Part 9 ventilation (9.32): BCIN HVAC

Last updated October 22, 2026

Values this chapter turns on

minimum supplemental kitchen exhaust fan: 50 L/s; minimum supplemental kitchen exhaust fan
minimum supplemental bathroom exhaust fan: 25 L/s; minimum supplemental bathroom exhaust fan
max dwelling unit size for the 9.32.3. method: 5 bedrooms; max dwelling unit size for the 9.32.3. method
outdoor air duct upstream of the furnace, along duct: 3 m; outdoor air duct upstream of the furnace, along duct

Section 9.32. is the heart of this exam. It sets two kinds of ventilation for every residential occupancy: non-heating-season ventilation (windows or a fan) and heating-season mechanical ventilation (a principal ventilation fan with an outdoor air supply, supplemental exhaust and protection against depressurization). Most numbers are in tables, so learn how to read them quickly.

General and non-heating-season ventilation

Section 9.32. applies to rooms and spaces in residential occupancies; other occupancies go to Part 6 OBC Div. B 9.32.1.1.. A storage garage for up to 4 vehicles serving a residence may be treated as part of the residential occupancy.

Every residential occupancy needs OBC Div. B 9.32.1.2.:

non-heating-season ventilation (Subsection 9.32.2.), and
where there is electrical power and a heating system, heating-season ventilation. A self-contained system serving one dwelling unit follows Subsection 9.32.3.

In a house with a secondary suite, heating-season ventilation is not needed for exits, public corridors and ancillary spaces outside the units, but ancillary spaces with exhaust devices still need make-up air.

Dryer exhaust discharges directly outdoors, in its own duct, cleanable, of smooth corrosion-resistant material OBC Div. B 9.32.1.3..

Natural ventilation areas come from the natural ventilation table OBC Div. B Table 9.32.2.2.. Inside a dwelling unit: 0.09 m² for a bathroom or water-closet room, 0.28 m² per finished room (or combination of rooms), and 0.2% of floor area for an unfinished basement. A living or dining room may ventilate through a vestibule, and non-window openings need weather and insect protection OBC Div. B 9.32.2.2..

Mechanical alternative. A room without natural ventilation that is mechanically cooled needs a fan sized to the air change table, or a system meeting 9.32.3. OBC Div. B 9.32.2.3.. The master bedroom is 10 L/s and most other rooms 5 L/s OBC Div. B Table 9.32.2.3.. Basement areas used for other purposes get 10 L/s if they exceed 2/3 of the basement floor area, otherwise 5 L/s. A room that is not mechanically cooled needs one air change per hour.

Practice this topic

Heating-season mechanical ventilation: capacity and fans

A system complying with 9.32.3. may be used for dwelling units with 5 or fewer bedrooms; otherwise use CAN/CSA-F326-M good practice or Part 6 OBC Div. B 9.32.3.1.. It must include a principal ventilation system, supplemental exhaust fans and depressurization protection. CSA F326 itself is an external standard; the exam asks when it is the required route, not what it says.

Principal ventilation fan capacity is read from the bedroom table OBC Div. B Table 9.32.3.3.. Our summary of the minimum and maximum normal operating exhaust capacities:

Bedrooms	Minimum (L/s)	Maximum (L/s)
1	16	24
3	22	32
5	30	45

(Check the code table for 2 and 4 bedrooms.) Above 5 bedrooms, 9.32.3.1.(1)(a) applies.

Principal fan rules OBC Div. B 9.32.3.3.:

May be a single fan, the exhaust side of an HRV, or a group of fans controlled together.
Approved by the manufacturer for continuous operation.
Manual switch in the living area marked "ventilation fan"; a dehumidistat override is allowed if it is in the living area and marked the same way; the manual switch always overrides the automatic control.
An exhaust intake connected to the furnace return is at least 1 m upstream of the outdoor air duct connection.
Intakes in kitchens, bathrooms and water-closet rooms are in the ceiling or at least 2 m up the wall.

Outdoor air through a forced-air furnace OBC Div. B 9.32.3.4.. The outdoor air duct connects to the return plenum at least 3 m upstream of the furnace (measured along the duct) or through a mixing device, has a flow-regulating damper, and is set so outdoor airflow is within plus or minus 10% of the principal fan's actual exhaust capacity (measured to plus or minus 15% accuracy). Starting the principal fan must start the furnace circulation fan. If the outdoor air would drop the mixed air below 15°C (or the furnace maker's minimum, whichever is less) at the January 2.5% temperature, temper it or use another method. The outdoor airflow limits are in the mixed-air table OBC Div. B Table 9.32.3.4., and linear interpolation is allowed.

Outdoor air without a forced-air furnace OBC Div. B 9.32.3.5.: an outdoor air supply fan within plus or minus 10% of the exhaust fan, tempered to at least 12°C unless supplied by an HRV, ducted to each bedroom and each storey without a bedroom, with supply outlets in the ceiling or at least 2 m up a wall.

Exhaust-only systems are allowed only with no solid-fuel appliance, no fireplace other than direct-vented, and no other fuel-fired space or water heater other than direct-vented or mechanically vented types, plus a forced-air circulation fan rated at least 5 times the principal fan's capacity OBC Div. B 9.32.3.6..

Fan ratings OBC Div. B 9.32.3.10.. Rate capacity at the static pressure in the fan rating table: 100 Pa for fans ducted on both sides, 62 Pa for an exhaust-only principal fan ducted on one side, 25 Pa for others OBC Div. B Table 9.32.3.10.-A. Fans within 1 m of duct of a finished room must meet the sone limits OBC Div. B Table 9.32.3.10.-B. An HRV needs a low-temperature ventilation reduction factor of at least 50%.

