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HVAC Glossary

HVAC Glossary, 35 Terms Explained Plainly

Plain-English definitions of HVAC terms, certifications, refrigerants and rebate programs Halton homeowners encounter when getting quotes. Written by IKAD Mechanical, family-owned HVAC contractor in Oakville since 2010.

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Furnaces & Heating

AFUE (Annual Fuel Utilization Efficiency)
The percentage of gas energy a furnace converts to usable heat over a typical heating season. A 95% AFUE furnace turns 95 cents of every dollar of natural gas into actual home heat. Today's high-efficiency tier in Halton is 95% to 98% AFUE.
BTU (British Thermal Unit)
A unit of heat energy. One BTU is the energy needed to raise one pound of water by 1°F. Typical Halton homes need 60,000 to 90,000 BTU per hour of heating capacity. Furnaces and AC equipment are rated in BTU/hr.
Condensing furnace (Condensing furnace)
A high-efficiency furnace (90% AFUE and higher) that extracts additional heat from combustion gases by condensing the water vapour in them. Requires PVC venting and a condensate drain. Standard for all new gas furnace installations in Ontario.
Heat exchanger (Heat exchanger)
The component of a furnace that transfers heat from combustion gases to the air being circulated through the home. A cracked heat exchanger is a carbon-monoxide risk and is not repairable — the furnace must be replaced.
Inducer motor (Inducer motor)
The small motor on a high-efficiency furnace that pulls combustion gases through the heat exchanger and out the vent. A common failure on 12+ year old furnaces. Replacement: typically $350 to $650 installed.
Modulating (Modulating furnace or boiler)
Equipment that can run at variable output (often 35% to 100% of capacity) rather than just on/off. Modulating furnaces run longer cycles at lower fire, which is quieter, more efficient and more comfortable than single-stage equipment.
PVC vent (PVC venting)
The white plastic exhaust and intake piping on a high-efficiency furnace. Replaces the metal B-vent used on older mid-efficiency equipment. The two pipes emerging from the side of newer Halton homes belong to the furnace.

Air Conditioning & Cooling

SEER (Seasonal Energy Efficiency Ratio)
Cooling efficiency for central AC and heat pumps over a season. Higher SEER means lower electricity per ton of cooling. Replaced in 2023 by SEER2 (a stricter measurement standard).
SEER2 (Seasonal Energy Efficiency Ratio (2023+ standard))
The current Canadian and US efficiency standard for residential cooling equipment, measured under more realistic conditions than the previous SEER. Ontario minimum is 14 SEER2. Premium variable-speed equipment reaches 22 SEER2.
Tonnage (Tonnage (AC and heat pump))
AC and heat pump capacity unit. 1 ton equals 12,000 BTU per hour of cooling. Typical Halton home needs 2 to 4 tons. Oversizing is the most common installation mistake — short-cycles in humid weather and never pulls moisture out.

Heat Pumps

Cold-climate heat pump (Cold-climate air-source heat pump (ccASHP))
A heat pump designed for sub-zero operation. Models include Mitsubishi Hyper-Heat, Daikin Aurora, Lennox SL25XPV. Holds rated capacity to -15°C and continues producing heat (at reduced efficiency) to -25°C. Eligible for up to $7,500 under the Ontario Home Renovation Savings Program.
COP (Coefficient of Performance)
Heat pump efficiency ratio. A COP of 3.0 means 3 units of heat output per 1 unit of electrical input. Modern cold-climate heat pumps average COP 2.5 to 3.5 in Halton winter conditions.
HSPF (Heating Seasonal Performance Factor)
Heat pump heating efficiency over a season. Higher HSPF means lower electricity per BTU of heat. Modern cold-climate heat pumps achieve HSPF 11 to 13 (region-dependent).
Hybrid system (Hybrid heat pump and furnace system)
An HVAC configuration that pairs a cold-climate heat pump (primary) with a gas furnace (backup) on a single control. The heat pump handles 80% of heating hours; the furnace handles peak-cold backup below -15°C. The most cost-effective heating approach in Halton.

Ductless Mini-Splits

Ductless mini-split (Ductless mini-split system)
A heat pump or AC system without ductwork: an outdoor compressor connects to one or more wall-mounted or ceiling-cassette indoor heads via refrigerant lines. Ideal for heritage homes without ducts, problem rooms, or additions.

Ductwork & Airflow

Aeroseal (Aeroseal duct sealing)
A patented process that seals leaky ducts from the inside by pressurizing the duct system and injecting an aerosolized polymer that bridges leaks as it passes through. Best for ducts buried in walls or ceilings where manual mastic sealing is impractical.
Static pressure (Total external static pressure)
Resistance to airflow in a duct system, measured in inches of water column. Manufacturer spec is 0.5 inches. Most Halton homes test at 0.9 to 1.2 inches, which means the blower is fighting the duct system. High static pressure shortens equipment life and starves distant rooms.

