capacity of the principal ventilation fan.
(7)
The airflow measurements required by Sentence (6) shall be done using a method accurate to within ±15% of the flow rate being measured.
(8)
Except where a heat recovery ventilator is used to supply the outdoor air, the outdoor air shall be tempered to at least 12°C before being circulated to habitable spaces.
(9)
Any tempering device installed to comply with Sentence (8) shall be installed in accordance with Articles 9.33.4.1. and 9.33.5.2.
(10)
Except as provided in Sentence (11), outdoor air shall be distributed by a system of trunk and branch supply ducts, from the outdoor air supply fan required by Sentence (2) to
(a)
each bedroom
(b)
any storey, including basements and heated crawl spaces, without a bedroom, and
(c)
if there is no storey without a bedroom, to the principal living area.
(11)
In a dwelling unit in which there is no storey without a bedroom, if an exhaust air intake for the principal ventilation fan is located in the principal living area and the principal ventilation fan has no more than 2 exhaust air intakes located in other rooms, distribution of outdoor air to the principal living area is not required.
(12)
All branch supply ducts that are not fitted with diffusers with adjustable balance stops shall be supplied with balancing dampers that
(a)
can be fixed in their adjusted positions, and
(b)
include devices to indicate the positions of the dampers.
(13)
The air supply outlets through which outdoor air is delivered to the rooms shall be located in the ceiling or in a wall at not less than 2 m above the floor and shall be designed and installed to promote diffusion across the ceiling.
(14)
Provision shall be made for the free flow of air to or from all rooms by leaving gaps beneath doors, using louvred doors or installing grilles in doors.