Navien NPE-240S2 vs Navien NPE-240A2
Two of the gas tankless water heaters in our best gas tankless water heaters comparison, lined up spec by spec. Every figure comes from the manufacturer pages linked below, and the scores use the same published formula as the full ranking.
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Best for: Official UEF 0.96, maximum 5.8 GPM, minimum activation 1 GPM
Check price at AmazonBest for: Official UEF 0.95, maximum 5.6 GPM, minimum activation 1 GPM
Check price at AmazonSpec-by-spec comparison
Green marks the better published figure. "Not listed" means the manufacturer doesn't publish it.
| Spec | Navien NPE-240S2 | Navien NPE-240A2 | Weight |
|---|---|---|---|
| Uniform energy factorOfficial ENERGY STAR uniform energy factor. Higher means more hot water delivered per unit of fuel. Missing values take the category minimum. | 0.96 | 0.95 | 34% |
| Maximum flowOfficial ENERGY STAR maximum gallons per minute. This is a lab rating, not a guarantee at your incoming water temperature. Missing values take the category minimum. | 5.8 GPM | 5.6 GPM | 32% |
| Minimum activation flowOfficial ENERGY STAR minimum gallons per minute needed to start the heater. Lower is better for low-flow fixtures. Missing values take the category minimum (the highest minimum flow in the set). | 1 GPM | 1 GPM | 18% |
| Connected capableYes when the official ENERGY STAR record lists the model as connected-capable. Unstated counts as no. | No | No | 16% |
| Uniform energy factor (ENERGY STAR UEF) | 0.96 | 0.95 | info |
| Maximum flow (ENERGY STAR) | 5.8 GPM | 5.6 GPM | info |
| Minimum activation flow (ENERGY STAR) | 1 GPM | 1 GPM | info |
| Fuel (ENERGY STAR) | Natural Gas, Propane | Natural Gas, Propane | info |
| Vent type (ENERGY STAR) | Power Direct Vent | Power Direct Vent | info |
| Input rate (ENERGY STAR) | 199,000 BTU/h | 199,000 BTU/h | info |
| Annual natural-gas use (ENERGY STAR) | 176 therms/year | 178 therms/year | info |
| Maximum GPM per 10,000 BTU/h (computed) | 0.29 GPM per 10,000 BTU/h, computed as certified maximum GPM ÷ certified input rate | 0.28 GPM per 10,000 BTU/h, computed as certified maximum GPM ÷ certified input rate | info |
| Connected capable (ENERGY STAR) | No | No | info |
| Draw pattern (ENERGY STAR) | High-Usage | High-Usage | info |
| Recovery efficiency (ENERGY STAR) | Not listed | Not listed | info |
| Dimensions (ENERGY STAR) | 27 × 17 × 13 in (H × W × D) | 27 × 17 × 13 in (H × W × D) | info |
| Certified model number | NPE-240S2 | NPE-240A2 | info |
| Official brand name on the ENERGY STAR record | Navien | Navien | info |
| HeatPick score | 4.0/10 | 2.6/10 | 100% |
Where each one comes out ahead
Navien NPE-240S2
Better published figure on: Uniform energy factor, Maximum flow.
What we like
- High official maximum flow (5.8 GPM)
Watch out for
- Highest official minimum activation flow in this comparison (1 GPM)
- ENERGY STAR does not list this model as connected-capable
Navien NPE-240A2
No scored spec where it is strictly ahead; its case rests on the strengths below.
What we like
- Official certified ratings are published for every scored criterion
Watch out for
- Lowest official uniform energy factor in this comparison (0.95)
- Highest official minimum activation flow in this comparison (1 GPM)
- ENERGY STAR does not list this model as connected-capable
Verdict
Two official Navien 199,000 BTU/h-class records. The NPE-240S2 record lists a 0.96 UEF and 5.8 GPM maximum flow. The NPE-240A2 record lists a 0.95 UEF and 5.6 GPM maximum flow. Both official records list a 1.0 GPM minimum activation flow and do not mark the models as connected-capable. We do not infer a buffer tank or recirculation difference from the S and A letters alone, because those features are not in the ENERGY STAR fields we used.
- Navien NPE-240S2: ENERGY STAR Product Finder: NPE-240S2
- Navien NPE-240S2: ENERGY STAR certified water heaters dataset
- Navien NPE-240A2: ENERGY STAR Product Finder: NPE-240A2
- Navien NPE-240A2: ENERGY STAR certified water heaters dataset