OBC DIVISION B · PART 9 — HOUSING AND SMALL BUILDINGSUpdated for the 2024 Ontario Building Code
Try BUILDAiD Beta
Section 9.33 — Heating and Air-Conditioning
Full text of Section 9.33 (Heating and Air-Conditioning) — Division B, Part 9 (Housing and Small Buildings) of the 2024 Ontario Building Code, with every article reproduced below.
On this page:
9.33.1.1.9.33.2.1.9.33.3.1.9.33.3.2.9.33.4.1.9.33.4.2.9.33.4.3.9.33.4.4.9.33.4.5.9.33.4.6.9.33.4.7.9.33.4.8.9.33.4.9.9.33.5.1.9.33.5.2.9.33.5.3.9.33.5.4.9.33.6.1.9.33.6.2.9.33.6.3.9.33.6.4.9.33.6.5.9.33.6.6.9.33.6.7.9.33.6.8.9.33.6.9.9.33.6.10.9.33.6.10A.9.33.6.11.9.33.6.12.9.33.6.13.9.33.6.14.9.33.6.14A.9.33.7.1.9.33.7.2.9.33.8.1.9.33.8.2.9.33.8.3.9.33.8.4.9.33.9.1.9.33.10.1.9.33.10.2.9.33.10.3.
9.33.1.1.9.33.2.1.9.33.3.1.9.33.3.2.9.33.4.1.9.33.4.2.9.33.4.3.9.33.4.4.9.33.4.5.9.33.4.6.9.33.4.7.9.33.4.8.9.33.4.9.9.33.5.1.9.33.5.2.9.33.5.3.9.33.5.4.9.33.6.1.9.33.6.2.9.33.6.3.9.33.6.4.9.33.6.5.9.33.6.6.9.33.6.7.9.33.6.8.9.33.6.9.9.33.6.10.9.33.6.10A.9.33.6.11.9.33.6.12.9.33.6.13.9.33.6.14.9.33.6.14A.9.33.7.1.9.33.7.2.9.33.8.1.9.33.8.2.9.33.8.3.9.33.8.4.9.33.9.1.9.33.10.1.9.33.10.2.9.33.10.3.
9.33.1.General
9.33.1.1.Application permalink →
(1) This Section applies to the design and installation of
(a) heating systems, including requirements for combustion air, and air-conditioning systems serving only one dwelling
unit, and
(b) radiant heating systems in houses with a secondary suite including their common spaces.
(2) The design and installation of heating systems, including requirements for combustion air, and air-conditioning
systems other than those described in Sentence (1) shall conform to Part 6. (See Note A-9.33.1.1.(2) and Subsection
9.10.10.)
(2.1) Repairs or component replacements that change the capacity or extent of safety of an existing heating, ventilating or
air-conditioning system and that alter the method of operation shall conform to this Code.
(3) Air duct distribution systems serving one of the dwelling units in a house with a secondary suite shall not be directly
interconnected with other parts of the house.
9.33.2.Required Heating Systems
9.33.2.1.Residential Heating Systems permalink →
(1) Residential buildings intended for use in the winter months on a continuing basis shall be equipped with heating
facilities conforming to this Section.
9.33.3.Design Temperatures
9.33.3.1.Indoor Design Temperatures permalink →
(1) At the outside design temperature, required heating facilities shall be capable of maintaining an indoor air
temperature of not less than
(a) 22°C in all living spaces,
(b) 18°C in unfinished basements,
(c) 18°C in common service rooms, ancillary spaces and exits in houses with a secondary suite, and
(d) 15°C in heated crawl spaces.
9.33.3.2.Outdoor Design Temperatures permalink →
(1) The outdoor conditions to be used in designing heating, ventilating and air-conditioning systems shall be the
appropriate values for the location as set out in MMAH Supplementary Standard SB-1, “Climatic and Seismic Data,”
using 2.5 percent design temperature criteria.
9.33.4.General Requirements for Heating and Air-Conditioning
9.33.4.1.Design of Heating and Air-Conditioning Systems permalink →
(1) Heating, ventilating and air-conditioning systems, including related mechanical refrigeration systems, shall be
designed, constructed and installed to conform to good engineering practice appropriate to the circumstances such as
described in
(a) the ASHRAE Handbooks and Standards,
(b) CSA F280, “Determining the required capacity of residential space heating and cooling appliances,” and the outside
winter design temperatures shall conform to MMAH Supplementary Standard SB-1, “Climatic and Seismic Data,”
(c) CAN/CSA-F326-M, “Residential Mechanical Ventilation Systems,”
r1 (d) the NFPA Standards,
(e) the HRAI Digest,
(f) the Hydronics Institute Manuals, and
(g) the SMACNA Manuals.
