Furnace, Boiler, and Heat Pump Efficiency Ratings Explained

Heating and cooling equipment is rated by federally regulated efficiency numbers that tell you how much of the energy the equipment uses actually becomes useful heat or cooling. For furnaces and boilers, the rating is AFUE (Annual Fuel Utilization Efficiency). For heat pumps and air conditioners, the ratings are HSPF2, SEER2, and EER2. Understanding these numbers helps New Hampshire homeowners compare equipment fairly.

At A.J. LeBlanc Heating, we walk every replacement customer through these ratings before they choose equipment. Here is what each one means.

AFUE for furnaces and boilers

AFUE (Annual Fuel Utilization Efficiency) measures how much of the fuel a furnace or boiler burns actually ends up as useful heat in the home, averaged over a typical heating season. The remainder is lost up the flue or as standby losses.

Common AFUE ranges:

80 to 84 percent: baseline mid-efficiency. Common in older NH installations from before the 2010s.
87 to 90 percent: modern non-condensing oil and propane boilers.
92 to 96 percent: condensing gas and propane furnaces and boilers.
96 to 98+ percent: high-end condensing modulating boilers.

The federal minimum AFUE for new non-weatherized residential gas furnaces is 80 percent nationwide; there is no regional federal AFUE standard. The minimum is set to rise to 95 percent for furnaces manufactured on or after December 18, 2028, though that rule is under legal challenge.

How AFUE relates to real-world fuel use

The difference between an 80 percent and 95 percent AFUE furnace is roughly a 15 percent reduction in fuel use for the same amount of delivered heat, all else being equal. For an NH home with $1,500 in annual heating costs, that is about $225 per year in fuel savings.

Important caveat: real-world efficiency depends on more than the AFUE label. Oversized equipment short-cycles and underperforms its rated efficiency. Condensing boilers paired with high-temperature baseboard systems may never reach their condensing range, so they deliver only slight improvement over a quality non-condensing boiler.

HSPF2 for heat pumps in heating mode

HSPF2 (Heating Seasonal Performance Factor, version 2) measures how efficiently a heat pump delivers heating over a typical heating season. Higher is better.

The federal minimum HSPF2 for new split-system heat pumps is 7.5 nationwide, in effect since January 1, 2023; there is no regional heat pump minimum. The 8.1 figure you may see is the ENERGY STAR cold-climate threshold, not a federal minimum.
Quality cold-climate heat pumps achieve HSPF2 values of 9.0 to 11.0+.
HSPF2 replaced the old HSPF rating in 2023 under updated DOE test procedures. HSPF2 values are roughly 15 percent lower than the old HSPF for the same unit, so do not compare old and new ratings directly.

SEER2 and EER2 for cooling

SEER2 (Seasonal Energy Efficiency Ratio, version 2) measures average cooling efficiency over a typical cooling season.

EER2 measures cooling efficiency at a single high-load operating point.

Federal minimum SEER2 for new central AC in the northern region is currently 13.4.
Mid-tier residential equipment achieves SEER2 values of 14 to 16.
High-efficiency variable-speed equipment reaches SEER2 values of 18 to 24+.
Like HSPF2, SEER2 replaced the old SEER in 2023. SEER2 values are roughly 4 to 5 percent lower than the old SEER for the same unit.

Why ratings are only part of the story

Real-world equipment performance depends on more than the lab efficiency number:

Sizing: an oversized unit cycles on and off too often to hit its rated number.
Ductwork: leaky or undersized ducts waste cooling and heating capacity before it reaches the rooms.
Installation quality: refrigerant charge, airflow, and proper commissioning all affect real efficiency.
Controls: outdoor reset, modulating burners, and smart thermostats narrow the gap between rated and actual efficiency.

What ratings to look for in a NH home

Reasonable targets for southern NH residential equipment:

Gas or propane furnace: 95+ AFUE
Oil boiler: 87+ AFUE
Gas condensing boiler: 95+ AFUE
Cold-climate heat pump: HSPF2 9.0+ and SEER2 16+
Central AC: SEER2 15+

Schedule a replacement consultation

If you are evaluating equipment replacements and trying to make sense of the rating labels, contact A.J. LeBlanc Heating. We walk through the ratings, the real-world implications, and the rebate eligibility for each option. Serving New Hampshire families since 1928.

Frequently Asked Questions

Is a higher AFUE always worth it?

Not always. The fuel savings need to justify the higher equipment cost over the expected ownership period. For high-use households in cold climates like NH, the payback is usually favorable. For low-use applications or short ownership horizons, the simpler choice may be better.

What is the difference between SEER and SEER2?

SEER2 is the updated rating standard that took effect in 2023, using new test procedures that better reflect real-world conditions. SEER2 values are typically 4 to 5 percent lower than the old SEER for the same physical unit. Do not compare old SEER and new SEER2 ratings directly.

Does the AFUE label tell me my actual fuel cost?

Not directly. AFUE is an efficiency percentage. Your actual fuel cost depends on AFUE, fuel type, fuel price, and how much heat your home actually needs each year.

Why is the same equipment rated lower under SEER2 and HSPF2?

The new ratings use more realistic test conditions, including more representative external static pressure on the duct system. The equipment did not become less efficient; the measurement got more honest.

How do I find my current equipment's rating?

The yellow EnergyGuide label or the manufacturer's data plate on the equipment shows the AFUE, SEER2, EER2, or HSPF2 rating. Equipment manuals and online spec sheets also list these.