Ontario HVAC and Home Energy Glossary

Plain-language definitions for the 50 HVAC, home energy, Ontario regulation, and consumer protection terms used across our guides. Every entry links to its dedicated page with a longer definition, related guides, and authoritative sources.

Click any term to read the full definition. Looking for a buyer-guide explainer instead? Browse our guides library or pick a topic pillar.

Metrics and Efficiency Ratings

• ACH50 - Air Changes per Hour at 50 Pascals. The blower door test result expressed as how many times the home's air volume turns
• AFUE - Annual Fuel Utilization Efficiency. The percentage of fuel a furnace converts to usable heat over a heating season. Mode
• BTU - British Thermal Unit. The amount of heat needed to raise one pound of water by one degree Fahrenheit. HVAC equipment is
• Blower Door Test - A diagnostic test that measures a home's air leakage by depressurizing it with a calibrated fan in an exterior door. Res
• CFM - Cubic Feet per Minute. The standard volumetric airflow measurement for HVAC equipment, range hoods, bath fans, and HRV/E
• COP - Coefficient of Performance. The instantaneous ratio of useful heat moved to electricity consumed by a heat pump. A COP o
• HSPF2 - Heating Seasonal Performance Factor 2. The 2023+ heating-mode efficiency rating for heat pumps in BTU per watt-hour, rep
• Manual D - ACCA Manual D: the duct-sizing methodology paired with Manual J. Determines duct dimensions and static pressure to deliv
• Manual J - ACCA Manual J: the industry-standard residential heating and cooling load calculation. Required by code for sizing HVAC
• Manual S - ACCA Manual S: equipment selection methodology that translates Manual J loads into specific make/model selections at sit
• SEER2 - Seasonal Energy Efficiency Ratio 2. The 2023+ standard for rating central AC and heat pump cooling efficiency, replacing
• Static Pressure - The resistance to airflow inside a duct system, measured in inches of water column. High static pressure means restricte
• UEF - Uniform Energy Factor. The 2017+ water heater efficiency rating that replaced EF, accounting for standby losses and reco

Equipment and Systems

• C-Wire - Common wire. The 24V power conductor required by most smart thermostats. Older Ontario homes often lack one, requiring a
• Cold-Climate Heat Pump - An air-source heat pump rated to deliver useful heat at sub-freezing outdoor temperatures, typically maintaining 70%+ of
• Ductless Mini-Split - A heat pump system with no ductwork: an outdoor compressor connected by refrigerant lines to one or more wall-mounted in
• ERV - Energy Recovery Ventilator. Like an HRV but also transfers humidity between air streams. Better for tightly-built homes
• Geothermal Heat Pump - A heat pump that exchanges heat with the earth via buried loops rather than outdoor air. Higher efficiency, much higher
• HPWH - Heat Pump Water Heater. Uses a small heat pump to move heat from surrounding air into the tank, achieving COP 2.5 to 4.0
• HRV - Heat Recovery Ventilator. A balanced ventilation device that exchanges stale indoor air for fresh outdoor air while tran
• ICF - Insulated Concrete Form. A wall-construction method using stay-in-place foam blocks filled with concrete, delivering R-2
• Make-Up Air Unit - A dedicated tempered air supply that balances large exhaust loads (range hoods, dryer vents, gas fireplace) in tight hom
• TXV - Thermostatic Expansion Valve. The metering device that controls refrigerant flow into the evaporator, replacing fixed or
• Tankless Water Heater - A water heater that heats water on demand through a heat exchanger instead of storing hot water in a tank. Continuous fl

Regulations and Authorities

• Bill 200 - Ontario's Homeowner Protection Act, 2024. Made consumer-goods NOSIs retroactively expired as of June 6, 2024, and prohib
• Global Adjustment - A line item on Ontario electricity bills that recovers the difference between contracted generator payments and the whol
• IESO - Independent Electricity System Operator. The provincial agency that operates Ontario's electricity grid and administers
• NOSI - Notice of Security Interest. A notice registered against title indicating a security interest in a fixture (e.g. rented
• OEB - Ontario Energy Board. The provincial regulator that approves electricity and natural gas distribution rates and oversees
• PPSA - Personal Property Security Act. Ontario law governing security interests in personal property. A PPSA registration again
• TSSA - Technical Standards and Safety Authority. Ontario's regulator for fuels safety (gas appliances, propane, fuel oil) and s
• Time-of-Use Pricing - Ontario electricity pricing structure with on-peak, mid-peak, and off-peak rates that vary by time of day and season. Th

Codes and Standards

• CSA B149.1 - CSA B149.1: the Canadian Natural Gas and Propane Installation Code. Governs every gas appliance installation in Ontario.
• Ontario Building Code - Ontario Building Code: the provincial regulation governing construction, renovation, and HVAC installation standards. Se

Rebate Programs

• Canada Greener Homes - Federal program offering interest-free loans up to $40,000 over 10 years for qualifying home retrofits. The grant arm cl
• HRS - Home Renovation Savings: the current Save on Energy rebate program covering insulation, sealing, windows, heat pumps, HP
• Save on Energy - Save on Energy: the Independent Electricity System Operator's (IESO) Ontario residential energy efficiency rebate progra

Financing and Contract Terms

• Amortization - The schedule by which a loan or rental obligation is paid down over time. HVAC rental contracts typically amortize over
• ECA - Equipment Control Agreement. A common Ontario rental-contract clause that grants the rental company control over the equ
• Payment Escalation - An annual percentage increase built into a long-term contract. HVAC rental contracts often include 3-7% annual escalatio
• Rental Buyout - The lump-sum amount required to terminate a rental contract and own the equipment outright. Often quoted on demand and c
• TAP - Total Amount Payable. The sum of all payments due over the full term of an HVAC rental or finance contract, including in

Safety

• Back-Drafting - When negative house pressure pulls combustion gases (including CO) back down a chimney into the living space instead of
• CO Alarm - Carbon monoxide alarm. Required by Ontario Building Code 9.32.3 outside every sleeping area in any home with a fuel-burn
• Radon - Radioactive gas from soil that accumulates in basements. Health Canada classifies it as the leading cause of lung cancer

Brands and Manufacturers

• Carrier - Carrier: a major US HVAC manufacturer. Carrier Infinity Greenspeed is their cold-climate heat pump line; Performance and
• Daikin - Daikin: world's largest HVAC OEM by revenue. Aurora is their cold-climate ductless line; Fit and One+ are their centrall
• Lennox - Lennox: US HVAC manufacturer known for the SLP99V variable-capacity furnace and the SL25XPV heat pump. Premium pricing,
• Mitsubishi Electric - Mitsubishi Electric: Japanese OEM dominant in cold-climate ductless mini-splits. Hyper Heat (H2i) is their cold-climate
• Trane - Trane: US HVAC manufacturer. XV20i is their premium variable-speed AC; XV80 is the entry condensing furnace. Owned by Tr