Last updated
Values this chapter turns on
- Part 6 indoor design temperature, residential
- 22°C
- Part 6 indoor design temperature, residential
- conditioned space limit for C448.2, non-houses
- 1,400 m²
- conditioned space limit for C448.2, non-houses
- max air or surface temperature in a fuel storage bin
- 50°C
- max air or surface temperature in a fuel storage bin
Part 6 is the HVAC Part for buildings outside Part 9, but a house designer still needs it. Section 9.33. sends systems that serve more than one dwelling unit (other than radiant heating in a house with a secondary suite) to Part 6, and Part 9 borrows many Part 6 ideas word for word. This chapter covers Sections 6.1. and 6.2.
Application and definitions
Part 6 applies to systems and equipment for heating, ventilating and air-conditioning services OBC Div. B 6.1.1.2.OBC Div. B 6.1.1.2. Application(1) This Part applies to systems and equipment for heating, ventilating and air-conditioning services.. Its scope is set by Subsection 1.3.3. of Division A OBC Div. B 6.1.1.1.OBC Div. B 6.1.1.1. Scope(1) The scope of this Part shall be as described in Subsection 1.3.3. of Division A. (2) Where the method of operation of an existing heating, ventilating or air-conditioning system is altered, the repair or component replacements that change the capacity or extent of safety of the system shall conform to this Code….
Alterations to existing systems. Where the method of operation of an existing HVAC system is altered, any repair or component replacement that changes the capacity or the extent of safety of the system must conform to the code OBC Div. B 6.1.1.1.OBC Div. B 6.1.1.1. Scope(1) The scope of this Part shall be as described in Subsection 1.3.3. of Division A. (2) Where the method of operation of an existing heating, ventilating or air-conditioning system is altered, the repair or component replacements that change the capacity or extent of safety of the system shall conform to this Code…. Part 9 has the same rule in Sentence 9.33.1.1.(2.1). In plain terms: swapping a furnace for an identical one is maintenance; changing the system in a way that alters how it operates and its capacity or safety brings the code back in.
Italic words in Part 6 are defined in Article 1.4.1.2. of Division A OBC Div. B 6.1.2.1.OBC Div. B 6.1.2.1. Defined Terms(1) Words that appear in italics are defined in Article 1.4.1.2. of Division A..
Design, design temperatures and installation standards
Good engineering practice. HVAC systems, including mechanical refrigeration equipment, must be designed, built and installed to good engineering practice. The code gives a non-exhaustive list of sources OBC Div. B 6.2.1.1.OBC Div. B 6.2.1.1. Good Engineering Practice(1) Heating, ventilating and air-conditioning systems, including mechanical refrigeration equipment, shall be designed, constructed and installed in conformance with good engineering practice such as that described in, but not limited to, (a) the ASHRAE Handbooks and Standards, (b) the HRAI Digest, (c) the Hydronics…:
- ASHRAE Handbooks and Standards
- HRAI Digest
- Hydronics Institute Manuals
- NFPA Standards
- SMACNA Manuals
- ACGIH "Industrial Ventilation" manual
- CSA B214 (hydronic heating)
- CAN/CSA-Z317.2 (health care HVAC)
- EPA radon guidance for large buildings
- ASHRAE Guideline 12 (legionellosis)
You need to know that these are named, and in which Article, not their content.
Design indoor temperature. Group B, Division 2 or 3 buildings and Group C residential buildings used through the winter must be insulated and heated to maintain 22°C at the outside winter design temperature OBC Div. B 6.2.1.1A.OBC Div. B 6.2.1.1A. Design Indoor Air Temperatures(1) Buildings classified as Group B, Division 2 or 3 occupancies or Group C residential occupancies that are intended for use in the winter months on a continuing basis shall be insulated and be equipped with heating facilities that are capable of maintaining an indoor air temperature of 22°C at the outside winter…. Sentence (2) of that Article (other buildings, 18°C) is excluded from this exam's syllabus.
Outdoor design conditions. Use SB-1 OBC Div. B 6.2.1.2.OBC Div. B 6.2.1.2. Outdoor Design Conditions(1) The outdoor conditions to be used in designing heating, ventilating and air-conditioning systems shall be determined in conformance with MMAH Supplementary Standard SB-1, "Climatic and Seismic Data.".