(See also Subsection 9.32.3. for the design of systems that also provide ventilation.)
9.33.4.2.Installation of Hydronic Heating Systems permalink →
(1) The design and installation of hydronic heating systems shall conform to
(a) CSA B214, “Installation code for hydronic heating systems”, or
(b) good engineering practice appropriate to the circumstances such as described in Article 9.33.4.1.
9.33.4.3.Heating System Control permalink →
(1) Each dwelling unit shall be provided with a temperature control in accordance with Article 12.3.1.3. (See Note A-
9.33.4.3.(1))
9.33.4.4.Access permalink →
(1) Equipment forming part of a heating or air-conditioning system, with the exception of embedded pipes or ducts,
shall be installed with provision for access for inspection, maintenance, repair and cleaning.
9.33.4.5.Protection from Freezing permalink →
(1) Equipment forming part of a heating or air-conditioning system that may be adversely affected by freezing
temperatures and that is located in an unheated area shall be protected from freezing.
9.33.4.6.Expansion, Contraction and System Pressure permalink →
(1) Heating and cooling systems shall be designed to allow for expansion and contraction of the heat transfer fluid and
to maintain the system pressure within the rated working pressure limits of all components of the system.
9.33.4.7.Structural Movement permalink →
(1) Mechanical systems and equipment shall be designed and installed to accommodate the maximum amount of
structural movement provided for in the construction of the building.
(2) Where the building is in a location where the spectral acceleration, Sa(0.2), is greater than 0.55, heating and air-
conditioning equipment with fuel or power connections shall be secured to the structure to resist overturning and
displacement. (See Note A-9.31.6.2.(3))
9.33.4.8.Asbestos permalink →
(1) Asbestos shall not be used in air distribution systems or equipment.
9.33.4.9.Contaminant Transfer permalink →
(1) Systems serving garages, and systems serving other occupied parts of a dwelling unit but located in or running
through a garage, shall be designed and constructed in a manner such that means are not provided for the transfer of
contaminants from the garage into other spaces in the dwelling unit.
9.33.5.Heating and Air-Conditioning Appliances and Equipment
9.33.5.1.Capacity of Heating Appliances permalink →
(1) The heating system capacity shall be based on the heating load calculated in accordance with Sentence 9.33.4.1.(1).
(2) Where a cooling system is installed, the cooling system capacity shall be based on the cooling load calculated in
accordance with Sentence 9.33.4.1.(1).
(3) The oversizing and undersizing of heating and cooling equipment capacities shall be determined in accordance with
the requirements of CSA F280, “Determining the required capacity of residential space heating and cooling appliances.”
9.33.5.2.Installation Standards (See also Article 9.33.5.3.) permalink →
(1) The design and installation of earth energy systems shall conform to CAN/CSA-C448.2, “Design and installation of
earth energy systems for residential and other small buildings,” where such systems use groundwater, submerged heat
exchangers or ground heat exchangers to serve,
(a) a house with or without a secondary unit, or,
(b) a building, a house with or without a secondary unit, where the conditioned space is not more than 1 400 m².
(2) Except for a house with or without a secondary unit, the design and installation of earth energy systems shall
conform to CAN/CSA-C448.1, “Design and installation of earth energy systems for commercial and institutional
buildings,” where such systems use groundwater, submerged heat exchangers or ground heat exchangers to condition a
floor space area more than 1 400 m².
9.33.5.3.Design, Construction and Installation Standard for Solid-Fuel-Burning permalink →
Appliances
(1) The design, construction and installation, including the provision of combustion air, of solid-fuel-burning appliances
and equipment, including stoves, cooktops, ovens and space heaters, shall conform to CSA B365, “Installation Code for
Solid-Fuel-Burning Appliances and Equipment.” (See Note A-9.33.5.3.(1))
(2) Solid fuel-burning stoves, furnaces and hydronic heating systems designed to burn solid fuels, other than coal, shall
conform to the particulate emission limits of,
(a) CSA B415.1, “Performance Testing of Solid-Fuel-Burning Heating Appliances”, or
(b) the “Standards of Performance for New Residential Wood Heaters”, set out in Subpart AAA of Part 60 of Title 40 of
the Code of Federal Regulations, published by the United States Environmental Protection Agency, as it read on
March 16, 2015.
