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OBC HVAC - House practice questions

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Question 1Administration, definitions and scope of the Building Code Act / OBC

In Ontario, what is the legal nature of the Ontario Building Code?

  1. A statute enacted by the Legislative Assembly of Ontario
  2. A regulation made under the Building Code Act, 1992 Correct answer.
  3. A policy guideline issued by the chief building official
  4. A municipal by-law adopted by each local council

Explanation

The Building Code Act, 1992 is the statute, and the Ontario Building Code is a regulation made under it. The Act supplies the administrative framework, including permits, enforcement and offences, while the code contains the technical requirements. A municipal by-law or an official's guideline cannot replace either instrument.

Question 2Administration, definitions and scope of the Building Code Act / OBC

Under the Building Code Act, 1992, a structure with a wall, roof and floor is a "building" only if it occupies an area greater than what threshold, unless it contains plumbing?

  1. Five square metres
  2. Fifty square metres
  3. Twenty square metres
  4. Ten square metres Correct answer.

Explanation

The definition in section 1(1) sets the general threshold at ten square metres for a structure consisting of a wall, roof or floor, or any of them, or a structural system serving that function. A structure of ten square metres or less is still a building if it contains plumbing, and plumbing not located in a structure is itself treated as a building.

Question 3Administration, definitions and scope of the Building Code Act / OBC

Who is responsible for appointing a municipality's chief building official under the Building Code Act, 1992?

  1. The Minister of Municipal Affairs and Housing
  2. The Building Code Commission
  3. The registered code agency for the area
  4. The council of the municipality Correct answer.

Explanation

Section 3 requires the council of each municipality to appoint a chief building official and the inspectors necessary to enforce the Act and the building code. The Minister administers the Act province-wide but does not make local appointments. The appointed chief building official then exercises the powers and duties conferred by the Act.

Question 4Administration, definitions and scope of the Building Code Act / OBC

Which activities fall within the scope of the Building Code Act, 1992?

  1. Construction and demolition of buildings, plumbing, and changes of use Correct answer.
  2. Only demolition and renovation work whose value exceeds an amount set by by-law
  3. Only the construction of new residential buildings
  4. Only buildings owned or occupied by a municipality

Explanation

Section 2 provides that the Act applies to the construction and demolition of buildings, to plumbing, and to the change of use of buildings. Coverage is not limited by building type, ownership or project value. Where the Act applies, the technical standards of the building code must be satisfied.

Question 5Administration, definitions and scope of the Building Code Act / OBC

Which set of objectives does the Building Code Act, 1992 direct the building code to establish minimum standards for?

  1. Resale value, aesthetic design, neighbourhood character and zoning density limits
  2. Labour rates, construction scheduling, warranty terms and bonding requirements
  3. Property tax assessment, zoning compliance, lot coverage and parking ratios
  4. Health and safety, accessibility, environmental integrity and energy efficiency Correct answer.

Explanation

Section 5 states the objects of the building code, which include minimum standards of health and safety, accessibility, environmental integrity and energy efficiency, among related public-interest goals. These objects guide the content of the code and how its provisions are interpreted. Private commercial interests and municipal planning controls are not code objectives.

Question 6Administration, definitions and scope of the Building Code Act / OBC

A homeowner plans to demolish a detached garage in an Ontario municipality. Under the Building Code Act, 1992, what must happen before demolition begins?

  1. Approval is needed only if the garage exceeds ten square metres
  2. Nothing, because demolition is exempt from the Act
  3. Only a written notice to the local utility is required
  4. A building permit must be obtained for the demolition Correct answer.

Explanation

Section 8 prohibits the construction or demolition of a building without a permit issued by the chief building official, unless the building code exempts the work. Demolition of a garage that meets the definition of a building therefore requires a permit. The obligation rests on the person doing the work, not on utilities or neighbours.

Question 7Administration, definitions and scope of the Building Code Act / OBC

An owner wants to convert the upper floor of a retail store into residential apartments. Under the Building Code Act, 1992, how is this treated?

