Glossary
HVAC glossary
34 plain-English definitions of the heating, cooling, and efficiency terms you'll see across our Learning Center — and on any honest HVAC estimate.
- AFUE
- AHJ
- BTU
- Building / Mechanical Permit
- COP
- ccASHP
- Combi Boiler
- Condensing (High-Efficiency)
- Dual-Fuel System
- Duct Leakage
- Ductless System
- Flame Sensor
- Heat Exchanger
- HRV
- High-Limit Switch
- HSPF
- Hydronic Heating
- Manual J
- MERV
- Mini-Split
- Modulating Furnace
- Refrigerant
- Relative Humidity
- SEER2
- Short-Cycling
- Smart Thermostat
- Static Pressure
- Tankless Water Heater
- Temperature Rise
- Temperature Setback
- Ton (of Cooling)
- Two-Stage Furnace
- Variable-Speed
- Zoning
Efficiency
- AFUE
- Annual Fuel Utilization Efficiency is the percentage of fuel a furnace or boiler turns into heat for your home over a year. An 80% AFUE unit is mid-efficiency; 90%+ is high-efficiency (condensing). In Saskatoon's long heating season, higher AFUE pays back faster.
- Read: What do AFUE, SEER2, and HSPF mean? → See also: SEER2 HSPF Two-Stage Furnace
- SEER2
- Seasonal Energy Efficiency Ratio 2 measures how efficiently an air conditioner or heat pump cools over a season, using updated, more realistic test conditions than the older SEER. A higher SEER2 means lower summer running costs.
- Read: What do AFUE, SEER2, and HSPF mean? → See also: AFUE HSPF ccASHP
- HSPF
- Heating Seasonal Performance Factor measures how efficiently a heat pump heats over a season. A higher HSPF means the heat pump delivers more heat per unit of electricity — useful for comparing cold-climate models.
- Read: What do AFUE, SEER2, and HSPF mean? → See also: SEER2 COP ccASHP
- Coefficient of Performance (COP)
- COP is the ratio of heating (or cooling) output to the energy input. A heat pump with a COP of 3 delivers three units of heat for each unit of electricity, because it moves heat rather than creating it.
- Read: How do cold-climate heat pumps work in a Saskatchewan winter? → See also: HSPF ccASHP
- Temperature Setback
- A setback is reducing your heating setpoint while you sleep or are away to cut energy use. Modest setbacks genuinely save energy, but in deep cold an extreme setback means the furnace has to recover a big gap on a frigid morning — and letting a home get too cold in winter can risk pipes. A smart thermostat automates a sensible setback.
- Read: How do thermostats and smart controls work? → See also: Smart Thermostat
Sizing
- BTU
- A British Thermal Unit is the amount of energy needed to raise one pound of water by one degree Fahrenheit. HVAC equipment capacity is rated in BTUs (or BTUs per hour); correct sizing matches BTUs to your home's actual heat loss or gain.
- Read: What size furnace do I need? → See also: Manual J Short-Cycling
- Manual J Load Calculation (Manual J)
- A Manual J is a heating and cooling load calculation that determines how much heating or cooling a home actually needs, based on size, insulation, windows, air leakage, and the local design temperature. It's how equipment is right-sized instead of guessed.
- Read: What size furnace do I need? → See also: BTU Short-Cycling
- Ton (of Cooling)
- A ton of cooling equals 12,000 BTUs per hour of heat removal — a historical reference to the cooling power of a ton of ice. Central air conditioners are sized in tons, matched to a home's cooling load. Bigger isn't better: an oversized AC short-cycles and won't remove humidity properly.
- Read: What drives the cost of installing air conditioning? → See also: BTU SEER2 Manual J Short-Cycling
Components
- Short-Cycling
- Short-cycling is when a furnace or AC starts and stops in quick bursts instead of running steady cycles. It's often caused by oversizing, a clogged filter, or a faulty sensor, and it wastes energy, wears out parts, and heats or cools unevenly.
- Read: What size furnace do I need? → See also: Manual J High-Limit Switch MERV
- Heat Exchanger
- The heat exchanger is the sealed metal chamber in a furnace where combustion happens. Household air passes across its hot surface to be warmed, while combustion gases (including carbon monoxide) stay sealed inside and vent outdoors. A cracked heat exchanger is a safety hazard.