(See Note A-9.33.5.3.(2))
9.33.5.4.Fireplaces permalink →
(1) Fireplaces shall conform to Section 9.22.
9.33.6.Air Duct Systems
9.33.6.1.Application permalink →
(1) The requirements of this Subsection apply to the design, construction and installation of air duct distribution systems
serving heating, ventilating and air-conditioning systems that serve an individual dwelling unit within the scope of Part 9.
(2) Air duct distribution systems in which the rated heat input exceeds 120 kW shall conform to Part 6 and Subsection
3.6.5.
9.33.6.2.Materials in Air Duct Systems permalink →
(1) Except as provided in Sentences (2) to (6.2) 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 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, “Standard Methods of Test
for Air Ducts,”
(b) conform to Article 3.1.5.18. and Subsection 3.1.9.,
(c) are not used in vertical runs serving more than 2 storeys, and
(d) 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, “Standard Methods of
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) Combustible ducts that are part of a duct system carrying only ventilation air and that are contained entirely within a
dwelling unit need not comply with the requirements of Sentences (1) to (4).
(6) Except as provided in Sentences 9.33.6.13.(2) and (3), ducts that are part of a return-air duct system and that are
contained entirely within a dwelling unit need not comply with the requirements of Sentences (1) to (4).
(6.1) All ductwork and fittings shall be constructed and installed in conformance with SMACNA Manuals and ASHRAE
Handbooks.
(6.2) 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.
(7) Materials referred to in Sentences (1) to (6.2), when used in a location where they may be subjected to excessive
moisture, shall
(a) have no appreciable loss of strength when wet, and
(b) be corrosion-resistant
9.33.6.3.Tape permalink →
(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, “Standard Method for Flame Tests of Flame-Resistant Fabrics and Films.”
9.33.6.4.Coverings, Linings and Insulation permalink →
(1) Reserved.
(2) Reserved.
(3) Reserved.
(4) Reserved.
(5) Except as permitted in Sentences (6) and (7), foamed plastic insulation shall not be used as part of an air duct or for
insulating an air duct.
(6) Foamed plastic insulation conforming to Article 9.25.2.2. is permitted to be used to insulate a galvanized steel,
stainless steel or aluminum air duct, provided
(a) the foamed plastic insulation applied to supply ductwork is not less than 3 m from the furnace bonnet,
(b) the temperature within the ductwork where the insulation is installed is not greater than 50°C,
(c) duct joints are taped with a product conforming to Sentence 9.33.6.3.(1),
(d) return air plenums are separated from the foamed plastic insulation, and
(e) the foamed plastic insulation is protected in accordance with Article 9.10.17.10.
(7) Foamed plastic insulation is permitted to 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 Sentence 3.1.5.14.(4).
(8) Reserved.
(9) Linings of ducts shall be installed so that they will not interfere with the operation of volume or balancing dampers
or of fire dampers, fire stop flaps and other closures.
9.33.6.5.Galvanized Steel or Aluminum Supply Ducts permalink →
(1) Galvanized steel or aluminum supply ducts shall conform to Table 9.33.6.5.
(2) The design of fittings for ducts shall conform to ANSI/SMACNA 006, “HVAC Duct Construction Standards –
Metal and Flexible,” except that metal thicknesses shall conform to Table 9.33.6.5.
Table 9.33.6.5.
Minimum Metal Thickness of Ducts
Forming Part of Article 9.33.6.5.
Minimum Metal Thickness, mm
Maximum Maximum Width
Type of Duct Duct Material
Diameter, mm or Depth, mm
Galvanized Steel Aluminum
Round ducts serving single dwelling units 125 or less — 0.254 0.30
350 — 0.33 0.30
Round
over 350 — 0.41 0.41
— 350 0.33 0.30
Rectangular, enclosed
— over 350 0.41 0.41
Rectangular, not enclosed, with required clearance up to — 350 0.33 0.41
12 mm — over 350 0.41 0.48
Rectangular, not enclosed, with required clearance of — 350 0.41 0.41
more than 12 mm — over 350 0.48 0.48
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
9.33.6.6.Construction of Ducts and Plenums permalink →
(1) Where the installation of heating supply ducts in walls and floors creates a space between the duct and construction
material, the space shall be firestopped with noncombustible material at each end.
(2) Ducts shall be securely supported by metal hangers, straps, lugs or brackets, except that, where zero clearance is
permitted, wooden brackets are permitted to be used.
(3) All round duct joints shall be tight-fitting and lapped not less than 25 mm.