  1. Only a zoning amendment from the municipality, with no building code review
  2. It requires a demolition permit before any work may start
  3. A change of use, which must comply with the code for the new use Correct answer.
  4. It is exempt because no new construction is proposed

Explanation

Section 10 addresses changes in the use of a building and requires that the building be evaluated against the code requirements applicable to the proposed new use. A change from mercantile to residential occupancy commonly triggers upgrades such as fire separations, exiting and plumbing. Zoning approval may also be needed, but it does not replace the code review.

Question 8Administration, definitions and scope of the Building Code Act / OBC

An application, plans and fees are complete, and the proposal complies with the Act, the building code and other applicable law. What is the chief building official required to do?

  1. Issue the permit Correct answer.
  2. Refer the application to council for a vote
  3. Hold the permit until the Building Code Commission reviews it
  4. Refuse the permit until neighbouring owners consent

Explanation

The Act makes issuance mandatory where the application is complete and the proposed work complies with the Act, the building code and any other applicable law. The chief building official has no discretion to refuse for reasons outside those statutory criteria. Requiring neighbour consent or a council vote would add conditions the Act does not authorize.

Question 9Administration, definitions and scope of the Building Code Act / OBC

A contractor installs a complete plumbing system in a small storage shed that is under ten square metres and is not connected to any other building. Which statement best reflects the Act?

  1. The work is exempt because the structure is not a dwelling
  2. The work is "construction" and requires a permit Correct answer.
  3. The work is exempt because the shed is used only for storage
  4. The work is exempt because the shed is under ten square metres

Explanation

The Act defines construction to include plumbing and anything for which a permit is required, and a structure of ten square metres or less that contains plumbing is expressly a building. Storage use and dwelling status do not create exemptions from the plumbing requirements. A permit is therefore needed before the plumbing work begins.

Question 10Administration, definitions and scope of the Building Code Act / OBC

What is the role of the Building Code Commission under the Building Code Act, 1992?

  1. It prosecutes offences under the Act in the Ontario Court of Justice
  2. It appoints chief building officials for municipalities that lack one
  3. It decides disputes about whether materials or systems comply Correct answer.
  4. It writes and amends the technical provisions of the building code

Explanation

The Building Code Commission is established by the Act to decide disputes about the sufficiency of compliance of materials, systems or designs with the building code. It does not write the code, appoint officials or prosecute offences; those functions belong to the Minister, municipal councils and the courts respectively. Its decisions resolve specific technical disagreements referred to it.

Question 11Administration, definitions and scope of the Building Code Act / OBC

Under the Building Code Act, 1992, which of the following persons falls within the statutory definition of an "owner" of a building?

  1. A purchaser who has signed an agreement of purchase and sale but has not yet closed
  2. A lessee who holds a lease and has charge or control of the building Correct answer.
  3. A contractor who has been hired to renovate the building under a fixed-price contract
  4. An architect who prepared the drawings and supervises the construction

Explanation

The Act defines owner broadly so that it covers anyone with a legal or possessory interest in the building or land, including a lessee, a mortgagee in possession, a person in charge or control, and the beneficial owner. Duties such as obtaining permits and complying with orders attach to that wider group, not only to the registered title holder.

Question 12Administration, definitions and scope of the Building Code Act / OBC

Within a municipality in Ontario, who bears the statutory responsibility for administering and enforcing the Building Code Act, 1992 and the building code?

  1. The local board of health for the area
  2. The council of the municipality Correct answer.
  3. The Minister of Municipal Affairs and Housing, acting alone
  4. The Building Code Commission

Explanation

The Act places responsibility for local administration and enforcement on the council of each municipality, which then appoints a chief building official and inspectors to carry out the work. The Minister's role is provincial oversight and the Building Code Commission hears appeals rather than running day-to-day enforcement.

