Navien NPE-240S2
Navien NPE-240S2 is a gas tankless water heater from Navien rated 5.8 GPM at a 0.96 UEF.
| Uniform Energy Factor (UEF) | 0.96 |
|---|---|
| Annual gas use (natural gas) | 176 therms/yr |
| Annual propane use | 192.35 gal/yr |
| Fuel | Natural Gas, Propane |
|---|
| Max flow rate | 5.8 GPM |
|---|---|
| Draw pattern | High |
| Minimum activation flow | 1 GPM |
| Gas input rate | 199 kBTU/h |
|---|
| Max current draw | 5 A |
|---|---|
| Vent type | Power Direct Vent |
| Vent size | 2 |
| Smart / connected capable | No |
|---|
| Height | 27 in |
|---|---|
| Width | 17 in |
| Depth | 13 in |
| ENERGY STAR certified | Yes |
|---|
Real flow rate by climate
A tankless heater's usable flow depends on how far it must raise incoming water temperature. Sustained hot-water flow of the Navien NPE-240S2 at common temperature rises (a typical shower uses about 2 GPM of mixed water):
| Temperature rise | Climate | Sustained flow | Simultaneous showers |
|---|---|---|---|
| 45 °F | Warm climate (~75 °F groundwater) | 5.8 GPM | 2 |
| 55 °F | Mild climate (~65 °F groundwater) | 5.8 GPM | 2 |
| 70 °F | Cold climate (~50 °F groundwater) | 5.5 GPM | 2 |
| 77 °F | DOE test condition | 5 GPM | 2 |
Compare the Navien NPE-240S2
- Navien NPE-240S2 vs A. O. Smith ACTH-199M-(N,P) 1
- Navien NPE-240S2 vs A. O. Smith ATHR-160M 1
- Navien NPE-240S2 vs A. O. Smith ATHR-160M 1 (ATHR-160X3 1)
- Navien NPE-240S2 vs American ATHR-160M 1 (MTHR-160M 1)
- Navien NPE-240S2 vs American ATHR-160M 1 (MTHR-160X3 1)
- Navien NPE-240S2 vs American ATHR-180M 1 (MTHR-180M 1)
- Navien NPE-240S2 vs Bosch Greentherm (T9800 SE 160)
- Navien NPE-240S2 vs Bosch Greentherm (T9800 SEO 160)
Similar water heaters
- A. O. Smith ACTH-199M-(N,P) 1 (UEF 0.95)
- A. O. Smith T-H3-OS-N 1 (ACT-199O-N 1) (UEF 0.95)
- A. O. Smith T-H3-OS-N 1 (ACT-199O-P 1-1) (UEF 0.95)
- A. O. Smith T-H3-OS-N 1 (ATO-540H 1) (UEF 0.95)
- A. O. Smith T-H3-OS-N 1 (ATO-540H 1-1) (UEF 0.95)
- A. O. Smith T-H3-OS-N 1 (ATO-540HX3-N 1) (UEF 0.95)
Frequently asked questions
Is the Navien NPE-240S2 ENERGY STAR certified?
Yes, the Navien NPE-240S2 holds a current ENERGY STAR certification for water heating efficiency (UEF 0.96).
How much does the Navien NPE-240S2 cost to run per year?
About $255 per year at national average energy rates, based on its certified annual energy use under the DOE test draw pattern. Your rate and usage change this figure.
What venting does the Navien NPE-240S2 use?
The Navien NPE-240S2 uses Power Direct Vent venting with 2 in vent connections. Matching the existing vent type is usually the cheapest replacement path.
Is the Navien NPE-240S2 a smart water heater?
No, the Navien NPE-240S2 is not connected-capable — it has no app connectivity or demand-response support.
Sources
- data.energystar.gov (retrieved 2026-07-17)