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Cooling

3 tools, 5 guides, 1 comparisons

Air conditioners, mini splits, refrigerant and SEER2 — the cool side of the manifold.

Thermal-toned outdoor condenser rejecting heat
A condenser rejecting the heat it pulled out of the house: the coil is the warm end.

Tools

SEER2 Savings Calculator

Cooling

Annual cooling cost and payback when you move from one SEER2 rating to another.

SEER2 · $/yr

Mini Split Sizing Calculator

Cooling

BTU/h per zone and how many heads a house actually needs.

BTU/h · zones

Superheat & Subcooling Calculator

Cooling

Target superheat and subcooling from pressures and temperatures, with the charge verdict.

°F · psig

SEER2 minimums

Minimum SEER2 by product class and region
Product classNationalSoutheast / Southwest
Split AC, under 45,000 BTU/h13.414.3
Split AC, 45,000 BTU/h and over13.413.8
Split heat pump14.3national only
Single-package AC13.4national only
Single-package heat pump13.4national only

Southeast: Alabama, Arkansas, Delaware, Florida, Georgia, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, Virginia, the District of Columbia and the U.S. Territories. Southwest: Arizona, California, Nevada and New Mexico, which also carries an EER2 floor. Regional air-conditioner standards apply at installation, not at manufacture.

Sources: 10 CFR 430.32(c)(6)(i)(A) (read 2026-09-04)

Guides

SEER2 Explained

Cooling

What changed in 2023, how SEER converts to SEER2, and the regional minimums.

9 min read

AC Not Cooling

Cooling

Running but not cold, frozen coil, compressor silent — a decision list.

12 min read

How Often to Change Your Filter

Cooling

Intervals by filter depth and MERV, and which way the arrow points.

7 min read

HVAC Zoning Systems

Cooling

Dampers, bypass, and why a zoned system needs a variable-speed blower.

10 min read

The R-454B Refrigerant Transition

Cooling

What the 2025 A2L changeover means for repairs, charging and parts.

9 min read

Comparisons

Ductless vs Central Air

Compare

Install cost, efficiency and zoning, for a house that has ducts and one that doesn't.

SEER2 · $/zone

Other sections

Sizing & Load

Manual J load, BTU/h, tonnage, duct sizing and static pressure — the numbers that decide what equipment goes in.

5 tools · 4 guides

Heating

Furnaces, heat pumps and the efficiency ratings that price them — AFUE, HSPF2 and the cold-climate question.

3 tools · 5 guides

Service & Costs

Replacement cost, maintenance, filters and the credits that move the price — what the job costs and what keeps it running.

4 tools · 5 guides