Question 13Administration, definitions and scope of the Building Code Act / OBC

A municipal inspector has reasonable grounds to believe that a warehouse is being altered without a permit. What authority does the inspector have under the Building Code Act, 1992?

  1. Enter only when accompanied by a municipal police officer
  2. Enter only after a justice of the peace issues a search warrant
  3. Enter only with the written consent of the registered owner
  4. Enter and inspect at any reasonable time without a warrant Correct answer.

Explanation

The Act gives an inspector the power to enter and inspect land or buildings at any reasonable time without a warrant for the purpose of determining whether the Act and code are being complied with. The inspector must produce identification on request, and may be accompanied by a police officer where needed, but consent and a warrant are not preconditions for a routine inspection of a non-residential building.

Question 14Administration, definitions and scope of the Building Code Act / OBC

A proposed sewage system will serve a small commercial plaza. Under the Building Code Act, 1992, the Act regulates the system only where:

  1. It serves fewer than five plumbing fixtures in total at the time of installation
  2. It discharges into a municipal sanitary sewer system owned by the town
  3. It is located outside a settlement area boundary designated in an official plan
  4. Its total capacity is 10,000 litres per day or less Correct answer.

Explanation

The Act's definition of a sewage system is limited by capacity: systems with a total design capacity of 10,000 litres per day or less fall within the building code regime, while larger systems are dealt with under provincial environmental legislation. Capacity, not fixture count, sewer connection or geographic location, is the test that fixes the boundary.

Question 15Administration, definitions and scope of the Building Code Act / OBC

An apartment building constructed in 1975 complied with the code in force at the time but does not meet several current requirements. The owner proposes no work of any kind. Which statement best reflects the law under the Building Code Act, 1992?

  1. Nothing must be done unless the owner constructs, changes use, or an unsafe condition exists Correct answer.
  2. The building must be vacated until it complies with the current code
  3. The owner must upgrade the whole building to current standards within one year
  4. The owner must immediately upgrade the fire separations and exits throughout

Explanation

The Act and the building code set minimum standards for new construction and for defined work on existing buildings; they are not applied retrospectively to compel blanket upgrading of buildings that complied when built. Duties are triggered by construction, demolition, a change of use that increases hazard, or the existence of an unsafe condition, so an owner who undertakes no work owes no general retrofit obligation.

Question 16Administration, definitions and scope of the Building Code Act / OBC

Which statement best describes the legal relationship between the Building Code Act, 1992, the building code, and a municipal by-law?

  1. The Act contains technical construction requirements while the code sets out the enforcement procedures
  2. All three instruments are statutes passed by the Legislature and each carries the same legal weight
  3. The Act is a statute, the code is a regulation under it, and by-laws cannot weaken the code Correct answer.
  4. A municipal by-law that conflicts with the building code prevails over the code within the municipality that passed the by-law

Explanation

The Building Code Act, 1992 is a statute of the Legislature, and the building code is a regulation made under it, so the technical content can be amended without amending the Act. Municipalities are responsible for local administration and may pass by-laws on procedural matters, but a by-law cannot relax the minimum standards fixed by the code.

Question 17General provisions, referenced standards and permits/inspection requirements

The Ontario Building Code, which governs the installation of heating, ventilating and air-conditioning systems in houses, is best described as which of the following?

  1. A voluntary industry standard published by CSA Group
  2. A regulation made under the Building Code Act, 1992 Correct answer.
  3. A municipal by-law adopted separately by each municipality
  4. A federal statute administered by the National Research Council

Explanation

The Building Code Act, 1992 is the statute, and the Ontario Building Code is the regulation made under it (Ontario Regulation 332/12). The Code is enforced by municipal chief building officials; a municipality may pass related by-laws, but it cannot relax or waive Code requirements. Referenced standards form part of the Code only because the Code adopts them.

Question 18General provisions, referenced standards and permits/inspection requirements

Which referenced standard sets out the installation requirements for a natural gas-fired furnace and its gas piping in a house?