- Read: How does a gas furnace work? → See also: Flame Sensor High-Limit Switch
- Flame Sensor
- The flame sensor is a small rod that detects whether the burner flame is present. If it can't sense a flame (often because it's dirty), it shuts off the gas as a safety measure — a common reason a furnace blows cold air or won't stay lit.
- Read: Why is my furnace blowing cold air? → See also: Heat Exchanger High-Limit Switch
- High-Limit Switch
- The high-limit switch shuts the burners off if the furnace gets too hot, usually because airflow is restricted by a clogged filter or blocked vents. When it trips, the blower keeps running and you feel cool air — a sign to check airflow.
- Read: Why is my furnace blowing cold air? → See also: Flame Sensor MERV Short-Cycling
- Variable-Speed
- A variable-speed blower or compressor can run at a wide range of speeds instead of simply on or off. Running low and steady most of the time means quieter operation, more even temperatures, better humidity control, and higher efficiency — the comfort tier above single- and two-stage equipment.
- Read: Is a high-efficiency furnace worth it in Saskatchewan? → See also: Modulating Furnace Two-Stage Furnace
- Smart Thermostat
- A smart thermostat connects to Wi-Fi so you can control your heating and cooling from a phone, and it adds scheduling, learning, energy reports, and alerts. Some can respond to outdoor temperature. Compatibility with two-stage, modulating, and dual-fuel systems matters, and some models may qualify for a SaskEnergy rebate.
- Read: Are smart thermostats worth it in Saskatoon? → See also: Temperature Setback Two-Stage Furnace Dual-Fuel System
- Static Pressure
- Static pressure is the resistance the blower must push against to move air through your filter, ducts, and registers. Too high — from undersized or restricted ducts or an overly dense filter — strains the blower, reduces airflow, and can trip safety switches. Measuring it helps diagnose comfort and airflow problems.
- Read: Why do leaky ducts matter, and what is duct sealing? → See also: Duct Leakage MERV High-Limit Switch
- Duct Leakage
- Duct leakage is the heated or cooled air that escapes through gaps at duct joints, seams, and connections before reaching your rooms — often into attics, crawlspaces, or cold basements. In a long Saskatoon winter, leakage wastes real money and causes uneven temperatures; sealing and balancing the ducts fixes it.
- Read: Why do leaky ducts matter, and what is duct sealing? → See also: Static Pressure MERV
Air Quality
- MERV Rating (MERV)
- Minimum Efficiency Reporting Value rates how effectively a filter captures airborne particles — higher MERV catches finer particles. The right MERV balances air cleaning with airflow; too restrictive a filter for your system can cause the airflow problems that trip safety switches.
- Read: Why is the air in my Saskatoon home so dry in winter? → See also: HRV High-Limit Switch
- Heat Recovery Ventilator (HRV)
- An HRV exchanges stale indoor air for fresh outdoor air while transferring heat from the outgoing air to the incoming air, so you ventilate without throwing away your heat. It's valuable in airtight modern homes, especially through a long prairie winter.
- Read: Why is the air in my Saskatoon home so dry in winter? → See also: MERV Relative Humidity
- Relative Humidity
- Relative humidity is the amount of moisture in the air compared with how much it could hold at that temperature. Heating very cold winter air indoors drops relative humidity sharply, which is why Saskatoon homes feel so dry in winter.
- Read: Why is the air in my Saskatoon home so dry in winter? → See also: HRV MERV
Heating
- Two-Stage Furnace
- A two-stage furnace can run on a lower setting most of the time and a higher setting in extreme cold, rather than full blast or off. That means steadier temperatures, quieter operation, and better efficiency than a single-stage unit — useful in Saskatchewan's wide temperature swings.
- Read: What size furnace do I need? → See also: Modulating Furnace AFUE
- Modulating Furnace
- A modulating furnace adjusts its heat output across a wide range instead of just high/low, holding very steady indoor temperatures and maximizing efficiency. It's the top comfort tier, often paired with a variable-speed blower.
- Read: Is a high-efficiency furnace worth it in Saskatchewan? → See also: Two-Stage Furnace AFUE
- Hydronic Heating
- Hydronic heating circulates hot water from a boiler through radiators, baseboards, or in-floor tubing to warm a home with steady radiant heat. It's quiet and even, and common in older and custom Saskatoon homes.