Practice this topic

Supplemental exhaust, makeup air and depressurization

Supplemental exhaust OBC Div. B 9.32.3.7.:

Room	Fan	Exemption
Kitchen	At least 50 L/s	Only principal intake is in the kitchen; or principal fan has a kitchen high-speed switch at 2.5 times the table minimum, labelled "kitchen exhaust"
Bathroom or water-closet room	At least 25 L/s	A principal fan intake is in that room

Each supplemental fan has a manual switch in the room it serves.

Depressurization protection OBC Div. B 9.32.3.8. applies where a dwelling unit has a fuel-fired space or water heater that is not direct-vented or mechanically vented. Any exhaust device other than the principal fan (running within the table maximum) needs a make-up air fan delivering at least the device's exhaust capacity and not more than that plus 10%, interlocked with the device, and either delivered to an unoccupied area or tempered to at least 12°C. Exemptions: solid-fuel appliances where all other fuel-fired appliances are direct or mechanically vented; a CAN/CGSB-51.71 depressurization test showing limits are met; and radon subfloor depressurization fans.

Ducts, HRVs and terminations. Exhaust ducts never discharge into attics or other enclosed spaces; insulate exhaust ducts in unheated space and untempered outdoor air ducts in heated space to at least RSI 0.5 OBC Div. B 9.32.3.11.. Intakes within 3 m horizontally of a cooktop need grease filters. HRVs are not connected in parallel to a common duct, and need a condensate drain of at least 1/2 inch with a trap OBC Div. B 9.32.3.12.. Intakes sit at least 450 mm above grade (or expected snow), at least 1,800 mm from contaminant sources and moist exhaust outlets; exhaust outlets at least 100 mm above grade; backdraft dampers except on HRV outlets OBC Div. B 9.32.3.13..

Practice this topic

Carbon monoxide alarms

Part 9 CO alarm rules match Part 6 (see Chapter 5) with additions for houses with a secondary suite OBC Div. B 9.32.3.9. OBC Div. B 9.32.3.9A. OBC Div. B 9.32.3.9B. OBC Div. B 9.32.3.9C.. Alarms go adjacent to each sleeping room and on each storey without one, plus inside any sleeping room that contains or adjoins a fuel-burning appliance, flue or garage (or adjoins an attic or crawl space the garage also adjoins). In a house with a secondary suite, all CO alarms in the house and common spaces are interconnected.

Practice this topic

Common traps

Using 9.32.3. for a 6-bedroom dwelling unit. It stops at 5.
Forgetting the "plus 10%" ceiling on make-up air: oversizing is also non-compliant.
Measuring the 3 m outdoor air duct distance in a straight line rather than along the duct.

Chapter review

Chapter at a glance

One line per section: the idea to carry into the exam. Then the answers that most often catch candidates out.

Chapter at a glance: the key idea in each section
Section	Key idea
General and non-heating-season ventilation	Section 9.32. applies to rooms and spaces in residential occupancies; other occupancies go to Part 6. A storage garage for up to 4 vehicles serving a residence may be treated as…
Heating-season mechanical ventilation: capacity and fans	A system complying with 9.32.3. may be used for dwelling units with 5 or fewer bedrooms; otherwise use CAN/CSA-F326-M good practice or Part 6. It must include a principal…
Supplemental exhaust, makeup air and depressurization	Each supplemental fan has a manual switch in the room it serves.
Carbon monoxide alarms	Part 9 CO alarm rules match Part 6 (see Chapter 5) with additions for houses with a secondary suite.

General and non-heating-season ventilation
Section 9.32. applies to rooms and spaces in residential occupancies; other occupancies go to Part 6. A storage garage for up to 4 vehicles serving a residence may be treated as…
Heating-season mechanical ventilation: capacity and fans
A system complying with 9.32.3. may be used for dwelling units with 5 or fewer bedrooms; otherwise use CAN/CSA-F326-M good practice or Part 6. It must include a principal…
Supplemental exhaust, makeup air and depressurization
Each supplemental fan has a manual switch in the room it serves.
Carbon monoxide alarms
Part 9 CO alarm rules match Part 6 (see Chapter 5) with additions for houses with a secondary suite.

Usual exam traps

Using 9.32.3. for a 6-bedroom dwelling unit. It stops at 5.
Forgetting the "plus 10%" ceiling on make-up air: oversizing is also non-compliant.
Measuring the 3 m outdoor air duct distance in a straight line rather than along the duct.

Practice this chapter

Questions on Part 9 ventilation (9.32), in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.

Practice this chapter HVAC - House calculations

Code cited in this chapter

Based on the official 2024 Building Code Compendium on ontario.ca.