  1. CAN/CSA-C22.1
  2. CAN/CSA-B149.1 Correct answer.
  3. CAN/CSA-B139
  4. CAN/CSA-F326

Explanation

CAN/CSA-B149.1, the Natural Gas and Propane Installation Code, is the standard adopted by the Ontario Building Code for the installation of gas-burning appliances, their venting and their gas piping. It addresses clearances, combustion air, venting and testing of the gas train for residential furnaces. Installers working in Ontario are also licensed under the Technical Standards and Safety Act.

Question 19General provisions, referenced standards and permits/inspection requirements

Ductwork and furnace venting in a house will be permanently enclosed in a soffit. What must the permit holder do before the assemblies are covered?

  1. Obtain the equipment manufacturer's written approval of the concealed location
  2. Notify the inspector that the work is ready for inspection and obtain clearance before concealing it Correct answer.
  3. Submit as-built drawings to the chief building official after the work is finished
  4. Photograph the installation and keep the photographs on the site for the owner

Explanation

The Building Code Act requires the permit holder to notify the chief building official when work is ready for inspection and prohibits covering work before it has been inspected. Work that is concealed without inspection may have to be exposed again at the permit holder's expense. Photographs and manufacturer approvals do not satisfy the inspection requirement.

Question 20General provisions, referenced standards and permits/inspection requirements

A building permit for a furnace and ductwork installation in a house was issued on 1 March. By 1 October of the same year, none of the work has started and the chief building official has not been notified. What is the status of the permit?

  1. It has expired because the work was not commenced within six months Correct answer.
  2. It renews automatically for a further twelve months
  3. It remains valid until the date the project is expected to be completed
  4. It converts into a notice of violation against the property

Explanation

Under the Building Code Act a permit expires if the work is not commenced within six months after it is issued, unless the chief building official is notified before that period ends and the work will begin. Starting the work is what keeps the permit alive; the permit does not track an estimated completion date. A new application would be needed to proceed lawfully after expiry.

Question 21General provisions, referenced standards and permits/inspection requirements

Who may be issued a building permit for HVAC work in a house?

  1. Only a designer registered with the province as a professional engineer
  2. Only the licensed HVAC contractor who will actually perform the work
  3. Any person the owner has given verbal permission to act for them
  4. The owner of the property or a person the owner has authorized in writing Correct answer.

Explanation

The Building Code Act allows a permit to be issued to the owner or to an agent authorized by the owner, and the authorization should be in writing so the chief building official can verify it. Where the agent prepares the design for a house, that person must also be qualified under the Code's designer requirements. The contractor performing the work need not be the permit holder.

Question 22General provisions, referenced standards and permits/inspection requirements

Which referenced standard does the Ontario Building Code adopt for the design and installation of mechanical ventilation systems in a single-family house?

  1. CSA B139
  2. CSA F326 Correct answer.
  3. CSA B44
  4. ASHRAE Standard 62.1

Explanation

CSA F326, Residential mechanical ventilation systems, is the standard the Code points to for sizing, balancing and installing ventilation systems in dwellings. It works together with the Code's own requirements for outdoor air supply, exhaust and make-up air in houses. Compliance with it is normally demonstrated through the ventilation design and the commissioning record.

Question 23General provisions, referenced standards and permits/inspection requirements

An installer finds that a requirement in CSA B149.1 differs from a provision of the Ontario Building Code that deals with the same matter. Which document governs?

  1. The Ontario Building Code, because the Code prevails where there is a conflict Correct answer.
  2. The appliance manufacturer's installation instructions, in every case
  3. The referenced standard, because it is the more technically detailed document
  4. Neither document; the installer may choose the less onerous requirement

Explanation

Referenced standards are given force only through the Code, so where a standard and the Code conflict, the Code governs. The installer must still meet the standard wherever the Code is silent or simply refers to it. Manufacturer's instructions must also be followed, but they cannot override a Code requirement.

