40,000 BTU furnaces
Every certified furnace at this input rating, gas and oil, ranked by AFUE — the share of fuel that becomes heat in the house.
Data current as of July 12, 2026 · 388 certified units · source AHRI + ENERGY STAR
Highest AFUE in this group
GE NF97X040V3BR*
AFUE 97.5 · $17.23 per MMBtu to run.
See installed costs →AFUE is the share of fuel a furnace turns into heat in your home. 96% AFUE wastes 4 cents of every dollar.
Every unit here is the same input rating, so the ranking is efficiency at a fixed size. Sizing is a heat-loss calculation, not a rule of thumb — a bigger furnace short-cycles rather than heating better.
The 20 highest-AFUE of 388 certified units · 1 with a verified place to buy
| Brand & model | AFUE | Input | Fuel | $/MMBtu | Buy |
|---|---|---|---|---|---|
| GE NF97X040V3BR* | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Get quotes |
| PHANTOM B97UR402V3BX* | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Get quotes |
| AIREASE A97US2V040B12X* | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Get quotes |
| LENNOX SL297UH040NV36B* | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Get quotes |
| DAIKIN DR96TC0403BN | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Get quotes |
| GOODMAN GRVT960403BN | 97.5 | 40,000 BTU | Natural Gas, Propane Gas | $17.23 | Buy |
| THERMAL ZONE TZ97UP2V040B3SA | 97.0 | 42,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| FUJITSU FF97TV304017UPS*A | 97.0 | 42,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| DURASTAR DR97UPAW0402317S | 97.0 | 42,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| RHEEM R972V0403A17UPS | 97.0 | 42,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| LENNOX ML297UH045XV36B* | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| GE NF97U030T2BR* | 97.0 | 30,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| GE NF97D045T3BR* | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| GE NF97U045T3BR* | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| GE NF97U045V3BR | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| COMFORT-AIRE GUH97T045B3MP | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| CONCORD 97G2UH030BE08*-* | 97.0 | 30,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| AIREASE A97UH2E030B08S*-* | 97.0 | 30,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| PHANTOM B97DR452E3B* | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
| PHANTOM B97UR452E3B* | 97.0 | 44,000 BTU | Natural Gas, Propane Gas | $17.32 | Get quotes |
Showing the top 20 by AFUE. All 388 certified units in this group are filterable in the full database — we rank here rather than dump, because a table nobody can read is not a resource.
Capacity and efficiency are AHRI-certified values; $/MMBtu is computed by us from EIA energy prices — see methodology. Input rating is the fuel the burner consumes; output is lower by exactly the AFUE.