AC size, SEER2 and the new refrigerants, explained for Vegas

Last checked October 29, 2026

Bigger isn't better: an oversized AC short-cycles, wears out faster and costs more, so ask for a Manual J load calculation. New AC installed in Nevada must meet Southwest minimums, at least 14.3 SEER2 for a typical home split system. And since 2025 new systems use new refrigerants (R-454B or R-32), which local contractors say pushed prices up.

What a "ton" means

One ton of cooling is 12,000 BTU per hour. The name comes from the heat a ton of ice soaks up melting over a day. A 4 ton AC moves about 48,000 BTU of heat out of your house every hour.

Why sizing matters more than people think

The right size comes from a Manual J load calculation, the industry standard from ACCA. It looks at your insulation, windows, air leaks and appliances, not just square feet.

An oversized unit cools in short bursts, which wears it out faster, controls humidity worse and costs more upfront. A DOE fact sheet recommends Manual J for the load and Manual S for picking equipment, and notes that in one survey nearly 40% of contractors said they oversize on purpose. If a quote just matches your old unit's size, ask why.

SEER2 and Nevada's minimums

SEER2 is the efficiency rating. It replaced SEER in 2023 with a tougher test, so a unit's SEER2 number reads lower than its old SEER number. Nevada is in the DOE's Southwest region with Arizona, California and New Mexico, which has stricter rules: since January 1, 2023, only units meeting these can be installed here.

Equipment	Southwest minimum
Split AC under 45,000 BTU/h (most homes)	14.3 SEER2 and 11.7 EER2
Split AC 45,000 BTU/h and up	13.8 SEER2 and 11.2 EER2
Package AC (often on Vegas roofs)	13.4 SEER2 and 10.6 EER2
Split heat pump	14.3 SEER2 and 7.5 HSPF2
Package heat pump	13.4 SEER2 and 6.7 HSPF2

EER2 matters here because it measures efficiency at peak heat, which is most of a Vegas summer. Going above the minimum costs more upfront; whether it pays back depends on your bill and how long you'll stay.

The refrigerant switch

New systems: home AC and heat pumps made since January 1, 2025 use new refrigerants, mainly R-454B and R-32. Both are rated lower-flammability (A2L), so new systems include a leak sensor.
Old R-410A systems: an EPA rule effective July 27, 2026 dropped the January 1, 2026 install deadline. R-410A systems made before 2025 can still be installed until stock runs out. Repair parts and refrigerant are still made, but production is being cut, and ACCA expects refrigerant prices to rise significantly.
Not a drop-in: you can't put the new refrigerant in an R-410A system. Line sets can often be reused.
Price impact: one Las Vegas contractor says installed prices rose 10 to 20% in 2025 with the switch. That's one company's read, not an industry figure.

Common questions

What SEER2 is required in Nevada?

Nevada is in the DOE Southwest region. Since January 1, 2023, a new split AC under 45,000 BTU/h installed here must be at least 14.3 SEER2 and 11.7 EER2. Larger split systems and package units have slightly lower minimums.

What size AC do I need for my Las Vegas home?

There is no honest answer from square footage alone. The right size comes from a Manual J load calculation, which looks at insulation, windows, air leaks and sun. One ton is 12,000 BTU per hour of cooling.

Can I still buy an R-410A system?

Yes, if it was made or imported before January 1, 2025. An EPA rule effective July 27, 2026 dropped the old January 1, 2026 install deadline, so leftover stock can be installed until it runs out. Parts and refrigerant for repairs are still made.

Is the new refrigerant safe?

R-32 and R-454B are rated "lower flammability" (A2L). That is why new systems come with a refrigerant leak sensor. Installed correctly, they meet current codes.

Sources

Rules, rebates and prices change. If something here is out of date, tell us on the share page and we'll fix it.