SEER and SEER2.

SEER stands for Seasonal Energy Efficiency Ratio. It is cooling output divided by electrical input across a modelled season, so a higher number means more cooling per unit of electricity.

SEER2 is the same idea measured under a revised test procedure that began applying in 2023. The new test uses higher external static pressure, which is closer to a real duct system than the old one was. Because the test is harder, a given piece of equipment carries a slightly lower SEER2 number than it would have carried as SEER. The machine did not get worse.

So do not compare a SEER number from an old brochure against a SEER2 number from a new one and conclude anything.

Why the sticker is not your bill

The rating is a laboratory figure for the equipment. What your house actually gets depends on things the lab never saw:

• Duct leakage, which is frequently the largest single loss
• Whether the system is correctly sized for the house
• Refrigerant charge being right
• A condenser coil clean enough to reject heat
• Insulation, windows, and what your roof does on a 115 degree day

A high rated system with a fouled coil and leaky ducts will lose to a modest one that is clean and correctly charged. This is not an argument against efficient equipment. It is an argument against expecting the sticker to show up on your bill by itself.

What this means for you

Maintenance affects your running cost more reliably than the rating does, and it is the part you can still change on equipment you already own. Charge, airflow and a clean coil are measurable, and a check-up writes all three down so you can compare next year.

Nobody here sells equipment, so this page has nothing to gain from telling you to buy a bigger number.