(4) Rectangular duct connections shall be made with S and drive cleats or equivalent mechanical connections.
(4.1) Rectangular panels in plenums and ducts more than 300 mm wide shall be shaped to provide sufficient stiffness.
(5) Duct systems shall have no openings other than those required for the proper operation and maintenance of the
system.
9.33.6.7.Installation of Ducts and Plenums permalink →
(1) Air duct systems serving garages shall not be interconnected with other parts of the dwelling unit.
(2) Trunk supply ducts shall not be nailed directly to wood members.
(3) Branch ducts shall be supported at suitable spacings to maintain alignment and prevent sagging.
(4) Ducts passing through unheated spaces shall have all joints taped or otherwise sealed to ensure that the ducts are
airtight throughout their length.
(5) Combustible ducts in concrete slabs-on-ground that are connected to a furnace supply plenum shall be located not
closer than 600 mm to that plenum and not less than 600 mm from its connection to a riser or register.
(6) Ducts in or beneath concrete slabs-on-ground shall be watertight and corrosion-, decay-, and mildew-resistant.
(7) Underground ducts shall
(a) be constructed to provide interior drainage from and access 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.
(8) Where a supply duct 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 provide a thermal resistance of not less than RSI 2.1.
(9) Where a supply duct or return duct is located in an unconditioned space or outdoors, all joints of the ductwork shall
be sealed to a Class A seal level in accordance with the SMACNA, “HVAC Duct Construction Standards – Metal and
Flexible”.
(10) Where a supply duct is located in a conditioned space, the ductwork shall be sealed to a Class C seal level in
accordance with the SMACNA, “HVAC Duct Construction Standards – Metal and Flexible”.
(11) A clean-out or pump-out connection shall be provided in an underground duct system at every low point of the duct
system.
9.33.6.8.Clearances of Ducts and Plenums permalink →
(1) Reserved.
(2) Where the plenum clearance is 75 mm or less, the clearance between a supply duct and combustible material shall
(a) be equal to the required plenum clearance within 450 mm of the plenum, and
(b) be not less than 12 mm at a distance of 450 mm or more from the plenum, except that this clearance may be reduced
to zero beyond a bend or offset in the duct sufficiently large to shield the remainder of the supply duct from direct
radiation from the furnace heat exchanger.
(See Note A-3.6.5.6.(2))
(3) Where the plenum clearance is more than 75 mm but not more than 150 mm, the clearance between a supply duct
and combustible material shall be
(a) equal to the required plenum clearance within a horizontal distance of 1.8 m of the plenum, and
(b) not less than 12 mm at a horizontal distance of 1.8 m or more from the plenum, except that this distance may be
reduced to zero beyond a bend or offset in the duct sufficiently large to shield the remainder of the duct from direct
radiation from the furnace heat exchanger.
(See Note A-3.6.5.6.(3))
(4) Where the plenum clearance is more than 150 mm, the clearance between a supply duct and combustible material
shall be
(a) equal to the required plenum clearance within a horizontal distance of 1 m of the plenum,
(b) not less than 150 mm within a horizontal distance between 1 m and 1.8 m from the plenum, and
(c) not less than 25 mm at a horizontal distance of 1.8 m or more from the plenum, except that this distance may be
reduced to 8 mm beyond a bend or offset in the duct sufficiently large to shield the remainder of the supply duct
from direct radiation from the furnace heat exchanger.
(See Note A-3.6.5.6.(4))
(5) Where a register is installed in a floor directly over a pipeless furnace, a double-walled register box with not less
than 100 mm between walls, or a register box with the warm-air passage completely surrounded by the cold-air passage,
shall be permitted in lieu of the clearances listed in Sentences (2) to (4).
9.33.6.9.Adjustable Dampers and Balance Stops permalink →
(1) All branch supply ducts for residential systems shall be equipped with volume control dampers at the boot to permit
balancing or shall be fitted with a diffuser incorporating an adjustable and lockable volume control device that can be set
in a fixed position.
9.33.6.10.Warm-Air Supply Outlets and Return Inlets — General permalink →
(1) Reserved.
(2) Combustible grilles, diffusers and other devices for the supply and return air openings installed in walls and ceilings
shall have a flame-spread rating of
(a) not more than 200 in bathrooms, and
(b) not more than 150 in rooms or spaces other than bathrooms.
9.33.6.10A.Supply, Return, Intake and Exhaust Openings permalink →
(1) Supply, return and exhaust air openings in rooms or spaces 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 at the building exterior shall be designed or located so that the air entering
the building system will not contain more contaminants than the normal exterior air.