OBC Div. B 9.32.1.1. Application
(1)This Section applies to the ventilation of rooms and spaces in residential occupancies.
(2)Ventilation of all other occupancies shall comply with Part 6.
(3)A storage garage for up to 4 motor vehicles that serves a residential occupancy may be considered to be part of that occupancy.
Open OBC Div. B 9.32.1.1. in the code viewer
OBC Div. B 9.32.1.2. Required Ventilation
(1)Every residential occupancy shall incorporate
(a)provisions for non-heating-season ventilation in accordance with Subsection 9.32.2., and
(b)except as required by Sentences (2) and (3), if supplied with electrical power and a heating system, provisions for heating-season ventilation in accordance with Part 6.
(2)A self-contained heating-season ventilation system serving a single dwelling unit shall comply with Subsection 9.32.3. (See Note A-9.32.1.2.(2))
(3)In houses that contain a secondary suite, heating-season ventilation need not be provided for
(a)exits,
(b)public corridors, and
(c)ancillary spaces that are not within a dwelling unit, except as provided in Sentence (4).
(See Note A-9.32.1.2.(2))
(4)Where ancillary spaces described in Clause (3)(c) contain exhaust devices, these spaces shall be provided with make-up air in accordance with Article 9.32.3.8.
Open OBC Div. B 9.32.1.2. in the code viewer
OBC Div. B 9.32.1.3. Venting of Laundry-Drying Equipment
(1)Exhaust ducts or vents connected to laundry-drying equipment shall discharge directly to the outdoors.
(2)Exhaust ducts connected to laundry-drying equipment shall be
(a)independent of other exhaust ducts,
(b)accessible for cleaning, and
(c)constructed of a smooth corrosion-resistant material.
(3)Where collective venting of multiple installations of laundry-drying equipment is used, the ventilation system shall
(a)be connected to a common exhaust duct that is vented by one central exhaust fan, and incorporates one central lint trap,
(b)include an interlock to activate the central exhaust fan when laundry-drying equipment is in use, and
(c)where required by Article 9.32.3.8., be provided with make-up air.
Open OBC Div. B 9.32.1.3. in the code viewer
OBC Div. B Table 9.32.2.2. Natural Ventilation - Forming Part of Sentence 9.32.2.2.(1)
Table 9.32.2.2. Natural Ventilation - Forming Part of Sentence 9.32.2.2.(1) Forming Part of Sentence 9.32.2.2.(1) Application | Location | Minimum Unobstructed Area Within a dwelling unit | Bathrooms or water-closet rooms | 0.09 m² Within a dwelling unit | Unfinished basement space | 0.2% of the floor area Within a dwelling unit | Dining rooms, living rooms, bedrooms, kitchens, combined rooms, dens, recreation rooms and all other finished rooms | 0.28 m² per room or combination of rooms Other than within a dwelling unit | Bathrooms or water-closet rooms | 0.09 m² per water closet Other than within a dwelling unit | Sleeping areas | 0.14 m² per occupant Other than within a dwelling unit | Laundry rooms, kitchens, recreation rooms | 4% of the floor area Other than within a dwelling unit | Corridors, storage rooms and other similar public rooms or spaces | 2% of the floor area Other than within a dwelling unit | Unfinished basement space not used on a shared basis | 0.2% of the floor area
Open OBC Div. B Table 9.32.2.2. in the code viewer
OBC Div. B 9.32.2.2. Non-Heating-Season Natural Ventilation
(1)The unobstructed openable ventilation area to the outdoors for rooms and spaces in residential buildings ventilated by natural means shall conform to Table 9.32.2.2.
(2)Where a vestibule opens directly off a living or dining room within a dwelling unit, ventilation to the outdoors for such rooms may be through the vestibule.
(3)Openings for natural ventilation other than windows shall provide protection from the weather and insects.
(4)Screening shall be of corrosion-resistant material.
Open OBC Div. B 9.32.2.2. in the code viewer
OBC Div. B 9.32.2.3. Non-Heating-Season Mechanical Ventilation
(1)Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is mechanically cooled, its non-heating-season mechanical ventilation system shall
(a)have the capacity to exhaust air from inside the room or space, or to introduce outdoor air into that room or space, at a rate conforming with Table 9.32.2.3., or
(b)comply with Subsection 9.32.3.
(2)In applying Clause (1)(a),
(a)at least one bedroom in each dwelling unit shall be designated as the master bedroom,
(b)air change rates for any combined living/dining or family/dining space shall be determined as if the spaces were individual rooms,
(c)where a basement incorporates rooms of the types designated in Table 9.32.2.3., the assigned air change rate for each room shall be as specified for those types of rooms,
(d)basement areas used for other purposes that exceed 2/3 of the total basement floor area shall be assigned an air change rate of 10 L/s,
(e)basement areas used for other purposes that are 2/3 of the total basement floor area or less shall be assigned an air change rate of 5 L/s, and
(f)other habitable rooms, other than spaces intended solely for access, egress, storage, or service equipment, shall be assigned an air change rate of 5 L/s.
(3)Where a habitable room or space is not provided with natural ventilation as described in Article 9.32.2.2. and is not mechanically cooled, the non-heating-season mechanical ventilation system shall have the capacity to exhaust indoor air from the room or space or to introduce outdoor air to that room or space at a rate of one air change per hour.
(4)A non-heating-season mechanical ventilation system shall be designed and installed in conformance with good practice such as that described in the ASHRAE Handbooks and Standards, the HRAI Digest, the Hydronics Institute Manuals and the SMACNA Manuals.
Open OBC Div. B 9.32.2.3. in the code viewer
OBC Div. B Table 9.32.2.3. Air Change Rate — Forming Part of Clause 9.32.2.3.(1)(a)
Table 9.32.2.3. Air Change Rate — Forming Part of Clause 9.32.2.3.(1)(a) Forming Part of Clause 9.32.2.3.(1)(a) Room or Space | Rate, L/s Master bedroom | 10 Other bedrooms | 5 Living room | 5 Dining room | 5 Family room | 5 Recreation room | 5 Basement | 10 Kitchen | 5 Bathroom or water closet room | 5 Laundry room | 5 Utility room | 5 Other habitable rooms | 5
Open OBC Div. B Table 9.32.2.3. in the code viewer
OBC Div. B 9.32.3.1. Required Ventilation
(1)The heating-season ventilation required by Clause 9.32.1.2.(1)(b) shall be provided by a mechanical ventilation system complying with
(a)good practice such as that described in CAN/CSA-F326-M, "Residential Mechanical Ventilation Systems,"
(b)for dwelling units with 5 or fewer bedrooms, the balance of this Subsection, or
(c)Part 6.
(2)Mechanical ventilation systems complying with the balance of this Subsection shall incorporate at least the following components:
(a)a principal ventilation system complying with Article 9.32.3.3.,
(b)supplemental exhaust fans complying with Article 9.32.3.7., and
(c)protection against depressurization in accordance with Article 9.32.3.8.
Open OBC Div. B 9.32.3.1. in the code viewer

