Glossary
HVAC & Plumbing Glossary
Industry terms explained in plain English.
This glossary supports the Learn and Compare paths. Use it when a quote includes abbreviations, rating systems, equipment terms, or permit language that is hard to judge without context.
- AFUE
- Annual Fuel Utilization Efficiency. A furnace efficiency rating showing how much fuel becomes usable heat.
- BTU
- British Thermal Unit. A measure of heating or cooling capacity used when sizing HVAC and water-heating equipment.
- Ductless Mini-Split
- A heat-pump system with an outdoor unit and one or more indoor heads, used when ducts are absent or zoning is needed.
- Heat Pump
- An HVAC system that moves heat instead of creating it directly, providing efficient heating and cooling from one system.
- Heat Pump Water Heater
- A water heater that uses heat-pump technology to move heat from surrounding air into the water tank.
- HSPF2
- A modern seasonal heating-efficiency rating for heat pumps. Higher numbers generally indicate better heating efficiency.
- Load Calculation
- A sizing process, often called Manual J, used to estimate the heating and cooling load of a home.
- Manual J
- A residential HVAC load calculation method that accounts for home size, insulation, windows, orientation, air leakage, and climate.
- MERV
- Minimum Efficiency Reporting Value. A filter rating that describes how effectively a filter captures airborne particles.
- Refrigerant
- The fluid inside heat pumps and air conditioners that absorbs and releases heat as it changes pressure and temperature.
- SEER2
- A current seasonal cooling-efficiency rating for air conditioners and heat pumps. Higher numbers generally mean less electricity for cooling.
- Static Pressure
- Resistance to airflow inside ducts. High static pressure can reduce comfort, efficiency, and equipment life.
- Tankless Water Heater
- An on-demand water heater that heats water as it flows through the unit instead of storing hot water in a tank.
- Tempering Valve
- A mixing valve that blends hot and cold water to reduce scald risk at fixtures.
- UFER Ground
- A concrete-encased grounding electrode sometimes referenced during electrical or mechanical work that involves grounding review.