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HVAC Glossary
The HVAC terms you'll hear during an estimate or repair, explained in plain English.
- SEER2
- Seasonal Energy Efficiency Ratio 2 — the federal rating for how efficiently an AC or heat pump cools over a season. Higher SEER2 means lower electricity use for the same cooling. It replaced the older SEER metric in 2023.
- AFUE
- Annual Fuel Utilization Efficiency — the percentage of fuel a furnace converts to usable heat. A 95% AFUE furnace turns 95% of its gas into heat. Higher AFUE means lower heating bills.
- HSPF2
- Heating Seasonal Performance Factor 2 — the efficiency rating for a heat pump in heating mode. Higher HSPF2 means more heat delivered per unit of electricity.
- Heat pump
- HVAC equipment that moves heat instead of generating it, providing both heating and cooling from one system. Heat pumps are especially efficient in mild climates like the Brazos Valley.
- Ductless mini-split
- A system with an outdoor unit and one or more wall- or ceiling-mounted indoor heads that conditions a space without ductwork. Common for additions, garages, shops, and rooms the main system can't reach.
- Manual J load calculation
- The industry-standard method for sizing HVAC equipment to a home's actual heat gain and loss. Proper Manual J sizing is critical in humid climates so the system runs long enough to remove moisture.
- MERV rating
- Minimum Efficiency Reporting Value — a scale (1–16 for residential) of how well an air filter captures particles. Higher MERV captures finer particles; MERV 11–13 media filters balance filtration and airflow for most homes.
- Tonnage
- A measure of an air conditioner's cooling capacity. One ton equals 12,000 BTU/hour of cooling. Sizing should come from a load calculation, not a rule of thumb — an oversized system cools too fast to dehumidify.
- Refrigerant (R-410A / R-32 / R-22)
- The fluid that absorbs and releases heat as it cycles through your system. Modern systems use R-410A or newer R-32; older systems use R-22, which is phased out and costly — a factor when deciding whether to repair or replace.
- Variable-speed
- Equipment (compressors or blowers) that adjusts output instead of simply turning fully on or off. Variable-speed systems run longer at lower output, improving comfort, efficiency, and humidity control.
- Dehumidification
- Removing moisture from indoor air. In the Brazos Valley, dehumidification is a major part of comfort — air at a lower humidity feels cooler and discourages mold and dust mites.
- Preventive maintenance (tune-up)
- A scheduled inspection and service visit — checking refrigerant, cleaning coils, testing electrical components, and replacing filters — that extends equipment life, protects warranties, and catches problems before they become breakdowns.