Show all 26 articles

OBC Div. B Table 9.32.3.3. Normal Operating Exhaust Capacity of Principal Ventilation Fan - Forming Part of Sentence 9.32.3.3.(2)
Table 9.32.3.3. Normal Operating Exhaust Capacity of Principal Ventilation Fan - Forming Part of Sentence 9.32.3.3.(2) Forming Part of Sentence 9.32.3.3.(2) Number of Bedrooms in Dwelling Unit | Minimum Normal Operating Exhaust Capacity of Principal Ventilation Fan, L/s | Maximum Normal Operating Exhaust Capacity of Principal Ventilation Fan, L/s 1 | 16 | 24 2 | 18 | 28 3 | 22 | 32 4 | 26 | 38 5 | 30 | 45 More than 5 | System must comply with Clause 9.32.3.1.(1)(a) | System must comply with Clause 9.32.3.1.(1)(a)
Open OBC Div. B Table 9.32.3.3. in the code viewer
OBC Div. B 9.32.3.3. Principal Ventilation System
(1)The principal ventilation system shall incorporate the following components:
(a)a principal ventilation fan complying with this Article, and
(b)except as permitted by Article 9.32.3.6., provision for the introduction of outdoor air to the dwelling unit, in conformance with Article 9.32.3.4. or 9.32.3.5.
(2)The principal ventilation fan shall be capable of operating at an exhaust capacity complying with Table 9.32.3.3., referred to hereinafter as the "normal operating exhaust capacity." (See Note A-9.32.3.3.(2))
(3)The requirement for a principal ventilation fan may be satisfied by a single fan, by the exhaust side of a heat recovery ventilator, or by a group of fans, provided all fans in the group are controlled simultaneously by a controller complying with Sentences (5) to (7). (See Note A-9.32.3.3.(3))
(4)The components of the principal ventilation system shall be approved by their manufacturer for continuous operation.
(5)The principal ventilation fan shall be controlled by a manual switch located within the living area of the dwelling unit and clearly marked ventilation fan. (See Note A-9.32.3.3.(5))
(6)If all controls serving the principal ventilation fan are in the "off" position, the principal ventilation system shall not operate.
(7)The requirement for a manual switch stated in Sentence (5) can be satisfied by a manual override incorporated in a dehumidistat or other automatic control, provided
(a)the automatic control is located within the living area of the dwelling unit, and
(b)the manual override is clearly marked ventilation fan.
(8)Where the principal ventilation fan is controlled by a dehumidistat or other automatic control in addition to the manual switch required by Sentence (5), the manual switch shall be capable of activating the fan regardless of the setting of the automatic control.
(9)Where an exhaust air intake for the principal ventilation fan is connected directly to the return side of the duct system of a forced air heating system or other forced air distribution system, it shall be connected, where applicable, not less than 1 m upstream from the connection of the outdoor air supply duct required by Sentence 9.32.3.4.(5).
(10)Exhaust air intakes for principal ventilation fans located in kitchens, bathrooms and water-closet rooms shall be located in the ceiling or on the wall not less than 2 m above the floor. (See Note A-9.32.3.3.(10))
Open OBC Div. B 9.32.3.3. in the code viewer
OBC Div. B 9.32.3.4. Ventilation Systems Used in Conjunction with Forced Air Heating Systems
(1)Where outdoor air is to be introduced to the dwelling unit through a forced air heating system, the provision of outdoor air shall comply with this Article.
(2)Where the actual normal operating exhaust capacity of the fan installed to satisfy the requirement for a principal ventilation fan exceeds the maximum outdoor airflow permitted by Table 9.32.3.4. for a mixed air temperature of 15°C or exceeds the minimum acceptable return air temperature specified by the manufacturer of the furnace, whichever is less, then either
(a)the system shall incorporate a means for tempering outdoor air introduced to the heating system ducts so that a mixed air temperature of 15°C or the minimum acceptable return air temperature specified by the manufacturer of the furnace, whichever is less, is achieved when the outdoor air is at the January 2.5% temperature and the indoor air temperature is 22°C, or
(b)this Article shall be considered to be no longer applicable and the mechanical ventilation system shall comply with either Clause 9.32.3.1.(1)(a) or with Article 9.32.3.5.
(3)For the purposes of Table 9.32.3.4., the furnace airflow shall be determined
(a)by operating the forced air heating system's circulation fan at the rate chosen to satisfy Clause (9)(a) when measuring the return airflow in the furnace return air plenum immediately upstream of the connection of the outdoor air supply duct required by Sentence (5) and then adding this return airflow measurement to the actual normal operating exhaust capacity of the fan installed to satisfy the requirement for a principal ventilation fan, or
(b)by using the manufacturer's rated flow for the furnace for 150 Pa static pressure and the wiring configuration necessary to achieve the flow specified in Clause (9)(a).
(4)Linear interpolation is permitted in using Table 9.32.3.4.
(5)An outdoor air supply duct shall be installed between the outdoors and the furnace return air plenum and shall be connected
(a)not less than 3 m upstream of the plenum connection to the furnace, as measured along the length of the duct, or
(b)through an acceptable mixing device installed in the return air plenum.
(6)The outdoor air supply duct required by Sentence (5) shall incorporate a flow-regulating damper.
(7)Where the outdoor air supply duct required by Sentence (5) is not connected to an outdoor air supply fan, it shall be connected downstream of all return branch connections.
(8)Where the outdoor air supply duct required by Sentence (5) is connected to an auxiliary outdoor air supply fan, the auxiliary outdoor air supply fan shall be
(a)approved by the manufacturer for the handling of untempered outdoor air if it will be handling untempered outdoor air,
(b)approved by the manufacturer for continuous operation, and
(c)designed to provide an outdoor air supply flow within ± 10% of the actual normal operating exhaust capacity of the exhaust fan installed to satisfy the requirement for a principal ventilation fan.
