What are SEER and SEER2 ratings?

Cooling output per unit of electricity. And why SEER2 numbers read lower for the same machine after the 2023 test change. Plus why the highest rating isn't always the best buy.

◷ 4 min read

Quick Answer

SEER and SEER2 rate cooling efficiency. Cooling output divided by electricity used over a test season. SEER2 is the newer federal test, in use since January 1, 2023: the current rating for how efficiently a cooling system uses electricity across a season. It runs under conditions closer to real duct systems, so its numbers read slightly lower for the same machine. Higher means less electricity for the same cooling.

Card titled 'SEER → SEER2: Same Machine, Honester Test.' Left panel, 'SEER (pre-2023)': gentler test pressure, higher number, found on older systems. Right panel, 'SEER2 (2023 and after)': higher test pressure, closer to real ductwork, slightly lower number. Footer: 'SEER2 is miles-per-gallon for cooling — in force since January 1, 2023 (DOE). The rule: compare SEER2 to SEER2, SEER to SEER.' — SEER → SEER2: same machine, honester test. The 2023 test runs at higher pressure, closer to real ductwork, so the same machine shows a slightly lower number. The rule: compare SEER2 to SEER2, SEER to SEER. And never let the rating outrank sizing and installation quality.Tap or click to enlarge.

Before you call

When proposals land on your table, two quick checks protect you:

Line up SEER2 ratings next to total installed prices. Efficiency only counts per dollar spent.
If one quote shows SEER and another shows SEER2, ask for both in SEER2. Comparing across the two systems is comparing two different rulers.

How this works

Think miles per gallon, for AC units. The rating exists to make unlike machines comparable. Two systems can cool the same amount yet use very different amounts of electricity. The rating is the ratio. Cooling delivered per unit of power used, across a standard test season. A North Texas system runs for many hours a year, so even small rating gaps add up to real bill differences over a system's life.

SEER2 is the same idea under a tougher, more honest test. Federal testing changed on January 1, 2023. The new procedure runs system at higher external static pressure. Static pressure is the resistance air meets as it moves through the filter, coil. Ducts — so ratings better reflect installed reality. The practical result confuses shoppers: SEER2 numbers read slightly lower than SEER numbers for the same machine. A unit rated 15.2 SEER2 performs about the same as one rated about 16 under the old SEER test. The machine did not get worse; the ruler got stricter. Treat that pairing as a rough guide, not an exact conversion. The two tests differ, so the safe rule is to compare SEER2 with SEER2 and SEER with SEER.

	SEER (pre-2023)	SEER2 (2023– )
Test pressure	Lower (gentler)	Higher — closer to real ducts
Same machine's number	Higher	Slightly lower
Found on	Older installed systems, old stock quotes	All new equipment
Rule	Only compare within a family	Only compare within a family

Two warnings protect the rating's value. First, the rating is earned on a test bench. Your house is not a bench. Poor installation, bad ducts. Wrong sizing can waste the efficiency you paid for. A well-installed mid-tier system routinely beats a sloppy high-tier one. The rating is a property of the system. The efficiency you live with is a property of the installation.

Second, higher is not automatically better value. Each step up the rating ladder costs more and saves less than the step before it. Diminishing returns are built into the physics. In many homes, the same dollars do more work in duct sealing, insulation. Correct sizing than in the top rating tier. The right question is never "what's the highest SEER2?" It is "what does each tier save inmyhome, over the system's life, per dollar of price difference?" That is a payback question. Your contractor should answer it with your usage, not a brochure. And treat any guaranteed bill savings as fiction: ratings project; they do not promise.

When to call a professional

Bring mixed-rating proposals to one table and ask for the translation: both quotes restated in SEER2, with realistic savings and payback for your home. A pro answers with your run hours and your electric rate — not a national average.

What happens next

Ask Texas Heat & Air what an estimate for a replacement system costs before you book. Ask for tiers side by side, in SEER2, with the installed price attached to each. That is the form in which the rating becomes a decision instead of a slogan.

Texas Heat & Air next step

Comparing proposals with mixed rating systems? Bring both quotes — we will translate them onto one ruler: (682) 438-8127.

Go deeper:this question belongs to the full guideHVAC Engineering Explained Simply: How Cooling, Sizing, and Efficiency Really Work.

Sources

https://www.energy.gov/femp/purchasing-energy-efficient-residential-central-air-conditioners — U.S. Department of Energy guidance. Supports the SEER/SEER2 definitions, the 2023 test change to higher static pressure. The approximate 15.2 SEER2 ≈ 16 SEER relationship.