6.2.3.

(1) Except as provided in Sentence (2), this Subsection applies to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems.

(2) This Subsection does not apply to the design, construction and installation of air duct distribution systems serving heating, ventilating and air-conditioning systems that serve individual dwelling units within the scope of Part 9.

(1) Except as provided in Sentences (2) to (4) and in Article 3.6.4.3., all ducts, duct connectors, associated fittings and plenums used in air duct systems shall be constructed of steel, aluminum alloy, copper, clay, asbestos-cement or similar noncombustible material.

(2) Ducts, associated fittings and plenums are permitted to contain combustible material provided they,

(a) conform to the appropriate requirements for Class 1 duct materials in CAN/ULC-S110-M, “Test for Air Ducts”,

(b) conform to Article 3.1.5.15. in a building required to be of noncombustible construction,

(c) conform to Subsection 3.1.9.,

(d) are used only in horizontal runs in a building required to be of noncombustible construction,

(e) are not used in vertical runs serving more than 2 storeys in a building required to be of noncombustible construction, and

(f) are not used in air duct systems in which the air temperature may exceed 120°C.

(3) Duct sealants shall have a flame-spread rating of not more than 25 and a smoke developed classification of not more than 50.

(4) Duct connectors that contain combustible materials and that are used between ducts and air outlet units shall,

(a) conform to the appropriate requirements for Class 1 air duct materials in CAN/ULC-S110-M, “Test for Air Ducts”,

(b) be limited to 4 m in length,

(c) be used only in horizontal runs, and

(d) not penetrate required fire separations.

(5) Materials in Sentences (1) to (4) that when used in a location where they may be subjected to excessive moisture shall have no appreciable loss of strength when wet and shall be corrosion-resistant.

(6) All ductwork and fittings shall be constructed and installed in conformance with SMACNA Manuals and ASHRAE Handbooks.

(7) All duct materials and fittings shall be,

(a) suitable for exposure to the temperature and humidity of the air being conveyed, and

(b) resistant to corrosion due to contaminants in the air being conveyed in the duct.

(1) Air duct systems shall have,

(a) tight-fitting connections throughout, and

(b) no openings other than those required for proper operation, inspection and maintenance of the system.

(2) Access openings shall be provided in duct systems to allow the removal of material that may accumulate in plenums and ducts.

(1) Coverings, linings and associated adhesives and insulation of air ducts, plenums and other parts of air duct systems shall be of noncombustible material when exposed to heated air or radiation from heat sources that would result in the exposed surface exceeding a temperature of 120°C.

(2) When combustible coverings and linings, including associated adhesives and insulation, are used, they shall have a flame-spread rating of not more than 25 on any exposed surface or any surface that would be exposed by cutting through the material in any direction, and a smoke developed classification of not more than 50, except that the outer covering of ducts, plenums and other parts of air duct systems used within an assembly of combustible construction may have an exposed surface flame-spread rating of not more than 75 and may have a smoke developed classification greater than 50.

(3) Combustible coverings and linings in Sentence (2) shall not flame, glow, smoulder or smoke when tested in accordance with the method of test in ASTM C411, “Hot-Surface Performance of High-Temperature Thermal Insulation” at the maximum temperature to which the coverings and linings are to be exposed in service.

(4) Except as provided in Sentence (5), foamed plastic insulation shall not be used as part of an air duct or for insulating an air duct.

(5) Foamed plastic insulation may be used in a ceiling space that acts as a return air plenum provided the foamed plastic insulation is protected from exposure to the plenum in accordance with Article 3.1.5.12.v1v2

(6) Combustible coverings and linings of ducts, including associated adhesives and insulation, shall be interrupted at the immediate area of operation of heat sources in a duct system, such as electric resistance heaters or fuel-burning heaters or furnaces, and where the duct penetrates a fire separation.

(7) Linings of ducts shall be installed so that they will not interfere with the operation of volume or balancing dampers, fire dampers, fire stop flaps and other closures.

(1) Underground ducts shall,

(a) be constructed and installed with a slope to provide interior drainage to all low points,

(b) not be connected directly to a sewer, and

(c) be installed and constructed of materials in conformance with ASHRAE Handbooks, SMACNA Manuals and the HRAI Digest.

(2) A clean-out or pump-out connection shall be provided in an underground duct system at every low point of the duct system.

(1) Fire dampers shall conform to the requirements of Subsection 3.1.8.

(1) Air handling systems shall incorporate smoke detector control where required by Article 3.2.4.12.

(1) Except as provided in Sentence (2), exhaust ducts of nonmechanical ventilating systems serving separate rooms or spaces shall not be combined.

(2) Exhaust ducts of nonmechanical ventilating systems serving similar occupancies may be combined immediately below the point of final delivery to the outside, such as at the base of a roof ventilator.