(9)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 forced air heating system's circulation fan to provide an airflow not greater than the space-heating airflow,
(b)where applicable, activation of the principal ventilation fan automatically activates the auxiliary outdoor air supply fan described in Sentence (8), and
(c)the auxiliary outdoor air supply fan does not operate when the principal ventilation fan is not operating.
(10)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 (6) 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.
(11)The airflow measurements required by Sentences (3) and (10) shall be done using a method accurate to within ± 15% of the flow rate being measured.
(12)All connections between the ventilation system and the heating system shall be in accordance with Articles 9.33.4.1. and 9.33.5.2.
Open OBC Div. B 9.32.3.4. in the code viewer
OBC Div. B Table 9.32.3.4. Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of 0°C
Table 9.32.3.4. — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of 0°C Forming Part of Sentence 9.32.3.4.(2) Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 32 L/s | 55 L/s | 77 L/s 200 | 64 L/s | 109 L/s | 155 L/s 300 | N/A | N/A | N/A 400 | N/A | N/A | N/A 500 | N/A | N/A | N/A Table 9.32.3.4. (continued) — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of -10°C Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 22 L/s | 38 L/s | 53 L/s 200 | 44 L/s | 75 L/s | 106 L/s 300 | 66 L/s | 113 L/s | 159 L/s 400 | N/A | N/A | N/A 500 | N/A | N/A | N/A Table 9.32.3.4. (continued) — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of -20°C Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 17 L/s | 29 L/s | 40 L/s 200 | 33 L/s | 57 L/s | 81 L/s 300 | 50 L/s | 86 L/s | 121 L/s 400 | N/A | N/A | N/A 500 | N/A | N/A | N/A Table 9.32.3.4. (continued) — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of -30°C Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 13 L/s | 23 L/s | 33 L/s 200 | 27 L/s | 46 L/s | 65 L/s 300 | 40 L/s | 69 L/s | 98 L/s 400 | 54 L/s | 92 L/s | 131 L/s 500 | N/A | N/A | N/A Table 9.32.3.4. (continued) — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of -40°C Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 11 L/s | 19 L/s | 27 L/s 200 | 23 L/s | 39 L/s | 55 L/s 300 | 34 L/s | 58 L/s | 82 L/s 400 | 45 L/s | 77 L/s | 110 L/s 500 | N/A | N/A | N/A Table 9.32.3.4. (continued) — Maximum Outdoor Airflow for Indicated Mixed Temperature for January 2.5% Temperature as per Supplementary Standard SB-1 of -50°C Furnace Airflow, L/s | Minimum Mixed Air Temperature, 15°C | Minimum Mixed Air Temperature, 10°C | Minimum Mixed Air Temperature, 5°C 0 | 0 L/s | 0 L/s | 0 L/s 100 | 10 L/s | 17 L/s | 24 L/s 200 | 19 L/s | 33 L/s | 47 L/s 300 | 29 L/s | 50 L/s | 71 L/s 400 | 39 L/s | 67 L/s | 94 L/s 500 | 49 L/s | 83 L/s | 118 L/s
Open OBC Div. B Table 9.32.3.4. in the code viewer
OBC Div. B 9.32.3.5. Ventilation Systems Not Used in Conjunction with Forced Air Heating Systems
(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.
Open OBC Div. B 9.32.3.5. in the code viewer
OBC Div. B 9.32.3.6. Exhaust-Only Ventilation Systems
(1)A ventilation system with no provision for the introduction of outdoor air to the dwelling unit may only be used where the dwelling unit
(a)contains no solid-fuel-burning appliance, no fireplace of other than direct-vented type, and no other fuel-fired space- or water-heating appliance of other than direct-vented or mechanically vented types, and
(b)has a forced air distribution system with a circulation fan with a rated capacity equal to at least 5 times the actual normal operating exhaust capacity of the fan installed to satisfy the requirement for a principal ventilation fan, a supply side that complies with Sentences 9.32.3.5.(10) to (12), and a return side that complies with Articles 9.33.6.12. and 9.33.6.13.
(2)Except as provided in Sentence (3), where an exhaust-only system is installed, the principal ventilation fan control required by Sentence 9.32.3.3.(5) shall be wired in such a way that, where applicable, activation of the principal ventilation fan automatically activates the circulation fan of the forced air distribution system required by Clause (1)(b) at its rated capacity.
(3)Interlocking the forced air distribution system's circulation fan with the principal ventilation fan as required by Sentence (2) is not required where the forced air distribution system is equipped with a control that automatically activates the circulation fan at user-selected intervals.
Open OBC Div. B 9.32.3.6. in the code viewer
OBC Div. B 9.32.3.10. Fans
(1)Except as provided in Sentence (4), capacity ratings for required fans shall be determined in accordance with
(a)CAN/CSA-C260-M, "Rating the Performance of Residential Mechanical Ventilating Equipment," or
(b)HVI Publication 916, "Airflow Test Procedure."
(2)Sound ratings for fans shall be determined in accordance with
(a)CAN/CSA-C260-M, "Rating the Performance of Residential Mechanical Ventilating Equipment," or
(b)HVI Publication 915, "Loudness Testing and Rating Procedure."
(3)Capacity ratings for fans shall be measured at the external static pressure differentials shown in Table 9.32.3.10.-A.
(4)Fans in heat recovery ventilators used to provide one or more required fans shall have their airflow at normal temperature rated in accordance with CAN/CSA-C439, "Standard laboratory methods of test for rating the performance of heat/energy-recovery ventilators."
(5)Where a heat recovery ventilator is used to provide one or more required fans, it shall have a low-temperature ventilation reduction factor of not less than 50% when tested in accordance with CAN/CSA-C439, "Standard laboratory methods of test for rating the performance of heat/energy-recovery ventilators," at an outdoor temperature at least as low as the outdoor design temperature for the location where the ventilation system is to be installed, but the outdoor design temperature need not be lower than -25°C.
(6)Fans, including make-up air supply fans, installed to satisfy Articles 9.32.3.3. to 9.32.3.8. with less than 1 m of duct between themselves and the visible interior surfaces of rooms other than unfinished basements, furnace rooms, utility rooms and attics, shall have a sound rating complying with Table 9.32.3.10.-B when operating at the required flow rate.
