Heating and air-conditioning systems (9.33.1 to 9.33.5)

Required heating systems and design temperatures

Scope OBC Div. B 9.33.1.1.OBC Div. B 9.33.1.1. Application(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…. Section 9.33. covers heating systems (including combustion air) and air-conditioning systems serving only one dwelling unit, plus radiant heating in a house with a secondary suite and its common spaces. Anything else (for example one forced-air system serving both units of a house with a secondary suite) follows Part 6. Two more rules in the same Article:

• Repairs or component replacements that change the capacity or safety of an existing system and alter how it operates must conform to the code.
• Air duct systems serving one unit of a house with a secondary suite must not be directly interconnected with other parts of the house.

Who needs heat. Residential buildings intended for use through the winter on a continuing basis must have heating facilities OBC Div. B 9.33.2.1.OBC Div. B 9.33.2.1. Residential Heating Systems(1) Residential buildings intended for use in the winter months on a continuing basis shall be equipped with heating facilities conforming to this Section..

Indoor design temperatures at the outside design temperature OBC Div. B 9.33.3.1.OBC Div. B 9.33.3.1. Indoor Design Temperatures(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…:

Outdoor design temperatures come from SB-1 using the 2.5 percent criteria OBC Div. B 9.33.3.2.OBC Div. B 9.33.3.2. Outdoor Design Temperatures(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..

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General requirements and system sizing

Design basis OBC Div. B 9.33.4.1.OBC Div. B 9.33.4.1. Design of Heating and Air-Conditioning Systems(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…. HVAC systems, including related refrigeration, must follow good engineering practice such as:

• ASHRAE Handbooks and Standards,
• CSA F280, "Determining the required capacity of residential space heating and cooling appliances", with outside winter design temperatures from SB-1,
• CAN/CSA-F326-M (residential mechanical ventilation),
• NFPA Standards, HRAI Digest, Hydronics Institute Manuals and SMACNA Manuals.

Sizing OBC Div. B 9.33.5.1.OBC Div. B 9.33.5.1. Capacity of Heating Appliances(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…:

What the candidate must know about F280. The code makes F280 the reference for residential heating and cooling capacity, and makes it the rule for how much a furnace or air conditioner may be oversized or undersized. The code does not reproduce F280's method, room-by-room factors or tolerances. On this exam, expect to identify that F280 governs equipment sizing, that SB-1 supplies the winter design temperature, and that sizing must be based on a calculated load (not on floor area rules of thumb). Questions that would need F280's internal numbers are outside the code text. Our question bank does not test them.

Other general rules:

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Appliances, equipment and installation standards

Earth energy systems OBC Div. B 9.33.5.2.OBC Div. B 9.33.5.2. Installation Standards (See also Article 9.33.5.3.)(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…. Systems using groundwater, submerged or ground heat exchangers that serve a house (with or without a secondary unit), or another building with not more than 1,400 m² of conditioned space, follow CAN/CSA-C448.2. Buildings other than houses conditioning more than 1,400 m² follow C448.1.

Solid-fuel appliances OBC Div. B 9.33.5.3.OBC Div. B 9.33.5.3. Design, Construction and Installation Standard for Solid-Fuel-Burning 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)…. Design, construction and installation, including combustion air, of stoves, cooktops, ovens and space heaters burning solid fuel follow CSA B365. Solid-fuel stoves, furnaces and hydronic systems (other than coal-burning) must meet particulate emission limits of CSA B415.1 or the US EPA new residential wood heater standard.

Fireplaces conform to Section 9.22. OBC Div. B 9.33.5.4.OBC Div. B 9.33.5.4. Fireplaces(1) Fireplaces shall conform to Section 9.22..

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