SEER2, EER2 and HSPF2 Efficiency Ratings

What it is

The US Department of Energy sets the test procedure for central air conditioners and heat pumps in 10 CFR 430, Subpart B, Appendix M1. AHRI 210/240 is the industry rating standard that follows it. On January 1, 2023, the M1 procedure replaced the older Appendix M, and the ratings gained a "2." The main change was a higher external static pressure during testing, which is closer to real ductwork. The result is that a SEER2 number is lower than the SEER number for the same equipment.

How to read it

Each rating is a ratio of cooling or heating output to electrical input. Higher is more efficient. Ratings apply to a certified combination of outdoor unit and indoor coil or air handler, listed in the AHRI directory. A rating for an outdoor unit alone is incomplete.

The ratings

Key points

• SEER2 and SEER are not directly comparable. Do not compare a new SEER2 rating to an old SEER rating as if they were the same scale.
• Minimum efficiency levels are in 10 CFR 430.32. For split air conditioners, the minimum depends on the region (North, Southeast, Southwest). Check the current table and the installation location.
• In the Southeast and Southwest regions, compliance for split air conditioners is tied to the installation date and location, not only the manufacture date. Contractors are responsible for installing compliant systems.
• Utility rebates and tax credits often use their own thresholds, sometimes based on ENERGY STAR or CEE tiers. Check the program rules.
• The AHRI certificate number ties a specific outdoor and indoor model pair to its rating. Keep it with the sale.

Common mistakes

• Quoting a SEER2 rating for an outdoor unit without the matched coil.
• Telling a customer a new system is "less efficient" because its SEER2 is lower than the old unit's SEER.
• Selling a split air conditioner for a Southern installation that only meets the Northern minimum.
• Using EER2 and SEER2 interchangeably.

Governing standards: 10 CFR 430 Subpart B, Appendix M1 (test procedure); 10 CFR 430.32 (efficiency standards); AHRI 210/240.

Reference only. Verify against the current governing code or standard, the manufacturer's data and the project documents before use. Apps for Distributors disclaims liability arising from reliance on this reference.