Air Balancing

CFM (Cubic Feet per Minute)
Unit of airflow. A typical bedroom needs 60 to 100 CFM of supply air, depending on size and heat load. Air balancing measures CFM at every register to confirm each room gets its designed airflow.

Refrigerants

R-22 (R-22 refrigerant (HCFC-22, Freon))
An ozone-depleting refrigerant phased out for new equipment in Canada. Illegal to import or manufacture since 2020. R-22 systems still in operation can be serviced with recovered stock, but the right move on R-22 equipment is planned replacement before the next major repair.
R-410A (R-410A refrigerant (Puron))
The dominant residential AC and heat pump refrigerant from approximately 2010 to 2024. Being phased down under new Canadian regulations starting 2025. New equipment now uses R-454B.
R-454B (R-454B refrigerant (Opteon XL41, Solstice 454B))
The low-global-warming-potential refrigerant replacing R-410A in new Canadian residential AC and heat pump equipment from January 2025. Mildly flammable (A2L safety class), which changes brazing, leak-detection and line-set requirements. Manufacturer-certified installers required.

Ventilation

HRV (Heat Recovery Ventilator)
A balanced ventilation device that brings fresh outdoor air into the home while recovering 70% to 80% of the heat from the air being exhausted. Required by Ontario code in tight modern homes. Brands installed: Lifebreath, Venmar, vanEE.

In-Floor & Hydronics

PEX (Cross-linked polyethylene tubing)
Flexible plastic tubing used for hydronic in-floor heating, snow melt and plumbing supply lines. Service life is 50+ years embedded in concrete. Brands: Uponor, Watts.

Commercial HVAC

MUA (Make-Up Air unit)
A commercial HVAC unit that delivers fresh outdoor air, usually heated, to replace air exhausted by kitchen hoods or industrial ventilation. Required for commercial kitchens to maintain pressure balance.
NFPA 96 (NFPA 96 (Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations))
The North American code standard for commercial kitchen hood systems: 250–350 FPM capture velocity, welded duct construction, 18-inch clearance to combustibles, accessible cleanout doors every 12 feet, balanced make-up air within 90% of exhaust CFM.

Filtration & Air Quality

MERV (Minimum Efficiency Reporting Value)
Air filter rating from MERV 1 (low) to MERV 16 (HEPA-equivalent). MERV 8 to 11 is the sweet spot for most Halton homes. MERV 13+ may overload some older furnace blowers and increase static pressure.

Rebates & Programs

Greener Homes Loan (Canada Greener Homes Loan)
An interest-free federal loan program up to $40,000 (10-year repayment) for residential energy retrofits including heat pumps, insulation, windows, solar PV and heat pump water heaters. Requires a pre-retrofit Energy Advisor audit. The Greener Homes Grant closed in 2024; only the Loan remains active.
HRS (Home Renovation Savings Program)
Ontario's primary residential HVAC rebate program, launched January 28, 2025, replacing the Enbridge HER+ program. Offers up to $7,500 for an air-source heat pump, $12,000 for ground-source, $1,000 for a heat pump water heater. Registration deadline May 31, 2026. No pre-retrofit energy audit required.

Licensing & Credentials

ECRA (Electrical Contractor Registration Agency)
The Ontario authority that licenses electrical contractors. IKAD Mechanical is ECRA / ESA licensed, required for any electrical work on HVAC equipment.
ESA (Electrical Safety Authority)
The Ontario regulator for electrical safety. ESA inspects electrical work and issues permits. Works alongside ECRA on contractor licensing.
HRAI (Heating, Refrigeration and Air Conditioning Institute of Canada)
The national trade association for HVAC contractors and manufacturers in Canada. HRAI member contractors meet professional standards and complete ongoing training.
TSSA (Technical Standards and Safety Authority)
Ontario's regulator for gas appliances and piping. Issues G1, G2 and G3 gas-fitting certifications. G3 covers residential work, G2 commercial. All natural gas work in Ontario must be performed by a TSSA-certified contractor.
WSIB (Workplace Safety and Insurance Board)
Ontario's workers' compensation authority. WSIB coverage is mandatory for HVAC contractors with employees. Always verify your contractor's WSIB clearance before they start work on your property.

HVAC Design

Manual J (ACCA Manual J load calculation)
The industry-standard method for calculating heating and cooling load room-by-room for a residential building. Accounts for insulation, window count, orientation, air infiltration and equipment efficiency. The right way to size HVAC equipment, IKAD performs Manual J on every install.
Zoning (HVAC zoning)
Splitting a forced-air or hydronic system into multiple independently-controlled zones (e.g. upstairs/downstairs, master bedroom, basement). Each zone has its own thermostat and damper or zone valve. Typical Halton retrofit cost: $2,200 to $6,500 for 2 to 3 zones.

Looking for the full FAQ? See our 49-question FAQ page covering pricing, hiring, equipment lifespan, troubleshooting, rebates and indoor air quality.

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