Glossary
HVAC & Ontario rebate terms, in plain English.
A quick reference for the heating, cooling, efficiency, and incentive terms you'll meet while choosing a new system for your GTA home.
A
- AFUE (Annual Fuel Utilization Efficiency)
- The percentage of a furnace's fuel that becomes usable heat over a year. A 96% AFUE furnace turns 96% of its gas into home heat; the rest is lost to exhaust. Higher AFUE means lower gas bills.
- AHRI Certified
- A rating verified by the Air-Conditioning, Heating, and Refrigeration Institute confirming that a specific matched system (e.g., an outdoor unit paired with a particular indoor coil) actually delivers its published efficiency. Rebates and warranties often require an AHRI-certified match.
- Auxiliary (backup) heat
- The secondary heat source that supplements a heat pump when it's colder than the heat pump's balance point. In a GTA hybrid system this is usually the gas furnace; in all-electric setups it's electric resistance heat.
B
- Balance point
- The outdoor temperature at which a heat pump's heat output exactly matches the home's heat loss. Above it the heat pump keeps up on its own; below it, backup heat takes over. Setting it correctly is part of a proper install.
- BAS (Building Automation System)
- A centralized control system that monitors and manages a commercial building's HVAC, ventilation, and sometimes lighting. It improves efficiency and comfort and lets managers schedule and troubleshoot equipment across zones or sites.
- BTU (British Thermal Unit)
- A unit of heat energy. Furnace heating capacity is rated in BTUs per hour; air conditioner and heat pump capacity is often expressed in tons, where one ton equals 12,000 BTU/hour of cooling.
C
- Cold-climate heat pump (CCHP)
- A heat pump engineered with inverter compressors and enhanced refrigerant circuits to keep heating efficiently in deep cold, with many models rated to deliver useful heat down to roughly -25°C or lower — suitable for Ontario winters.
- Condensing furnace
- A high-efficiency (90%+ AFUE) furnace that extracts extra heat by condensing exhaust water vapour. It vents through plastic pipe rather than a metal chimney and produces a condensate drain.
- COP (Coefficient of Performance)
- A heat pump's heat output divided by the electricity it consumes. A COP of 3 means three units of heat per unit of electricity — the reason heat pumps can heat so efficiently compared to electric resistance heat.
D
- DOAS (Dedicated Outdoor Air System)
- A commercial system that conditions and delivers fresh outdoor air separately from the equipment handling heating and cooling. It ensures reliable ventilation and humidity control in spaces with strict air-quality needs, such as restaurants and medical offices.
- Dual-fuel / hybrid heating
- A system pairing a heat pump with a gas furnace on shared ductwork. Controls run the efficient heat pump for most of the season and switch to the furnace on the coldest nights — the realistic GTA setup.
- Ductless mini-split
- A heat pump with one or more wall- or ceiling-mounted indoor heads connected to an outdoor unit by refrigerant lines, with no ductwork. Ideal for additions, ADUs, or rooms that are hard to heat or cool.
- Ductless multi-zone
- A ductless heat pump with several indoor heads connected to one outdoor unit, each head controlling its own room. Ideal for conditioning multiple problem spaces — bedrooms, a bonus room, an addition — without adding ductwork.
E
- ECM (Electronically Commutated Motor)
- A high-efficiency, variable-speed blower motor found in modern furnaces and air handlers. It uses less electricity than older PSC motors and enables quieter, more even airflow.
- ERV (Energy Recovery Ventilator)
- A ventilation device that exchanges stale indoor air for fresh outdoor air while recovering both heat and some humidity. Similar to an HRV but also moderates moisture transfer — useful in some Ontario homes.
G
- Geothermal heat pump
- A heat pump that exchanges heat with the ground (or groundwater) instead of outdoor air, using buried loops. Very efficient and long-lasting, with a higher install cost; eligible for the largest Ontario rebate tier.
H
- Heat pump water heater (hybrid)
- A water heater that uses heat-pump technology to move heat from the surrounding air into the tank, making it far more efficient than a standard electric tank. A higher-efficiency option where electrification and rebates are a priority.
- HRS (Home Renovation Savings Program)
- Ontario's active home-efficiency rebate program, running through 2026. Offers up to $7,500 for a qualifying cold-climate heat pump and up to $12,000 for geothermal, with per-home caps based on current heating type.