Question 24General provisions, referenced standards and permits/inspection requirements

A house's HVAC system is designed by a consultant hired directly by the owner rather than by the installing contractor. Which qualification must that designer hold for this house?

  1. A Building Code Identification Number in the appropriate category, such as House Correct answer.
  2. A professional engineer's seal on every sheet of the design
  3. Current membership in a heating and air-conditioning trade association
  4. Registration with the Ontario Association of Architects

Explanation

The Code requires that a person who prepares design work for a building be qualified, and for houses that generally means holding a Building Code Identification Number in the House category. Architects and engineers are among the practitioners who may qualify, but simply being one does not by itself satisfy the registration requirement. Trade association membership is not a Code qualification.

Question 25General provisions, referenced standards and permits/inspection requirements

A contractor is engaged to replace a gas-fired furnace and to modify the supply ductwork in an existing single-family house. Which statement describes the permit obligation?

  1. No permit is required because the work amounts to repairing existing equipment
  2. A gas permit from the provincial fuels safety authority is sufficient on its own
  3. A building permit must be obtained before work begins and the work must be inspected at the required stages Correct answer.
  4. The permit may be obtained at any time before the house is next occupied

Explanation

Altering a house's heating system, including installing equipment and reworking ductwork, is construction that requires a building permit before the work starts, and the permit holder must call for the inspections the chief building official requires. A fuels safety permit is a separate approval and does not substitute for the building permit. Obtaining a permit after the work is done leaves the work unpermitted during construction.

Question 26General provisions, referenced standards and permits/inspection requirements

Which of the following is exempt from the requirement to obtain a building permit under the Building Code Act, 1992?

  1. A farm building that is not used for residential or business purposes Correct answer.
  2. An attached garage forming part of a new house
  3. A furnace replacement in a rented house
  4. A new detached single-family house

Explanation

The Building Code Act lists classes of work that do not require a permit, and a farm building that is not used for residential or business purposes falls within those exemptions, along with small accessory structures and certain temporary buildings. Dwellings, garages attached to dwellings and HVAC alterations in residential buildings are not exempt. Exemption from a permit does not exempt the work from complying with the Code where it applies.

Question 27General provisions, referenced standards and permits/inspection requirements

While HVAC work authorized by a building permit is being carried out in a house, what must the permit holder have on the site?

  1. The contractor's original business licence and photo identification
  2. A signed copy of the homeowner's property insurance policy
  3. The manufacturer's installation manual for each appliance
  4. A copy of the permit posted conspicuously on site Correct answer.

Explanation

The Building Code Act, 1992 requires the holder of a building permit to keep a copy of the permit posted in a conspicuous place on the premises while the work is being carried out. Posting it lets the inspector, the owner and anyone else on site confirm that the work is authorized. Only the permit itself satisfies this requirement.

Question 28General provisions, referenced standards and permits/inspection requirements

A designer is sizing the furnace and cooling coil for a new house. Which referenced standard does the Ontario Building Code require to be used to determine the required heating and cooling capacity?

  1. CSA C22.1
  2. CSA F326
  3. CSA B149.1
  4. CSA F280 Correct answer.

Explanation

The Building Code adopts CSA F280 for calculating the heating and cooling loads used to select residential space-conditioning equipment, so a furnace must be sized from a proper load calculation rather than a rule of thumb. The other documents listed deal with gas installation, ventilation design and electrical work respectively.

Question 29General provisions, referenced standards and permits/inspection requirements

Midway through an installation, a contractor decides to install a different furnace model than the one described in the documents filed with the building permit application. What is the correct course of action?

  1. Proceed, because equipment selection is a field decision for the installing contractor
  2. Submit revised documents to the chief building official for acceptance before proceeding Correct answer.
  3. Record the substitution in the owner's maintenance file and report it at the time of the final inspection
  4. Proceed, provided the replacement furnace carries the same certification mark

Explanation

The permit is issued on the basis of the plans and specifications filed with the application, so substituting a different appliance is a material change to what was approved. The permit holder must submit revised documents and have the change accepted by the chief building official before the new equipment is installed.