Other general design rules:
| Article | Requirement in plain words |
|---|---|
| 6.2.1.3.OBC Div. B 6.2.1.3. Expansion, Contraction and System Pressure(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. | Allow for expansion and contraction of the heat transfer fluid; keep pressure within rated working limits of all components |
| 6.2.1.4.OBC Div. B 6.2.1.4. Structural Movement(1) Mechanical systems and equipment shall be designed and installed to accommodate the maximum relative structural movement provided for in the construction of the building. | Accommodate the maximum relative structural movement built into the building |
| 6.2.1.6.OBC Div. B 6.2.1.6. Installation — General(1) Equipment requiring periodic maintenance and forming part of a heating, ventilating or air-conditioning system shall be installed with provision for access for inspection, maintenance, repair and cleaning. (See Note A-6.2.1.6.(1)) (2) Mechanical equipment shall be provided with guards so as to prevent injury. (3)… | Access for inspection, maintenance, repair and cleaning; guards on mechanical equipment; freeze protection |
| 6.2.1.7.OBC Div. B 6.2.1.7. Asbestos(1) Asbestos shall not be used in heating, ventilating or air-conditioning systems or equipment. | No asbestos in HVAC systems or equipment |
Installation standards OBC Div. B 6.2.1.5.OBC Div. B 6.2.1.5. Installation Standards(1) The installation of solid fuel-burning appliances for central heating systems shall comply with CSA B365, "Installation code for solid-fuel-burning appliances and equipment" and the manufacturer's installation instructions. (2) The solid fuel-fired appliances in Sentence (1) shall conform to CSA B366.1…. The code points to installation standards by appliance type:
| System | Standard named |
|---|---|
| Solid-fuel central heating appliances | CSA B365 for installation, plus manufacturer's instructions; appliance itself to CSA B366.1 |
| Earth energy, house (with or without a secondary unit) or other building with conditioned space not more than 1,400 m² | CAN/CSA-C448.2 |
| Solid-fuel stoves, ranges and space heaters, including combustion air | CSA B365 plus manufacturer's instructions |
| Hydronic heating | CSA B214, or good engineering practice under 6.2.1.1. |
| Solid-fuel stoves, furnaces and hydronic systems (other than coal) | Particulate emission limits of CSA B415.1 or the US EPA wood heater standard |
Sentence 6.2.1.5.(4) (C448.1 for large commercial earth energy systems) is excluded from the syllabus, so expect questions on the C448.2 threshold instead. Article 6.2.1.8. (combustible tubing) is also excluded.
These standards are external documents. The exam tests that the code requires them and when they apply. It does not test what is inside them.
Incinerators and solid fuel storage
- Every indoor incinerator must be designed, built, installed and materially altered to NFPA 82 OBC Div. B 6.2.2.1.OBC Div. B 6.2.2.1. Applicable Standard(1) The design, construction, installation and material alteration of every indoor incinerator shall conform to NFPA 82, "Standard on Incinerators and Waste and Linen Handling Systems and Equipment.".
- A solid fuel storage bin must not be located above a sewer opening or drain opening, and must keep the air in the bin and the surface temperature of its floor and walls below 50°C OBC Div. B 6.2.3.1.OBC Div. B 6.2.3.1. Solid Fuel Storage Bins(1) A storage bin for solid fuel shall not be located above a sewer opening or drain opening. (2) Storage bins for solid fuel shall be designed and constructed so that the air temperature in the bin or the surface temperature of any part of the floor or walls is below 50°C..
Common traps
- Quoting 18°C as the Part 6 design temperature for a residential building. For Group C the figure is 22°C.
- Assuming C448.2 has an area limit for houses. The 1,400 m² cap applies to buildings other than a house.
- Reading the good-practice list as closed. The code says "not limited to".
- Forgetting that changing the capacity or safety of an existing system (with an altered method of operation) triggers compliance.
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.
- Application and definitions
Part 6 applies to systems and equipment for heating, ventilating and air-conditioning services.
- Design, design temperatures and installation standards
You need to know that these are named, and in which Article, not their content.
Usual exam traps
- Quoting 18°C as the Part 6 design temperature for a residential building. For Group C the figure is 22°C.
- Assuming C448.2 has an area limit for houses. The 1,400 m² cap applies to buildings other than a house.
- Reading the good-practice list as closed. The code says "not limited to".
- Forgetting that changing the capacity or safety of an existing system (with an altered method of operation) triggers compliance.
Practice this chapter
Questions on Part 6: general, design and installation, in the exam format, every answer explained and cited to its article. Sign in to start; a free account gets the free questions.
Code cited in this chapter
Based on the official 2024 Building Code Compendium on ontario.ca.
© King's Printer for Ontario, 2024. Reproduced with permission.
OBC Div. B 6.1.1.2. Application
Open OBC Div. B 6.1.1.2. in the code viewer(1)This Part applies to systems and equipment for heating, ventilating and air-conditioning services.
OBC Div. B 6.1.1.1. Scope
Open OBC Div. B 6.1.1.1. in the code viewer(1)The scope of this Part shall be as described in Subsection 1.3.3. of Division A.
(2)Where the method of operation of an existing heating, ventilating or air-conditioning system is altered, the repair or component replacements that change the capacity or extent of safety of the system shall conform to this Code. (See Note A-6.1.1.1.(2))
OBC Div. B 6.1.2.1. Defined Terms
Open OBC Div. B 6.1.2.1. in the code viewer(1)Words that appear in italics are defined in Article 1.4.1.2. of Division A.