- HRV (Heat Recovery Ventilator)
- A ventilation device that swaps stale indoor air for fresh outdoor air while capturing most of the heat from the outgoing air — bringing in fresh air without throwing away the heat you paid for. Ideal for tight, modern homes.
- HSPF2 (Heating Seasonal Performance Factor 2)
- The current standard rating for a heat pump's heating-season efficiency. Higher HSPF2 means more heat delivered per unit of electricity. The '2' reflects updated, more realistic test conditions.
L
- Light commercial HVAC
- Heating and cooling for smaller commercial spaces — offices, retail, small clinics — typically using packaged rooftop units or split systems rather than large central plants. The bridge between residential equipment and full commercial mechanical systems.
- Load calculation (Manual J)
- The industry-standard method for sizing heating and cooling equipment. It models a home's actual heat loss and gain from insulation, windows, air leakage, and layout — not square footage alone — to find the right capacity.
M
- Make-up air (MUA)
- Tempered fresh air mechanically supplied to replace air removed by exhaust systems, most critically in commercial kitchens. Without balanced make-up air a building goes negative-pressure, hoods underperform, and doors become hard to open.
- Manufacturer warranty (parts vs. labour)
- Equipment warranties usually cover replacement parts for a set period when registered, but the labour to install those parts is often separate and may be covered by the installer or a maintenance plan. Always confirm what is and isn't covered before buying.
- MERV (Minimum Efficiency Reporting Value)
- A 1–16 scale rating how well an air filter captures particles — higher MERV traps finer dust, pollen, and allergens. The filter must be matched to the system so it cleans the air without choking airflow.
- Modulating furnace
- A furnace that continuously adjusts its flame and blower across a wide range rather than running full-on or off. It holds steadier temperatures, runs quietly, and is the most efficient (and priciest) staging option.
P
- Packaged rooftop unit (RTU)
- A self-contained HVAC unit installed on a commercial roof that houses heating, cooling, and ventilation in one cabinet. Common for offices, retail, and restaurants because it saves indoor space and is serviced from the roof.
R
- R-22 (refrigerant)
- An older refrigerant phased out for environmental reasons. Systems still using R-22 are increasingly costly to service, which is a common signal that an aging air conditioner is due for replacement.
- R-410A / R-454B (refrigerants)
- Modern refrigerants used in current air conditioners and heat pumps, replacing the phased-out R-22. R-454B is a newer, lower-global-warming-potential refrigerant being adopted across the industry.
S
- SEER2 (Seasonal Energy Efficiency Ratio 2)
- The current standard rating for an air conditioner or heat pump's cooling-season efficiency. Higher SEER2 means lower electricity use for the same cooling. The '2' reflects updated, more realistic test conditions.
T
- Tankless (on-demand) water heater
- A water heater that heats water only as it flows, using a high-BTU burner, instead of storing it in a tank. Delivers endless hot water and lasts longer, but costs more upfront and needs periodic descaling in hard water.
- Ton (of cooling)
- A unit of cooling/heat-pump capacity equal to 12,000 BTU/hour. A typical GTA home needs a few tons of cooling; the exact figure should come from a load calculation, not square footage.
- Trane Comfort Specialist
- Trane's recognition for dealers who meet high standards for technician training, customer satisfaction, and business practices. Energy Clean holds this designation. It reflects ongoing training on Trane equipment, not a guarantee that Trane suits every home.
- TSSA (Technical Standards & Safety Authority)
- The Ontario body that regulates fuel safety, including natural-gas appliances. Gas furnace, boiler, and water-heater work must meet TSSA codes and be performed by licensed technicians.
- Two-stage furnace
- A furnace with high and low heat outputs. It runs on the gentler low stage most of the time for quieter, more even heat, stepping up to high only in deep cold — more efficient and comfortable than single-stage.
V
- Variable-speed (inverter)
- Compressor or motor technology that ramps smoothly across a range of speeds instead of switching fully on/off. It's central to how cold-climate heat pumps stay efficient and to even, quiet comfort.
- VRF / VRV (Variable Refrigerant Flow)
- An advanced commercial heat-pump system that runs refrigerant to multiple indoor units and varies flow to each, even heating some zones while cooling others. Efficient and flexible for offices, multi-unit residential, and mixed-use buildings.
Z
- Zoning (HVAC zoning)
- Dividing a home or building into independently controlled areas using motorized dampers in the ductwork and a thermostat per zone. It evens out multi-level homes by sending conditioned air only where it's needed, rather than relying on one thermostat.
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