Question 30General provisions, referenced standards and permits/inspection requirements

How does a standard that is referenced in the Ontario Building Code affect an HVAC installation in a house?

  1. It applies only where the designer has named it in the project specifications
  2. It is non-binding guidance that the inspector may consider at their discretion
  3. It has no legal effect unless the local municipality passes a by-law adopting it
  4. It forms part of the Code's requirements, and compliance with it is mandatory Correct answer.

Explanation

Standards referenced in the Building Code are incorporated by reference, which means their requirements are enforceable as part of the Code itself. An HVAC system must therefore satisfy both the Code's own provisions and the referenced standards it points to, whether or not the municipality has taken any further step.

Question 31Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Fuel-fired heating appliances in a house require a supply of combustion air. What is the primary purpose of providing this air?

  1. To cool the appliance casing during normal operation
  2. To humidify the flue gases before they leave the vent
  3. To pressurize the house and reduce infiltration
  4. To support combustion and maintain proper draft Correct answer.

Explanation

Combustion air is the air supplied to the burner for burning fuel and to establish draft. Without an adequate supply, a fuel-fired appliance can burn incompletely, produce carbon monoxide, and spill flue gases into the house. Cooling the casing, pressurizing the house, and humidifying flue gases are not the purpose of combustion air.

Question 32Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Where should the outdoor air intake of a house ventilation system be located?

  1. Away from exhaust outlets, plumbing vents, and other contamination sources Correct answer.
  2. Directly above the furnace flue terminal to use rising warm air
  3. Inside the attached garage to temper the incoming air
  4. Below the basement floor slab to pre-cool the air

Explanation

Outdoor air intakes must be located where they will not draw in contaminated air. Exhaust outlets, plumbing vents, and similar sources can discharge odours and pollutants that would then be distributed through the house. Garage air and air from beneath the slab are also unsuitable because they can contain vehicle exhaust or soil gases.

Question 33Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Unless the appliance is listed for reduced clearance, what must be maintained between a fuel-fired furnace vent connector and combustible material?

  1. The clearance specified in the appliance or vent listing Correct answer.
  2. A clearance of 25 mm (1 in.) in all directions
  3. No clearance is needed, provided the connector is single-wall metal
  4. A clearance equal to the connector diameter

Explanation

Vent connectors and appliances must be installed with the clearance to combustible material specified in their listing or the code. The listing accounts for the heat produced by that particular appliance or vent. Reducing the clearance can overheat nearby wood and create a fire hazard, and single-wall connectors generally require a defined clearance.

Question 34Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A fuel-fired furnace is installed in a small, enclosed furnace room in a house. How is combustion air normally supplied to the room under Part 6?

  1. By a duct connected to the return-air plenum of the furnace
  2. By leaving the furnace room door permanently open to the basement
  3. By permanent openings or ducts to an adequate air source Correct answer.
  4. By a single opening at ceiling level sized to the flue area

Explanation

A furnace located in a confined space needs a reliable supply of combustion air. Permanent openings or ducts connecting the room to an adequate air source provide that supply without relying on open doors or return-air systems. A single ceiling opening or a return-air connection does not reliably supply air and can cause depressurization.

Question 35Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A natural-draft gas furnace is connected to a vertical vent. How should the vent connector be installed?

  1. Sloping upward toward the vent and properly supported Correct answer.
  2. Sloping upward away from the vent to improve draft
  3. Horizontal with no slope, provided it is short
  4. Sloping downward toward the furnace to drain condensation

Explanation

Vent connectors for natural-draft appliances must slope upward toward the vent so flue gases rise freely. Proper support keeps the required slope and prevents sagging that could collect condensate or obstruct flow. Downward slope, horizontal runs, or reverse slope can trap gases and cause spillage.

Question 36Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

How should flexible ductwork for a house heating system be installed?