OBC Div. B 6.2.1.1. Good Engineering Practice
Open OBC Div. B 6.2.1.1. in the code viewer(1)Heating, ventilating and air-conditioning systems, including mechanical refrigeration equipment, shall be designed, constructed and installed in conformance with good engineering practice such as that described in, but not limited to,
(a)the ASHRAE Handbooks and Standards,
(b)the HRAI Digest,
(c)the Hydronics Institute Manuals,
(d)the NFPA Standards,
(e)the SMACNA Manuals,
(f)the ACGIH manual entitled "Industrial Ventilation: A Manual of Recommended Practice for Design,"
(g)CSA B214, "Installation code for hydronic heating systems,"
(h)CAN/CSA-Z317.2, "Special requirements for heating, ventilation, and air-conditioning (HVAC) systems in health care facilities,"
(i)EPA 625/R-92/016, "Radon Prevention in the Design and Construction of Schools and Other Large Buildings," and
(j)ASHRAE Guideline 12, "Minimizing the Risk of Legionellosis Associated with Building Water Systems."
OBC Div. B 6.2.1.1A. Design Indoor Air Temperatures
Open OBC Div. B 6.2.1.1A. in the code viewer(1)Buildings classified as Group B, Division 2 or 3 occupancies or Group C residential occupancies that are intended for use in the winter months on a continuing basis shall be insulated and be equipped with heating facilities that are capable of maintaining an indoor air temperature of 22°C at the outside winter design temperature referred to in Article 6.2.1.2.
(2)All other buildings intended for occupancy in the winter months on a continuing basis should be insulated and shall be equipped with heating facilities to maintain a minimum indoor air temperature of 18°C or commensurate with the use of the building at the outside winter design temperature described in Article 6.2.1.2.
OBC Div. B 6.2.1.2. Outdoor Design Conditions
Open OBC Div. B 6.2.1.2. in the code viewer(1)The outdoor conditions to be used in designing heating, ventilating and air-conditioning systems shall be determined in conformance with MMAH Supplementary Standard SB-1, "Climatic and Seismic Data."
OBC Div. B 6.2.1.3. Expansion, Contraction and System Pressure
Open OBC Div. B 6.2.1.3. in the code viewer(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.
OBC Div. B 6.2.1.4. Structural Movement
Open OBC Div. B 6.2.1.4. in the code viewer(1)Mechanical systems and equipment shall be designed and installed to accommodate the maximum relative structural movement provided for in the construction of the building.
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OBC Div. B 6.2.1.6. Installation — General
Open OBC Div. B 6.2.1.6. in the code viewer(1)Equipment requiring periodic maintenance and forming part of a heating, ventilating or air-conditioning system shall be installed with provision for access for inspection, maintenance, repair and cleaning. (See Note A-6.2.1.6.(1))
(2)Mechanical equipment shall be provided with guards so as to prevent injury.
(3)Heating, ventilating or air-conditioning systems shall be protected from freezing if they may be adversely affected by freezing temperatures.
OBC Div. B 6.2.1.7. Asbestos
Open OBC Div. B 6.2.1.7. in the code viewer(1)Asbestos shall not be used in heating, ventilating or air-conditioning systems or equipment.
OBC Div. B 6.2.1.5. Installation Standards
Open OBC Div. B 6.2.1.5. in the code viewer(1)The installation of solid fuel-burning appliances for central heating systems shall comply with CSA B365, "Installation code for solid-fuel-burning appliances and equipment" and the manufacturer's installation instructions.
(2)The solid fuel-fired appliances in Sentence (1) shall conform to CSA B366.1, "Solid-fuel-fired central heating appliances."
(3)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, other than a house with or without a secondary unit, where the conditioned space is not more than 1,400 m².
(4)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.
(5)The design and installation of solid fuel-burning stoves, ranges and space heaters, including the requirements for combustion air, shall conform to the requirements of CSA B365, "Installation code for solid-fuel-burning appliances and equipment" and the manufacturer's installation instructions.
(6)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 6.2.1.1.
(7)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.
OBC Div. B 6.2.2.1. Applicable Standard
Open OBC Div. B 6.2.2.1. in the code viewer(1)The design, construction, installation and material alteration of every indoor incinerator shall conform to NFPA 82, "Standard on Incinerators and Waste and Linen Handling Systems and Equipment."
OBC Div. B 6.2.3.1. Solid Fuel Storage Bins
Open OBC Div. B 6.2.3.1. in the code viewer(1)A storage bin for solid fuel shall not be located above a sewer opening or drain opening.
(2)Storage bins for solid fuel shall be designed and constructed so that the air temperature in the bin or the surface temperature of any part of the floor or walls is below 50°C.