(7)Mechanical ventilation devices shall conform to CSA C22.2 No. 113, "Fans and Ventilators."
Open OBC Div. B 9.32.3.10. in the code viewer
OBC Div. B Table 9.32.3.10-A. Minimum External Static Pressure Differential for Rating of Fans - Forming Part of Sentence 9.32.3.10.(3)
Table 9.32.3.10.-A Minimum External Static Pressure Differential for Rating of Fans - Forming Part of Sentence 9.32.3.10.(3) Forming Part of Sentence 9.32.3.10.(3) Fan Configuration or Application | Minimum External Static Pressure Differential to be Used in Determining Rated Capacity Fans installed with ducts connected on both sides, any application | 100 Pa (0.4 inch water column) Fans installed with ducts on one side only, used as the principal ventilation fan in exhaust-only systems permitted by Article 9.32.3.6. | 62 Pa (0.25 inch water column) Other required fans | 25 Pa (0.1 inch water column)
Open OBC Div. B Table 9.32.3.10-A. in the code viewer
OBC Div. B Table 9.32.3.10-B. Maximum Sound Rating for Fans - Forming Part of Sentence 9.32.3.10.(6)
Table 9.32.3.10.-B Maximum Sound Rating for Fans - Forming Part of Sentence 9.32.3.10.(6) Forming Part of Sentence 9.32.3.10.(6) Fan Application | Maximum Sound Rating according to CAN/-C260-M, sones | Maximum Sound Rating according to HVI 915 Principal exhaust fan | 2.0 | 2.5 Supplemental exhaust fans installed in bathrooms and their make-up air fans | 2.5 | 3.5 Supplemental exhaust fans installed in kitchens and their make-up air fans | no rating required | no rating required
Open OBC Div. B Table 9.32.3.10-B. in the code viewer
OBC Div. B 9.32.3.7. Supplemental Exhaust
(1)Except as provided in Sentences (2) and (3), a supplemental exhaust fan with a rated capacity not less than 50 L/s shall be installed in each kitchen.
(2)A supplemental exhaust fan is not required in a kitchen where the only exhaust air intake for the principal ventilation fan is located in that kitchen.
(3)A supplemental exhaust fan is not required in a kitchen where the principal ventilation fan draws from that kitchen and other rooms, provided
(a)the principal ventilation fan can be switched to a high exhaust rate equal to not less than 2.5 times the minimum normal operating exhaust capacity specified in Table 9.32.3.3., and
(b)the high exhaust rate of the principal ventilation fan, as described in Clause (a), is activated by a manual switch in the kitchen labeled "kitchen exhaust."
(4)Where an exhaust air intake for the principal ventilation fan is not located in a bathroom or water-closet room, a supplemental exhaust fan with a rated capacity not less than 25 L/s shall be installed in that bathroom or water-closet room.
(5)Where the intake for a supplemental exhaust fan other than a cooking appliance exhaust fan serving a cooktop is installed in a kitchen, it shall be installed in the ceiling or on the wall at not less than 2 m above the floor.
(6)A supplemental exhaust fan required by this Article shall be controlled by a manual switch located in the room served by the fan.
(7)Where a kitchen or bathroom is exempted from the requirement to install a supplemental exhaust fan by virtue of Sentence (2) or (3), the principal ventilation fan shall be controlled by a manual switch located in the kitchen or bathroom and wired in parallel with the manual switch required by Sentence 9.32.3.3.(5).
(8)Where a supplemental exhaust fan required by this Article is controlled by a dehumidistat or other automatic control in addition to the manual switch required by Sentence (6), the manual switch shall be capable of activating the fan regardless of the setting of the automatic control.
Open OBC Div. B 9.32.3.7. in the code viewer
OBC Div. B 9.32.3.8. Protection Against Depressurization
(1)This Article applies to
(a)dwelling units that contain a fuel-fired space-heating appliance or fuel-fired water-heating appliance of other than direct-vented or mechanically vented types, and
(b)ancillary spaces that contain an exhaust device, where the space is not within a dwelling unit in a house with a secondary suite and where the house with a secondary suite contains a fuel-fired space-heating appliance or fuel-fired water-heating appliance of other than direct-vented or mechanically vented types.
(2)Except as provided in Sentences (6) to (8), any mechanical air exhausting device, other than the principal ventilation fan operating at a rate not greater than the maximum permitted by Table 9.32.3.3., shall be provided with outdoor make-up air supplied by a fan rated to deliver outdoor air to the dwelling unit at a rate
(a)not less than the exhaust capacity of the device, and
(b)not greater than that exhaust capacity plus 10%.
(3)An outdoor make-up air supply fan required by Sentence (2) shall be wired so that it is activated whenever the device for which it supplies outdoor make-up air is activated.
(4)The outdoor make-up air required by Sentence (2) shall be
(a)introduced to a normally unoccupied area in the dwelling unit, or
(b)tempered to at least 12°C before being introduced to occupied areas or to a supply duct system.
(5)If the outdoor make-up air required by Sentence (2) is not tempered upstream of the supply fan, the supply fan required by Sentence (2) shall be approved by the manufacturer for the handling of untempered outdoor air.
(6)The provision of make-up air as described in Sentence (2) is not required in a dwelling unit with solid-fuel-burning appliances, where all other fuel-fired appliances are direct-vented or mechanically vented.
(7)The provision of make-up air as described in Sentence (2) is not required if it can be shown using the test procedures in CAN/CGSB-51.71, "Depressurization Test," that the maximum depressurization levels to which fuel-fired space- or water-heating appliances and their venting systems will be exposed will not exceed the limits set out in CAN/CGSB-51.71 for the categories of fuel-fired appliances and venting systems installed in the dwelling unit.
(8)The provision of make-up air as described in Sentence (2) is not required for mechanical exhausting devices operating a subfloor depressurization system installed for the purpose of reducing the risk of radon ingress.
Open OBC Div. B 9.32.3.8. in the code viewer
OBC Div. B 9.32.3.11. Ducts
