HVAC glossary, in plain English.
The terms you'll hear on a service call or read on a quote — defined honestly, with no jargon and no sales spin, by the Greater Air & Heating team.
AFUE (Annual Fuel Utilization Efficiency)
The efficiency rating for furnaces: the percentage of fuel that becomes usable heat over a season. A 90% AFUE furnace turns 90 cents of every fuel dollar into heat.
Heating services →Air Handler
The indoor unit that moves conditioned air through your ductwork. It houses the blower and, in most systems, the evaporator coil.
BTU (British Thermal Unit)
The basic unit of heating and cooling energy. Air conditioner capacity is measured in BTUs per hour; 12,000 BTU/h equals one ton of cooling.
Compressor
The heart of an air conditioner or heat pump — the outdoor component that pumps refrigerant through the system. It is usually the most expensive single part, which is why warranties and maintenance matter.
Repair or replace? →Condensate Drain
The line that carries away the moisture your AC pulls from the air. In humid Louisiana summers a clogged condensate drain is one of the most common causes of water damage and system shutdowns.
Condenser
The outdoor unit of a split system. It releases the heat collected from inside your home to the outside air.
Ductless Mini-Split
A heating and cooling system with an outdoor unit and one or more wall-mounted indoor heads, requiring no ductwork. Ideal for additions, garages, shops, sunrooms, and rooms the existing ducts never reached.
Mini-split systems →Evaporator Coil
The indoor coil where refrigerant absorbs heat and moisture from your home's air. A dirty or frozen evaporator coil is a frequent cause of weak cooling.
Heat Exchanger
The furnace component that transfers heat from combustion to your air while keeping exhaust gases separate. A cracked heat exchanger is a safety issue — one reason annual heating inspections matter.
Heating services →Heat Pump
A system that both cools and heats by moving heat rather than generating it — cooling like an AC in summer and running in reverse in winter. Well suited to Louisiana's mild-to-moderate winters.
HSPF2 (Heating Seasonal Performance Factor)
The seasonal heating-efficiency rating for heat pumps under the current federal test procedure. Higher HSPF2 means lower winter operating cost.
HVAC
Heating, Ventilation, and Air Conditioning — the whole system of equipment, controls, and ductwork that keeps your home comfortable and the air healthy.
IAQ (Indoor Air Quality)
How clean and healthy the air inside your home is — affected by filtration, humidity, ventilation, and duct condition. Poor IAQ shows up as dust, allergies, and musty odors.
Indoor air quality services →Latent vs. Sensible Cooling
Sensible cooling lowers the temperature; latent cooling removes moisture. In Central Louisiana the latent job is enormous — a system that only cools without dehumidifying leaves the house cold and clammy.
Why humidity control matters →Load Calculation (Manual J)
The industry-standard calculation (ACCA Manual J) of how much heating and cooling your specific home needs, based on size, insulation, windows, orientation, and air leakage. The foundation of correct system sizing — never a square-footage guess.
How AC sizing works →MERV Rating
Minimum Efficiency Reporting Value — how effectively an air filter captures particles. Higher MERV filters catch more, but must be matched to your system's airflow capability.
Refrigerant
The working fluid that carries heat out of your home. Refrigerant types are periodically phased out by federal regulation, which can make servicing older systems progressively more expensive.
Return Air
The air pulled back into the system to be conditioned again. Undersized or leaky returns choke airflow and are a common hidden cause of comfort problems.
SEER2 (Seasonal Energy Efficiency Ratio)
The seasonal cooling-efficiency rating under the current federal test procedure. A higher SEER2 system uses less electricity for the same cooling — the main driver of summer operating cost.
Short-Cycling
When a system turns on and off in rapid, short runs — usually a symptom of oversizing or a fault. It wears equipment early, wastes energy, and skips the humidity-removal work our climate demands.
How AC sizing works →Static Pressure
The resistance your blower pushes against in the duct system — HVAC blood pressure. High static pressure from undersized or kinked ducts strains equipment and starves rooms of airflow.
Ductwork services →Ton (of Cooling)
A unit of air-conditioning capacity equal to 12,000 BTU per hour. Residential systems typically range from 1.5 to 5 tons — but the right tonnage comes from a load calculation, not the size of the old unit.
Zoning
Dividing a home into independently controlled comfort areas, each with its own thermostat — the fix for the eternal upstairs-vs-downstairs battle.
Why one room is always hot →Still have a question?
Start with the Learning Center guides, browse frequently asked questions, or ask us directly — straight answers are the whole point.
Ready for comfort you can count on?
Request service or call now for emergency help. Our team is standing by across Central Louisiana.