(3) Exhaust ducts of ventilating systems shall have provision for the removal of condensation where this may be a problem.

(4) Exhaust outlets shall be designed to prevent back draft under wind conditions.

(5) Except as permitted in Sentence (6), exhaust systems shall discharge directly to the outdoors.

(6) Exhaust systems are permitted to exhaust into a storage garage, provided,

(a) they serve rooms that are accessible only from that storage garage,

(b) the exhaust contains no contaminants that would adversely affect the air quality in the storage garage, and

(c) they are designed in accordance with Sentence 6.2.3.9.(3)v1.

(7) Exhaust ducts connected to laundry drying equipment shall be,

(a) independent of other exhaust ducts,

(b) designed and installed so that the entire duct can be cleaned, and

(c) constructed of smooth corrosion-resistant material.

(8) Except as provided in Sentence (10) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing water closets, urinals, basins, showers or slop sinks shall be independent of other exhaust ducts.

(9) Except as provided in Sentence (10) and except for self-contained systems serving individual dwelling units, exhaust ducts serving rooms containing residential cooking equipment shall be independent of other exhaust ducts.

(10) Two or more exhaust systems described in Sentences (8) and (9) may be interconnected or connected with exhaust ducts serving other areas of the building provided,

(a) the connections are made at the inlet of an exhaust fan, and all interconnected systems are equipped with suitable back pressure devices to prevent passage of odours from one system to another when the fan is not in operation, or

(b) the exhaust ducts discharge to a shaft that is served by an exhaust fan having a capacity that is equal to or greater than the combined capacity of the exhaust fans discharging to the plenum multiplied by the operation diversity factor, provided that the exhaust fan serving the shaft operates continuously.

(11) Where exhaust ducts containing air from conditioned spaces pass through or are adjacent to unconditioned spaces, the ducts shall be constructed to prevent condensation from forming inside or outside of the ducts.

(12) Where an exhaust duct system is used for smoke removal in a high building, the requirements of Article 3.2.6.10. shall apply.

(13) Where exhaust duct systems from more than one fire compartment are connected to an exhaust duct in a vertical service space, the requirements of Article 3.6.4.3 shall apply.

(14) Except as provided in Sentence (15), exhaust air shall be provided at a rate not less than 24 L/s for each water closet, urinal, shower or slop sink.

(15) Exhaust air shall be provided for fixtures in dwelling units in accordance with ANSI/ASHRAE 62, “Ventilation for Acceptable Indoor Air Quality”.

(16) Except for wash basins (lavatories), sanitary facilities in a food premises shall be mechanically ventilated and shall be capable of exhausting air at the rate of not less than 24 L/s for each sanitary fixture listed in Sentence (17).

(17) The mechanical ventilation described in Sentence (16) applies to rooms containing water closets, urinals, basins, showers or slop sinks.

(1) In a residential occupancy, air from one suite shall not be circulated to any other suite or to a public corridor or public stairway.

(2) Except as permitted by Sentence (3) and Sentence 6.2.3.8.(6), air duct systems serving storage garages shall not be directly interconnected with other parts of the building.

(3) Exhaust ducts referred to in Sentence 6.2.3.8.(8) may exhaust through an enclosed storage garage prior to exhausting to the outdoors provided,

(a) the storage garage exhaust system runs continuously,

(b) the capacity of the storage garage exhaust system is equal to or exceeds the volume of the exhaust entering the garage, and

(c) a leakage rate 1 smoke/fire damper rated in accordance with CAN/ULC-S112.1-M, “Leakage Rated Dampers for Use in Smoke Control Systems”, is provided near the duct outlet location in the storage garage to prevent air from the storage garage from entering the exhaust ductwork system in the event the building’s exhaust fan is shut down.

(4) Except for Sentence 3.3.1.4.(4) and Sentences (5) and (6), a public corridor or corridor serving the public shall not be used as a portion of a supply, return or exhaust air system serving adjoining areas, other than as part of a supply air system serving toilet rooms, bathrooms, shower rooms and similar auxiliary spaces opening directly to the public corridor or corridor used by the public.

(5) A public corridor may be used as part of an engineered smoke control system.

(6) Infiltration due to corridor pressurization is permitted into a residential occupancy from a public corridor.

(1) Duct penetration of fire separations separating exits from the remainder of the building shall be in accordance with Article 3.4.4.4.v1

(1) In ventilating systems that exhaust air to the outdoors, provision shall be made for the admission of a supply of make-up air in sufficient quantity so that the operation of the exhaust system and other exhaust equipment or combustion equipment is not adversely affected.

(2) Make-up air facilities required by Sentence (1) shall be interlocked with the exhaust devices they serve so that both operate together.