(1)Except as provided in Sentence (6), ventilation ducts and their fittings shall conform to the requirements of Article 9.33.6.2., except that exhaust ducts serving only a bathroom or water-closet room are permitted to be of combustible material, provided they are reasonably airtight and constructed of a material impervious to water.
(2)Exhaust ducts shall not discharge into heated or unheated enclosed spaces.
(3)Where an exhaust duct passes through an unheated space or is not separated from an unheated space by an insulated building assembly, the duct shall be insulated to not less than RSI 0.5.
(4)Where a duct carrying outdoor air that is not tempered and not mixed with indoor air passes through heated space, it shall be
(a)insulated to not less than RSI 0.5, and
(b)provided with a vapour barrier.
(5)All exhaust intakes located within 3 m horizontally of a cooktop shall be equipped with a grease filter at the intake end.
(6)Ductwork for cooking appliance exhaust fans shall
(a)be of noncombustible, corrosion-resistant material,
(b)lead directly to the outdoors with no connections to other exhaust fans or ducts, and
(c)be equipped with a grease filter at the intake end.
(7)All ductwork shall be installed to avoid crushing and shall be permanently supported to prevent sagging.
(8)Joints in all ventilation system ducting shall be sealed with mastic, metal foil duct tape or the manufacturers' specified sealants.
(9)Except where the size of a duct can be determined using Table 9.32.3.11.-A or Table 9.32.3.11.-B, duct sizes shall be determined according to Subsection 9.33.4.
(10)In using Table 9.32.3.11.-A,
(a)when sizing branch ducts, "maximum length of duct" refers to the physical length of the duct from the interior grille served by that branch duct to the exterior hood,
(b)when sizing a trunk duct, "maximum length of duct" refers to the physical length of the duct from the interior grille of the longest branch served by that trunk to the exterior hood,
(c)outdoor air supply ducts shall be sized as trunk ducts,
(d)"maximum airflow in duct" refers to the maximum airflow rate that a given section of duct (branch or trunk) must provide to satisfy the ventilation system design, and
(e)"fan's external static pressure" refers to the external static pressure at which the fan is rated to achieve the maximum airflow rate that the fan is required or intended to provide.
(11)Where flexible duct is used, it may be sized by choosing the next higher diameter in Table 9.32.3.11.-A or by choosing the diameter for a duct twice as long as the actual length.
(12)Where rectangular duct is used in place of round duct, it shall be selected according to Table 9.32.3.11.-B.
Open OBC Div. B 9.32.3.11. in the code viewer
OBC Div. B 9.32.3.12. Heat Recovery Ventilators
(1)This Article shall apply to heat recovery ventilators installed to provide one or more of the fans required by this Subsection.
(2)Two or more heat recovery ventilators shall not be connected in parallel airflow to a common air supply duct, unless specifically permitted by the manufacturer.
(3)Two or more heat recovery ventilators shall not be connected in parallel airflow to a common downstream exhaust duct.
(4)All start-up procedures recommended by the manufacturer, including air balancing and airflow determination, shall be followed.
(5)A means for the free flow of condensate shall be provided in accordance with the manufacturer's recommendations or, in their absence, a condensate drain of at least 1/2 inch nominal pipe size pitched in the direction of flow and complete with a trap or condensate pump of sufficient capacity shall be installed and connected to the dwelling unit's drain, waste and vent system.
(6)The heat recovery ventilator and all condensate lines shall be installed in a space where the ambient temperature will not adversely affect the operation of the system.
Open OBC Div. B 9.32.3.12. in the code viewer
OBC Div. B 9.32.3.13. Outdoor Intake and Exhaust Openings
(1)Intake openings shall be located so as to avoid contamination of the ventilation air from other local sources such as automobile exhaust and exhaust from the building or adjacent buildings.
(2)The distance from the bottom of an air intake opening to finished ground or to any nearer and lower permanent horizontal surface shall be not less than 450 mm or the depth of expected snow accumulation, whichever is greater.
(3)The distance separating air intakes for mechanical ventilation from exhaust outlets that are potential sources of contaminants, such as gas vents or oil fill pipes, shall be not less than 1,800 mm.
(4)Except as provided in Sentences (5) and (6), exhaust outlets that discharge air containing moisture, such as bathroom ventilation and clothes dryer exhaust outlets, shall be located at least 1,800 mm from air intakes and vented soffits.
(5)Where an exhaust outlet referred to in Sentence (4) is located within a soffit, the soffit shall either be unvented, or if vented, the full depth of the soffit shall be blocked for a distance of 1,800 mm on each side of the exhaust outlet.
(6)Where an exhaust outlet referred to in Sentence (4) is located in a side wall less than 1,800 mm from a soffit, a section of the soffit above the exhaust outlet shall be unvented, or if vented, the full depth of the soffit shall be blocked in accordance with the widths stipulated in Table 9.32.3.13.-A, centred over the location of the outlet.
(7)Air intakes shall be clearly labeled as such for identification from locations outside the dwelling unit.
(8)The distance from the bottom of an exhaust outlet to finished ground or to any nearer and lower permanent horizontal surface shall be not less than 100 mm.
(9)Where air intake and exhaust openings are in exposed locations, provision shall be made to protect them from the entry of precipitation by the use of louvres, weather cowls or other suitable protection.
(10)Air intake openings shall incorporate screens or grilles to protect against the entry of animals and insects.
(11)Except for exhaust outlets serving heat recovery ventilators, exhaust outlets shall incorporate backdraft dampers.
(12)An exhaust outlet that does not incorporate a backdraft damper located at the building envelope shall incorporate a screen located at the building envelope to protect against the entry of animals.
