SEER Ratings, Tonnage & Duct Insulation: What It All Means

SEER measures cooling efficiency — higher is better. Think of it like miles per gallon for your AC. A SEER 16 system uses about 12% less electricity than a SEER 14 system to produce the same cooling. In a hot climate like Austin or Phoenix, that's roughly **$200-$400/year in savings**. Federal minimum is SEER 15 for southern states and SEER 14 for northern states (as of 2023). Premium systems reach SEER 20-26.

SEER2 is the updated testing standard introduced in 2023. It uses a more realistic testing procedure with higher external static pressure (basically, it assumes your ducts aren't perfect). SEER2 numbers are about 4-5% lower than SEER numbers for the same equipment. A SEER 16 system is roughly a SEER2 15.2. Don't panic if new quotes show lower numbers — it's the same equipment, just a different yardstick.

Tonnage measures how much heat your AC can remove from your home per hour. One ton = 12,000 BTUs of cooling per hour. A typical home needs 1 ton per 500-600 square feet, but this varies widely based on insulation, window quality, ceiling height, and climate. A 2,000 sq ft well-insulated home might need 3 tons, while a poorly insulated one might need 4.

AFUE measures furnace heating efficiency — how much of the fuel you pay for actually becomes heat. An 80% AFUE furnace wastes 20 cents of every dollar as exhaust heat. A 96% AFUE furnace wastes only 4 cents. In a cold climate where you spend $1,500/year on heating, upgrading from 80% to 96% AFUE saves about **$300/year**.

BTU is the basic unit of heating energy. Your furnace's BTU output determines how much it can heat your home. A 60,000 BTU furnace is typical for a 1,500 sq ft home; 80,000-100,000 BTU covers 2,000-2,500 sq ft. Like tonnage for cooling, the right BTU rating depends on your home's insulation, windows, and climate — not just square footage.

R-value measures how well duct insulation resists heat transfer. In an unconditioned space (attic, crawlspace), your ducts lose energy to the surrounding air. R-6 insulation means roughly 25% less energy loss than R-4.2. In a hot attic in Austin, that's the difference between your AC running efficiently and burning an extra **$15-$25/month** in summer.

Refrigerant is the chemical that carries heat between your indoor and outdoor units. R-410A has been standard since 2010 and is being phased down in favor of R-32 and R-454B due to environmental regulations. R-32 is slightly more efficient and has a lower global warming potential. New systems may use either — both work well.

This describes how your system modulates its output. **Single-stage** is full blast or off — like a light switch. **Two-stage** has a low and high setting — better comfort and efficiency. **Variable speed** adjusts continuously — whisper-quiet, even temperatures, and maximum efficiency. Variable speed costs $2,000-$4,000 more but uses 30-40% less energy than single-stage.