(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 climatic
conditions may require larger openings.
(4) Screens required in Sentence (3) shall be accessible for maintenance.
9.33.6.11.Warm-Air Supply Outlets permalink →
(1) In a dwelling unit, a warm-air supply outlet shall be provided in each finished room that is located adjacent to
unheated space.
(2) Except as provided in Sentence (3), when a room described in Sentence (1) is located adjacent to exterior walls, such
outlet shall be located so as to bathe at least one exterior wall or window with warm air, except in bathrooms, utility
rooms or kitchens, where this may not be practical.
(3) Where the heating system is also designed to provide ventilation air, ceiling outlets or outlets located high on
interior walls are permitted to be installed, provided the outlets are designed for this purpose and are installed with
diffusers.
(4) At least one warm-air supply outlet shall be provided for each 40 m 2 of floor surface area in unfinished basements
serving dwelling units, and it shall be located so as to provide adequate distribution of warm air throughout the basement.
(5) At least one warm-air supply outlet shall be provided for each 80 m 2 of floor surface area in heated crawl spaces
serving dwelling units, and it shall be located so as to provide adequate distribution of warm air throughout the crawl
space.
(6) Except for pipeless furnaces and floor furnaces, the capacity of warm-air supply outlets serving dwelling units shall
be not less than the design heat loss from the area served and shall not exceed 3 kW per outlet.
(7) In basements and heated crawl spaces, the calculated heat gain from the supply ducts and plenum surfaces is
permitted to be considered in calculating the design heat loss.
(8) The temperature of supply air at warm-air supply outlets shall not exceed 70°C.
(9) Warm-air supply outlets located in finished areas shall be provided with diffusers and adjustable openings and shall
not be located on a furnace plenum.
(10) Air duct systems serving storage garages shall not be interconnected with other parts of the building.
9.33.6.12.Return-Air Inlets permalink →
(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.
9.33.6.13.Return-Air System (See Note A-9.33.6.13.) permalink →
(1) The return-air system shall be designed to handle the entire air supply.
(1.1) Except as provided in Sentences (2) and (3), return ducts shall be constructed of material having a surface flame-
spread rating of not more than 150.
(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-burning furnaces shall be constructed of noncombustible material.
(4) Combustible return ducts shall be lined with noncombustible material
(a) below floor registers,
(b) at the bottom of vertical ducts, and
(c) under furnaces having a bottom return.
(5) Spaces between studs or joists used as return ducts shall be separated from the unused portions of such spaces by
tight-fitting metal stops or wood blocking.
(6) A vertical return duct shall have openings to return air on not more than one floor.
(6.1) A public corridor shall comply with Sentences 6.3.2.7.(4) and (5).
(7) The return-air system shall be designed so that the negative pressure from the circulating fan cannot
(a) affect the furnace combustion air supply, nor
(b) draw combustion products from joints or openings in the furnace or flue pipe.
(7.1) Return-air from a dwelling unit shall not be recirculated to any other dwelling unit.
9.33.6.14.Filters and Odour Removal Equipment permalink →
(1) Air filters for air duct systems shall conform to the requirements for Class 2 air filter units as described in
CAN/ULC-S111, “Standard Method of 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 or, in dwelling units, when the furnace circulation 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.
9.33.6.14A.Exhaust Ducts and Outlets permalink →
(1) Where an exhaust duct passes through or is adjacent to unheated space, the duct shall be insulated to prevent
moisture or condensation in the duct.
(2) Exhaust outlets shall be designed to prevent back draft under wind conditions.
(3) Exhaust ducts directly connected to laundry drying equipment shall be independent of other exhaust ducts.
(4) Exhaust systems shall discharge directly to the outdoors.
9.33.7.Radiators and Convectors
9.33.7.1.Recessed Radiators and Convectors permalink →
(1) Every steam or hot water radiator and convector located in a recess or concealed space or attached to the face of a
wall of combustible construction shall be provided with a noncombustible lining or backing.
9.33.7.2.Surface Temperature permalink →
(1) The exposed surface temperature of a steam or hot water radiator shall not exceed 70°C unless precautions are taken
to prevent human contact.
9.33.8.Piping for Heating and Cooling Systems
9.33.8.1.Piping Materials and Installation permalink →
(1) Piping shall be made from materials designed to withstand the effects of temperatures and pressures that may occur
in the system. (See Articles 3.1.5.19., 3.1.9.1. and 9.10.9.7., and Sentence 9.10.9.9.(3) for fire safety requirements.)