  1. Supported only at the furnace end and left to hang
  2. Fully extended, supported, and bent without sharp kinks Correct answer.
  3. Compressed lengthwise to fit tight spaces and reduce noise
  4. Buried in blown insulation to save space

Explanation

Flexible duct must be installed fully extended and supported according to the manufacturer’s instructions. Sharp bends, compression, and unsupported spans restrict airflow, increase fan energy use, and can damage the duct. Burying it in insulation is acceptable only where the listing and installation instructions permit it, not as a way to save space.

Question 37Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

An air-conditioning coil in a house produces condensate. Which method is acceptable for disposing of it?

  1. Drain it through a trapped line to a suitable disposal point Correct answer.
  2. Discharge it directly onto the basement floor near the floor drain
  3. Connect it rigidly to the sanitary sewer with no air gap
  4. Route it into the furnace flue to evaporate

Explanation

Condensate from cooling coils must be carried away through a trapped drain to an approved disposal point. A trap prevents sewer gas or conditioned air from moving through the drain line, and an air gap or approved connection protects the potable water and sewer systems. Discharging onto the floor or into the flue can cause damage or unsafe operation.

Question 38Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A duct passes through a fire separation between an attached garage and a house. What is required at the penetration?

  1. A screen to prevent rodent entry
  2. A flexible connection to reduce vibration
  3. Nothing, because the duct is part of the house HVAC system
  4. A fire damper or an approved firestop assembly Correct answer.

Explanation

A duct that penetrates a fire separation must not reduce the separation’s fire-resistance rating. An approved fire damper or firestop assembly closes or seals the penetration so fire and smoke cannot spread through the duct opening. Flexible connectors, screens, and untreated openings do not provide the required protection.

Question 39Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Which statement about return air in a house HVAC system is correct?

  1. Return air may be drawn from a closet storing paint and solvents
  2. Return air must always be drawn from the garage to ventilate it
  3. Return air may be drawn from any bathroom if the door has an undercut
  4. Return air from a fuel-fired appliance room requires a designed combustion air supply Correct answer.

Explanation

Return air must not be drawn from a room containing a fuel-fired appliance unless that room is designed with a supply of combustion air. Removing return air can depressurize the room and cause the appliance to backdraft flue gases. Bathrooms, garages, and closets storing paints or solvents are also inappropriate because they contain moisture, vehicles, or flammable products.

Question 40Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Where a fuel-fired furnace is installed in a house, which location is generally acceptable under Part 6?

  1. In a garage with the furnace resting on the floor
  2. In a basement room with a permanent combustion air supply and code clearances Correct answer.
  3. In a bedroom closet with a solid door and no combustion air opening
  4. In a bathroom with a ceiling exhaust fan

Explanation

A fuel-fired furnace needs an adequate combustion air supply and the clearances specified for the appliance. A basement mechanical room designed with permanent combustion air and proper clearances can meet those requirements. A bedroom closet without air, a bathroom, and a garage floor location do not normally provide the required safety conditions.

Question 41Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Under the building code, a house heating system must be capable of maintaining what indoor air temperature at the outdoor design temperature?

  1. 18°C
  2. 24°C
  3. 20°C
  4. 22°C Correct answer.

Explanation

The building code requires a house heating system to be sized and installed so that it can maintain an indoor air temperature of 22°C at the outdoor design temperature. This is the benchmark used when selecting heating equipment and designing heat distribution. A system that cannot hold 22°C is considered undersized.

Question 42Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A bathroom exhaust fan in a house must discharge the exhaust air to which location?

  1. Into the attic space
  2. Into the return-air plenum
  3. To the outdoors Correct answer.
  4. Into the attached garage

Explanation

Moisture-laden bathroom air must be discharged to the outdoors so it cannot condense inside the building envelope or be redistributed through the house. Dumping exhaust into an attic, soffit or return plenum can cause mold and decay. A dedicated duct to the exterior is the normal requirement.