- Read: How do boilers and hydronic heating work? → See also: Combi Boiler BTU
- Combi Boiler
- A combination (combi) boiler heats your home and produces domestic hot water from a single appliance, heating water on demand for your taps. It saves space and simplifies maintenance versus separate units.
- Read: How do boilers and hydronic heating work? → See also: Hydronic Heating Tankless Water Heater
- Condensing (High-Efficiency)
- A condensing furnace, boiler, or tankless water heater adds a second heat exchanger that pulls so much heat from the exhaust that water vapour condenses out of it. That's why these high-efficiency units drain a little water and vent through PVC instead of metal — and why they reach the highest AFUE ratings.
- Read: How does a gas furnace work? → See also: AFUE Combi Boiler Tankless Water Heater
Heat Pumps
- Cold-Climate Air-Source Heat Pump (ccASHP)
- A cold-climate air-source heat pump uses variable-speed compressors and improved refrigerant control to keep delivering useful heat well below freezing. In Saskatoon it's usually paired with a gas furnace as a dual-fuel system for the coldest days.
- Read: How do cold-climate heat pumps work in a Saskatchewan winter? → See also: Dual-Fuel System HSPF COP
- Dual-Fuel System
- A dual-fuel (hybrid) system combines a heat pump with a gas furnace. The heat pump handles efficient heating on mild and shoulder-season days, and the furnace automatically takes over in deep cold — the sweet spot for most Saskatoon homes.
- Read: Furnace, heat pump, or dual-fuel? → See also: ccASHP AFUE HSPF
- Ductless System
- A ductless system delivers heating and cooling through indoor heads connected to an outdoor unit by a small refrigerant line, with no ducts. It's ideal for additions, older homes, and problem rooms.
- Read: What is a ductless mini-split and how does it work? → See also: Mini-Split Zoning
- Mini-Split
- A mini-split is a ductless heat pump with one outdoor unit serving one or more indoor heads. Each head is its own zone, so you can heat or cool specific rooms independently — a popular fix for hot/cold rooms in Saskatoon homes.
- Read: What is a ductless mini-split and how does it work? → See also: Ductless System Zoning ccASHP
Cooling
- Zoning
- Zoning lets different areas of a home be heated or cooled independently, instead of one temperature everywhere. Ductless mini-splits zone naturally, and ducted systems can be zoned with dampers and multiple thermostats.
- Read: Central air vs. ductless mini-split for Saskatoon homes → See also: Mini-Split Ductless System
- Refrigerant
- Refrigerant is the special fluid that circulates in an air conditioner or heat pump, absorbing heat where it's cold and releasing it where it's warm as it changes between liquid and gas. It's what lets these systems move heat rather than create it — cooling your home in summer and, in a heat pump, heating it in winter.
- Read: How does central air conditioning work? → See also: SEER2 ccASHP Ton (of Cooling)
Water Heating
- Tankless Water Heater
- A tankless (on-demand) water heater heats water only as it flows through, giving a continuous supply and eliminating standby energy loss. In Saskatoon it must be sized for very cold incoming winter groundwater so it keeps up year-round.
- Read: How do tank and tankless water heaters work? → See also: Temperature Rise Combi Boiler
- Temperature Rise
- Temperature rise is the difference between the incoming water temperature and the desired hot-water temperature. Saskatoon's cold winter groundwater means a large required rise, which is why tankless water heaters must be carefully sized here.
- Read: How do tank and tankless water heaters work? → See also: Tankless Water Heater
Permits & Code
- Authority Having Jurisdiction (AHJ)
- The Authority Having Jurisdiction is the local government body responsible for permits, inspections, and code enforcement for your address — for example a city or municipal building department. Requirements vary between jurisdictions, so always confirm with the AHJ for your location.
- Read: Do you need a permit to replace a furnace or water heater in Saskatoon? → See also: Building / Mechanical Permit
- Building / Mechanical Permit
- A building or mechanical permit is approval from your local building department to perform regulated work — such as installing heating equipment or gas appliances — followed by an inspection that verifies the work meets current code. A licensed contractor typically handles the permit and inspection for you.
- Read: Do you need a permit to replace a furnace or water heater in Saskatoon? → See also: AHJ
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