Glossary
HVAC Terms, in Plain English
A homeowner-friendly glossary for air conditioning, heating, heat pumps, and the comfort decisions that matter on the Northshore.
A
- AHJ
- Authority Having Jurisdiction — the local government office, such as a parish or municipal building department, that interprets and enforces permit and code requirements. Specific rules vary by jurisdiction, so confirm details with your local building department.
- Air handler
- The indoor cabinet that moves conditioned air through the home.
B
- Blower motor
- The motor that pushes air through the duct system.
C
- Capacitor
- An electrical component that helps certain HVAC motors start and run.
- Compressor
- The outdoor component that pressurizes refrigerant so heat can move.
- Condensate drain
- The drain line that removes water collected during dehumidification.
- Condenser coil
- The outdoor coil that releases heat from the refrigerant.
D
- Delta T
- The temperature difference between return air and supply air.
- Duct leakage
- Air lost through gaps, cracks, or disconnected duct joints.
E
- Emergency heat
- Backup heat used by some heat-pump systems when normal heat-pump operation cannot keep up.
- EPA Universal Refrigerant Certification
- Certification for technicians who work with refrigerants across equipment types.
- Evaporator coil
- The indoor coil that absorbs heat and moisture from the air.
H
- Heat exchanger
- The furnace component that transfers combustion heat without mixing exhaust with household air.
- Heat pump
- A system that moves heat for both cooling and heating.
- HSPF2
- Heating Seasonal Performance Factor 2, a heat-pump efficiency rating.
L
- Load calculation
- A sizing process that estimates how much heating and cooling a home needs.
M
- Manual J
- The residential load-calculation method commonly used for HVAC sizing.
- MERV
- Minimum Efficiency Reporting Value; a filter-efficiency scale.
R
- Refrigerant
- The fluid that carries heat through an AC or heat-pump system.
- Reversing valve
- A heat-pump part that changes refrigerant direction for heating or cooling.
S
- SEER2
- Seasonal Energy Efficiency Ratio 2, a cooling-efficiency rating.
- Short cycling
- Frequent starts and stops that reduce comfort and equipment life.
- Static pressure
- Resistance to airflow in ducts and equipment.
T
- Thermostat calibration
- Checking that the thermostat reads and controls temperature accurately.
- TXV
- Thermal expansion valve; a metering device that controls refrigerant flow.
V
- Variable-speed
- Equipment that can run at multiple speeds for steadier comfort and better humidity control.
Keep going
From definitions to decisions.
Pair these terms with the Learning Center to compare repair, replacement, and maintenance with confidence — then reach the owner directly when you are ready.