(13)Screens, grilles and filters installed in air intake and exhaust openings shall be easily removable for cleaning purposes, without the need for special tools.
(14)Where screens or grilles are installed in air intake and exhaust openings, the net free area of the air intake or exhaust opening shall be equal to or greater than the required cross-sectional area of the duct served or such openings shall comply with Table 9.32.3.13.-B.
(15)Screens and grilles shall be of corrosion-resistant material.
Open OBC Div. B 9.32.3.13. in the code viewer
OBC Div. B 9.32.3.9. Application of Carbon Monoxide Alarms
(1)Article 9.32.3.9A. applies to every building that
(a)contains a supply duct, and contains a fuel-burning appliance or a storage garage, or
(b)contains a residential occupancy and is served by a forced-air fuel-burning appliance not contained within the building.
(2)Articles 9.32.3.9B. and 9.32.3.9C. apply to every building.
Open OBC Div. B 9.32.3.9. in the code viewer
OBC Div. B 9.32.3.9A. Location of Carbon Monoxide Alarms
(1)A carbon monoxide alarm shall be installed in a suite of supply duct where
(a)a fuel-burning appliance or a flue is installed in the suite,
(b)a forced-air fuel-burning appliance provides heated air directly to the suite,
(c)a fuel-burning appliance or a flue is located in a room, suite or area that shares a common wall or floor or ceiling assembly with the suite, or
(d)a storage garage shares a common wall or floor or ceiling assembly with the suite.
(2)Where a carbon monoxide alarm is required by Sentence (1) to be installed in a suite of residential occupancy, other than a suite that consists of a combined living and sleeping area, a carbon monoxide alarm shall be installed
(a)adjacent to each sleeping room in the suite, and
(b)on each storey without a sleeping room in the suite.
(3)Where a carbon monoxide alarm is required by Sentence (1) to be installed in a suite of residential occupancy that consists of a combined living and sleeping area, a carbon monoxide alarm shall be installed in the combined living and sleeping area.
(4)In addition to the carbon monoxide alarms required to be installed in a suite of residential occupancy in accordance with Sentence (2), a carbon monoxide alarm shall be installed in each sleeping room within the suite where the sleeping room
(a)contains a fuel-burning appliance or a flue, or
(b)shares a common wall or floor or ceiling assembly
(i)with a room, suite or area that is located outside the suite and contains a fuel-burning appliance or a flue,
(ii)with a storage garage, or
(iii)that is adjacent to an attic or crawl space to which the storage garage is also adjacent.
(5)Carbon monoxide alarms shall be installed in public corridors serving suites of residential occupancy where the corridor is directly heated by a forced-air fuel-burning appliance.
(6)Where carbon monoxide alarms are required by Sentence (5) to be installed in a public corridor, the carbon monoxide alarms shall be installed such that
(a)there is at least one carbon monoxide alarm in each portion of a divided corridor, and
(b)each carbon monoxide alarm in an undivided portion of a corridor is spaced not more than 25 m apart.
Open OBC Div. B 9.32.3.9A. in the code viewer
OBC Div. B 9.32.3.9B. Location of Carbon Monoxide Alarms in All Buildings
(1)A carbon monoxide alarm shall be installed in service rooms or other areas of a building where the service room or other area
(a)contains a fuel-burning appliance used for building services or laundry drying equipment, and
(b)is not located within a suite of residential occupancy.
Open OBC Div. B 9.32.3.9B. in the code viewer
OBC Div. B 9.32.3.9C. Installation and Conformance to Standards
(1)The carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. shall
(a)except as permitted in Sentence (2), be permanently connected to an electrical circuit and shall have no disconnect switch between the overcurrent device and the carbon monoxide alarm,
(b)in case the regular power supply to the carbon monoxide alarm is interrupted, be provided with a battery as an alternative power source that can continue to provide power to the carbon monoxide alarm for a period of not less than 8 h in the standby condition, followed by the operation of the carbon monoxide alarm for an alarm signal for at least 12 h,
(c)be wired so that
(i)activation of one carbon monoxide alarm within a suite of residential occupancy will activate all carbon monoxide alarms within the suite,
(ii)activation of one carbon monoxide alarm within a house with a secondary suite will activate all carbon monoxide alarms within the house with a secondary suite including their common spaces, and
(iii)activation of one carbon monoxide alarm located in a public corridor serving suites of residential occupancy will activate all carbon monoxide alarms within the corridor.
(d)be audible within sleeping rooms when the intervening doors are closed, where located adjacent to a sleeping room in a suite of residential occupancy, and
(e)conform to
(i)CAN/CSA-6.19, "Residential Carbon Monoxide Alarming Devices," or
(ii)UL 2034, "Single and Multiple Station Carbon Monoxide Alarms."
(2)Where the building is not supplied with electrical power, carbon monoxide alarms are
(a)are permitted to be battery operated, and
(b)need not have a visual signaling component.
(3)Except as permitted in Sentence (2), the carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. shall have a visual signalling component conforming to the requirements in 18.5.3. (Light, Color and Pulse Characteristics) of NFPA 72, "National Fire Alarm and Signaling Code".
(4)The luminous intensity for visual signaling components required by Sentence (3) that are installed in sleeping rooms or combined living and sleeping areas shall be a minimum of 175 cd.
(5)The visual signaling component required by Sentence (3) need not
(a)be integrated with the carbon monoxide alarm provided it is interconnected to it,
(b)be on battery backup, or
(c)have synchronized flash rates, when installed in a dwelling unit.
(6)The carbon monoxide alarms required by Articles 9.32.3.9A. and 9.32.3.9B. shall be installed
(a)at the manufacturer's recommended height, or
(b)in the absence of specific instructions, on or near the ceiling.
Open OBC Div. B 9.32.3.9C. in the code viewer