(2) Every pipe used in a heating or air-conditioning system shall be installed to allow for expansion and contraction due
to temperature changes.
(3) Supports and anchors for piping in a heating or air-conditioning system shall be designed and installed to ensure that
undue stress is not placed on the supporting structure.
9.33.8.2.Insulation and Coverings permalink →
(1) Insulation and coverings on pipes shall be composed of material suitable for the operating temperature of the system
to withstand deterioration from softening, melting, mildew and mould.
(2) Insulation and coverings on pipes in which the temperature of the fluid exceeds 120°C
(a) shall be made of noncombustible material, or
(b) shall not flame, glow, smoulder or smoke when tested in accordance with ASTM C411, “Standard Specification for
Hot-Surface Performance of High-Temperature Thermal Insulation,” at the maximum temperature to which such
insulation or covering is to be exposed in service.
(3) Except as provided in Sentence (6), where combustible insulation is used on piping in a horizontal or vertical service
space, the insulation and coverings on such pipes shall have a flame-spread rating throughout the material of not more
than
(a) 25 in buildings of noncombustible construction, and
(b) 75 in buildings of combustible construction.
(4) Except as provided in Sentence (6), insulation and coverings on piping located in rooms and spaces other than the
service spaces described in Sentence (3) shall have a flame-spread rating not more than that required for the interior
finish for the ceiling of the room or space.
(5) Pipes that are exposed to human contact shall be insulated so that the exposed surface does not exceed 52°C. (See
Note A-6.5.1.1.(3))
(6) No flame-spread rating or smoke developed classification limitations are required where combustible insulation and
coverings are used on piping when such piping is
(a) located within a concealed space in a wall,
(b) located in a floor slab, or
(c) enclosed in a noncombustible raceway or conduit.
9.33.8.3.Clearances permalink →
(1) Clearances between combustible material and bare pipes carrying steam or hot water shall conform to Table
9.33.8.3.
Table 9.33.8.3.
Clearance Between Steam or Hot Water Pipes and Combustible Material
Forming Part of Sentence 9.33.8.3.(1)
Steam or Water Temperature (T), °C Minimum Clearance, mm
T ≤ 95 no clearance required
95 < T ≤ 120 15
T > 120 25
This provision includes a table — formatting is preserved from the source; refer to the official code for the authoritative layout.
9.33.8.4.Protection permalink →
(1) Where a pipe carrying steam or hot water at a temperature above 120°C passes through a combustible floor, ceiling
or wall, the construction shall be protected by a sleeve of metal or other noncombustible material not less than 50 mm
larger in diameter than the pipe.
(2) Unprotected steam or hot water pipes that pass through a storage space shall be covered with not less than 25 mm
thickness of noncombustible insulation to prevent direct contact with the material stored.
9.33.9.Refrigerating Systems and Equipment for Air-Conditioning
9.33.9.1.Cooling Units permalink →
(1) Where a cooling unit is combined with a fuel-fired furnace in the same duct system, the cooling unit shall be
installed
(a) in parallel with the heating furnace,
(b) upstream of the furnace, provided the furnace is designed for such application, or
(c) downstream of the furnace, provided the cooling unit is designed to prevent excessive temperature or pressure in the
refrigeration system.
9.33.10.Chimneys and Venting Equipment
9.33.10.1.Requirement for Venting permalink →
(1) Except as provided in Articles 9.33.10.2. and 9.33.10.3., the products of combustion from oil-, gas- and solid-fuel-
burning appliances, including stoves, cooktops, ovens and space heaters, shall be vented in conformance with the
applicable appliance installation standard listed in Sentences 9.33.5.2.(1) and 9.33.5.3.(1).
9.33.10.2.Factory-Built Chimneys permalink →
(1) Factory-built chimneys serving solid-fuel-burning appliances, and their installation, shall comply with Sentence
9.21.1.3.(1). (See Note A-9.33.10.2.(1))
9.33.10.3.Masonry or Concrete Chimneys permalink →
(1) Masonry or concrete chimneys shall conform to Section 9.21.
Understand any provision in seconds
BUILDAiD Assist explains any article of the building code in plain English — with exact citations, exceptions and related requirements.
Code text is reproduced for reference from the Ontario Building Code (O. Reg. 163/24, 2024 Building Code Compendium). This page is provided for general information and is not an official copy. Always verify requirements against the official Ontario Building Code and confirm with your local building department.