HVAC equipment

SEER2 replaced SEER because the old test understated real-world conditions. The M1 test procedure raises external static pressure five-fold, from 0.1 to 0.5 inches of water, to better reflect how equipment actually performs once it is connected to real ductwork. That is why a SEER2 number looks lower than the old SEER number for comparable equipment — it is a harder test, not worse equipment.

Minimum standards are set federally and vary by region for air conditioners, while heat pump minimums are national: split-system heat pumps must meet 14.3 SEER2 and 7.5 HSPF2, and single-package heat pumps 13.4 SEER2 and 6.7 HSPF2. Confirm the regional AC minimum for your state with your contractor or the manufacturer's regional compliance information.

New equipment is also in the middle of a refrigerant change. Lennox notes it is moving whole-home systems to R-454B and ductless to R-32, and that these refrigerants are not interchangeable with R-410A. Existing R-410A systems can keep being serviced, but supply of the old refrigerant is expected to tighten. That matters if you're deciding whether to nurse an old system along.

How to choose

Size is more important than brand or efficiency tier

ACCA Manual J determines the load, Manual S selects the equipment, Manual D designs the ducts. Skipping these is the single most common cause of an expensive system that doesn't feel good.

Heat pump or furnace depends on your climate and your electricity price

A heat pump moves heat instead of generating it, so it can heat and cool with one machine. Whether it beats a gas furnace on running cost depends entirely on local gas and electricity rates — ask for a side-by-side operating cost estimate.

Mini-splits are for homes without usable ducts

They're excellent for additions, garages, converted attics and old houses with no duct chases. They are usually not the cheapest answer if you already have good ductwork.

Match the indoor and outdoor unit

Replacing only the outdoor condenser and keeping a mismatched indoor coil can cost you the rated efficiency you paid for. Ask for the AHRI-matched system reference on the quote.

Ask which refrigerant the quoted system uses

It affects future service and line-set compatibility. Get it in writing on the proposal.