Glossary
HVAC Technician Terms & Vocabulary
15 essential HVAC technician terms with plain-English definitions: the vocabulary you’ll hear in training and on day one.
Key HVAC technician vocabulary
These 15 terms come up constantly in HVAC technician training, on the job and in interviews. Knowing them helps you follow instructions, document accurately and sound prepared.
- BTU
- British thermal unit: the amount of heat needed to raise one pound of water by 1°F.
- Capacitor
- An electrical component that helps start and run motors and compressors.
- Compressor
- The pump that raises refrigerant pressure and circulates it.
- Condenser
- The outdoor coil where refrigerant releases heat.
- Evaporator coil
- The indoor coil where refrigerant absorbs heat from the air.
- Heat pump
- A system that moves heat into a building in winter and out in summer.
- Metering device (TXV)
- A thermostatic expansion valve that controls refrigerant flow into the evaporator.
- Micron gauge
- A tool that measures deep vacuum to confirm a system is dry and leak-free.
- Recovery
- Removing refrigerant from a system into a cylinder, as required by EPA rules.
- Refrigeration cycle
- The process of compression, condensation, expansion and evaporation that moves heat.
- SEER2
- Seasonal Energy Efficiency Ratio, updated test procedure: a cooling efficiency rating.
- Static pressure
- Air pressure in ductwork, used to evaluate airflow problems.
- Subcooling
- The temperature of liquid refrigerant below its condensing point, used to check charge.
- Superheat
- The temperature of refrigerant vapor above its boiling point, used to check charge.
- Ton (cooling)
- 12,000 BTU per hour of cooling capacity.
Practice these terms
Test yourself with the free HVAC Technician practice test: it includes vocabulary questions built from this list. For a complete course, see HVAC Technician training.
Browse terms from every career in our career glossary.