(3) Where make-up air facilities are intended to introduce air directly from the outdoors to occupied parts of the building in winter, they shall incorporate means of tempering that air to maintain the indoor design temperature.

(1) Supply, return and exhaust air openings located less than 2 000 mm above the floor in rooms or spaces in buildings shall be protected by grilles having openings of a size that will not allow the passage of a 15 mm diameter sphere.

(2) Outdoor air intakes and exhaust outlets on the exterior of buildings shall be designed or located so that the air entering the building system will not contain more contaminants than the normal exterior air of the locality in which the building is situated.

(3) Exterior openings for outdoor air intakes and exhaust outlets shall be shielded from the entry of snow and rain and shall be fitted with corrosion-resistant screens of mesh having openings not larger than 15 mm, except where experience has shown that climatic conditions require larger openings to avoid icing over of the screen openings.

(4) Screens required in Sentence (3) shall be accessible for maintenance.

(5) Combustible grilles, diffusers and other devices for supply, return and exhaust air openings in rooms shall conform to the flame-spread rating and smoke developed classification requirements for the interior finish of the surface on which they are installed.

(1) Air filters for air duct systems shall conform to the requirements for Class 2 air filter units as described in CAN4-S111, “Fire Tests For Air Filter Units”.

(2) When electrostatic-type filters are used, they shall be installed so as to ensure that the electric circuit is automatically de-energized when filter access doors are opened and in dwelling units when the system circulating fan is not operating.

(3) When odour removal equipment of the adsorption type is used it shall be,

(a) installed to provide access so that adsorption material can be reactivated or renewed, and

(b) protected from dust accumulation by air filters installed on the inlet side.

(4) Facilities for flushing and drainage shall be provided where filters are designed to be washed in place.

(1) The filter and water evaporation medium of every air washer and evaporative cooling section enclosed within a building shall be made of noncombustible material.

(2) Sumps for air washer and evaporative cooling sections shall be constructed and installed so that they can be flushed and drained.

(3) Evaporative cooling sections or towers shall comply with the requirements of NFPA 214, “Water-Cooling Towers”.

(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 air 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.

(1) Vibration isolation connectors in air duct systems shall be noncombustible, except that combustible fabric connectors are permitted provided they,

(a) do not exceed 250 mm in length,

(b) comply with the flame-resistance requirements of CAN/ULC-S109, “Flame Tests of Flame-Resistant Fabrics and Films”, and

(c) are not used in a location where they are exposed to heated air or radiation from heat sources that may cause the exposed surface to exceed a temperature of 120°C.

(1) Tape used for sealing joints in air ducts, plenums and other parts of air duct systems shall meet the flame-resistance requirements for fabric in CAN/ULC-S109, “Flame Tests of Flame-Resistant Fabrics and Films”.

(1) Rectangular panels in plenums and ducts more than 300 mm wide shall be shaped to provide sufficient stiffness.

(2) Where the installation of heating supply ducts in walls and floors creates a space between the duct and construction material, the space shall be fire stopped with noncombustible material at each end.

(3) Ducts shall be securely supported by metal hangers, straps, lugs or brackets, except that where zero clearance is permitted, wooden brackets may be used.

(4) All round duct joints shall be tight-fitting and lapped not less than 25 mm.

(5) Rectangular duct connections shall be made with S and drive cleats or equivalent mechanical connections.

(6) Trunk supply ducts shall not be nailed directly to wood members.

(7) Branch ducts shall be supported at suitable spacings to maintain alignment and prevent sagging.

(8) Ducts in or beneath concrete slabs-on-ground shall be watertight, corrosion-, decay- and mildew-resistant.

(9) Where a supply or return duct is not protected by an insulated exterior wall or where the duct is exposed to an unheated space it shall be insulated to prevent condensation.

(1) The clearances from combustible material and supply plenums, supply ducts, boots and register boxes of heating systems shall conform to the requirements of Subsection 6.2.4.

(1) The return-air system shall be designed to handle the entire air supply.

(2) Where any part of a return duct will be exposed to radiation from the furnace heat exchanger or other radiating part within the furnace, such part of a return duct directly above or within 600 mm of the outside furnace casing shall be noncombustible.

(3) Return ducts serving solid fuel-fired furnaces shall be constructed of noncombustible material.

(4) Where combustible return ducts are permitted, they shall be lined with noncombustible material below floor registers, at the bottom of vertical ducts and under furnaces having a bottom return.

(5) The return-air system shall be designed so that the negative pressure from the circulating fan cannot affect the furnace combustion air supply nor draw combustion products from joints or openings in the furnace or flue pipe.

(6) Return-air inlets shall not be installed in an enclosed room or crawl space that provides combustion air to a fuel-fired appliance.