HVAC Glossary: 30 Terms Metro Atlanta Homeowners Actually Need to Know

The 30 terms (in plain English)

If you've ever read an HVAC estimate and felt like the proposal was in another language, you're not alone. Here's the working glossary we hand to homeowners during in-home estimates.

Equipment terms

• SEER2 / EER2. The current efficiency rating for cooling equipment. Higher is better; the federal minimum in the South is SEER2 15.0. Trane XV systems hit SEER2 17–20+.
• AFUE. The efficiency rating for gas furnaces. 80% AFUE means 80% of the gas energy becomes heat. 95%+ AFUE is "high efficiency."
• HSPF2. The efficiency rating for heat-pump heating. Higher is better.
• Ton (cooling). 12,000 BTU/hr of cooling capacity. A 3-ton AC = 36,000 BTU/hr.
• BTU/hr. The standard unit for heating/cooling output.
• Single-stage / two-stage / variable-speed. How granularly the system can match output to demand. Variable-speed (Trane XV/XL) is quietest and best for humidity control.
• Heat pump. A system that moves heat instead of burning fuel — cools in summer, heats in winter.
• Dual-fuel. A heat pump + gas furnace hybrid that switches based on outdoor temperature.
• Mini-split (ductless). A heat pump with no ductwork — one outdoor unit + 1–8 indoor heads.

Comfort terms

• Manual J. The ACCA load calculation that determines how much heating/cooling your home actually needs. Skipping this leads to oversizing.
• Zoning. Splitting one HVAC system into multiple thermostat-controlled zones with motorized dampers.
• Static pressure. The resistance air encounters moving through the ductwork. High static = noisy + inefficient.
• Relative humidity (RH). The percent of moisture in the air. 40–50% is ideal indoors year-round.
• IAQ. Indoor air quality — covers filtration, humidity, UV, and ventilation.
• MERV. The filter-efficiency rating. MERV 13+ catches most pollen + dust.

Refrigerant terms

• R-410A. The refrigerant most existing Atlanta systems use. Being phased out.
• R-454B. The new low-GWP refrigerant for systems installed in 2025+.
• R-22 (Freon). Pre-2010 refrigerant. No longer manufactured. Servicing R-22 systems is expensive and a signal to plan replacement.

Cost terms

• Flat-rate pricing. The repair is priced by job, not hourly. (We use this — it removes the meter-running pressure.)
• Service-call fee. The trip + diagnostic charge. $89 standard, $99 diagnostic at Staton.
• 25C tax credit. Federal credit (up to $2,000 for heat pumps) for qualifying high-efficiency installs through 2032.
• Workmanship warranty. Covers the install labor — separate from the equipment warranty.
• Manufacturer warranty. Covers parts from the equipment maker (Trane: typically 10 years).

Service terms

• Tune-up. Twice-a-year maintenance visit (spring cooling, fall heating).
• Cap check. Capacitor testing — capacitors are the #1 part to fail in Atlanta heat.
• Coil clean. Removing dirt buildup from the evaporator/condenser. Critical for efficiency.
• Duct sealing (Aeroseal). Sealing duct leaks from the inside — typical Atlanta retrofit recovers 20–30% of conditioned air.
• Manual D. The ACCA duct-design calculation. Builders often skip it; we redo it on retrofits.
• Commissioning. The final-startup verification step where we measure airflow, refrigerant charge, and temperature split.
• Refrigerant charge. The exact amount of refrigerant in the system. Wrong charge kills efficiency + capacity.

If a glossary item is missing or a term on your estimate isn't clear, give us a call — we'll explain it in plain English. Contact us →