Question 43Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

How must an air filter in a house forced-air heating system be installed?

  1. Located downstream of the furnace
  2. Accessible for cleaning Correct answer.
  3. Bypassed during the cooling season
  4. Sealed inside the duct

Explanation

Filters collect dust and must be reached regularly without dismantling ductwork or appliances. The code requires filters to be readily accessible for cleaning or replacement. A filter buried inside a sealed duct cannot be maintained and soon becomes a restriction.

Question 44Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A supply duct runs through an unheated attic in a cold climate. How should the duct be installed?

  1. Insulated, vapour barrier on the cold side
  2. Insulated, vapour barrier on the warm side Correct answer.
  3. Insulated only
  4. Without insulation

Explanation

In winter the duct carries warm air while the attic is cold, so insulation must keep the duct surface above the dew point. The vapour barrier belongs on the warm side of the insulation to stop moisture from reaching the cold surface. Without it, condensation can saturate the insulation and damage the ceiling.

Question 45Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Where should a room thermostat for a house heating system be located?

  1. On an interior wall away from heat sources Correct answer.
  2. Inside the return-air duct
  3. On an exterior wall directly beside a window
  4. Directly above a supply register

Explanation

A thermostat controls the heating system based on the temperature it senses at its own location. If it sits near a heat source, window or supply register, it reads a false temperature and the rooms stay uncomfortable. Free air circulation around the thermostat gives representative control.

Question 46Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

How must joints in a house duct system be made?

  1. Left unsealed to relieve pressure
  2. Taped only with ordinary cloth tape
  3. Fastened and sealed against air leakage Correct answer.
  4. Sealed only at the furnace connection

Explanation

Every joint in a duct system is a potential air leak that wastes energy and can upset room pressures. Ducts must therefore be mechanically fastened and sealed so that air travels to the intended outlets. Relying on tape alone or leaving joints open does not meet this requirement.

Question 47Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

Which material is acceptable for a clothes dryer exhaust duct in a house?

  1. Aluminum foil flexible duct
  2. Smooth metal duct Correct answer.
  3. Plastic duct
  4. Vinyl flexible duct

Explanation

Dryer exhaust carries lint and hot, moist air, and lint can ignite inside the duct. Smooth metal duct has the least resistance and is easiest to clean, so it is the permitted material. Flexible vinyl or foil ducts trap lint and are not acceptable for dryer exhaust.

Question 48Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

What is the function of a backdraft damper at an exhaust fan termination?

  1. Measures the exhaust airflow rate
  2. Reduces the fan noise level
  3. Stops outdoor air entry when off Correct answer.
  4. Filters lint from the exhaust air

Explanation

A backdraft damper is a lightweight flap at the exhaust termination that opens when the fan runs. When the fan stops, gravity or spring action closes the flap so outdoor air, rain and cold cannot flow back through the duct. It is not a filter, silencer or airflow meter.

Question 49Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A house has a large kitchen exhaust fan and a natural-draft gas water heater. What is the main concern?

  1. The exhaust fan may overheat
  2. The water heater may freeze
  3. Flue gases may spill indoors Correct answer.
  4. The house may become over-pressurized

Explanation

A powerful exhaust fan removes air from the house faster than it can be replaced, lowering indoor pressure. A natural-draft appliance depends on a stable chimney draft, and negative pressure can reverse that draft so flue gases spill into the house. Makeup air or interlocking is needed to control the risk.

Question 50Heating, ventilating and air-conditioning systems: Part 6 requirements applicable to houses

A return-air duct passes through an unheated attic and has small leaks. What is the most likely result?

  1. The duct static pressure decreases
  2. Attic air enters the return air Correct answer.
  3. The filter clogs less often
  4. The heating efficiency increases

Explanation

A return duct in an attic operates at a slight negative pressure, so any leak draws attic air into the return stream. That air can carry insulation fibres, dust and moisture into the HVAC system and the occupied space. Sealing the duct prevents this cross-contamination.