Glossary
Plain-language definitions for the HVAC and plumbing terms you'll see on estimates and in our guides — so you can decide with confidence.
Browse the Learning CenterGlossary of terms
How to use this glossary
Use these definitions to decode estimates and compare options before you book. Each term links to a related guide in our Learning Center and the service it relates to.
AFUE (Annual Fuel Utilization Efficiency)
The percentage of fuel a furnace converts into usable heat over a season. A 96% AFUE furnace turns 96 cents of …
Define → HeatingBTU (British Thermal Unit)
A unit of heat energy. HVAC and water-heating equipment are rated in BTUs (or BTU/hour) to describe heating or …
Define → HeatingDual-fuel system
A heat pump paired with a gas furnace. The heat pump handles most of the season efficiently, and the system sw …
Define → CoolingDuctless mini-split
A zoned heating and cooling system with an outdoor unit and one or more indoor heads, requiring no ductwork. I …
Define → PlumbingGas piping
The supply lines that deliver natural gas to furnaces, water heaters, ranges, and other appliances. Proper siz …
Define → HeatingHeat pump
HVAC equipment that moves heat instead of generating it — heating a home in winter and cooling it in summer in …
Define → HeatingHSPF2 (Heating Seasonal Performance Factor 2)
The heating-mode efficiency rating for heat pumps under updated test procedures. Higher HSPF2 means more heat …
Define → CoolingManual J load calculation
The ACCA-standard calculation that sizes heating and cooling equipment to a home's actual heat loss and gain — …
Define → Indoor Air QualityMERV rating
Minimum Efficiency Reporting Value — rates how well an air filter captures particles. Higher MERV traps finer …
Define → CoolingRefrigerant
The fluid that carries heat through an AC or heat pump, cycling between liquid and gas to absorb and release h …
Define → CoolingSEER2 (Seasonal Energy Efficiency Ratio 2)
A seasonal measure of cooling efficiency for air conditioners and heat pumps under updated DOE test procedures …
Define → Savings & RebatesSmart thermostat
A connected thermostat that learns schedules and allows remote control, improving comfort and efficiency. Pair …
Define → PlumbingTankless water heater
An on-demand water heater that heats water only as you use it, providing continuous hot water and a compact fo …
Define → Indoor Air QualityTemperature inversion
A weather pattern where a warm air layer traps cold, polluted air near the valley floor — common in Salt Lake …
Define → Savings & RebatesThermWise (Enbridge Gas)
Enbridge Gas's natural-gas efficiency rebate program in Utah (formerly Dominion Energy), offering rebates on q …
Define → CoolingTonnage
A measure of an air conditioner or heat pump's cooling capacity. One ton equals 12,000 BTU/hour. Correct tonna …
Define → Savings & RebatesWattsmart (Rocky Mountain Power)
Rocky Mountain Power's energy-efficiency rebate program for Utah customers, offering cash-back incentives on q …
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