A. O. Smith ENLB-40 1**
A. O. Smith ENLB-40 1** is in the DOE listing as of Oct 26, 2026.
It has a labeled size of 40 gallons, a certified storage volume of 35 gallons, a certified UEF of 0.92, and a certified first-hour rating of 51 gallons of hot water.
Its advertised UEF of 0.92 from Lowe's matches the certified 0.92 (Archived copy, Aug 7, 2025).
- Electric storage water heater
- 5 listed models
ENERGY STAR certification does not cover this type of water heater.
Certified figures
- Storage volume
- 35gallons
- UEF
- 0.92Uniform energy factor
- First-hour rating
- 51gallonsHot water in the first hour
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Change your hourAdvertised and certified figures
| Figure | Advertised | Certified | Advertiser | Read |
|---|---|---|---|---|
| Size | 40 gal, nominal size | 35 gal storage volume | A. O. Smith | Read Oct 4, 2026 |
| Size | 38 gal, nominal size | 35 gal storage volume | Lowe's | Archived copy, Aug 7, 2025 |
| Size | 36 gal | 35 gal storage volume | A. O. Smith | Read Oct 4, 2026 |
| UEF | 0.92 | 0.92 | Lowe's | Archived copy, Aug 7, 2025 |
| First-hour rating | 51 gal | 51 gal | Lowe's | Archived copy, Aug 7, 2025 |
Certified figures by listed model
| Model number | Storage volume (gal) | UEF | First-hour rating (gal) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|---|
| DEL-40 1** | 35 | 0.92 | 51 | 98% | Medium |
| E6-40L45DB 1** | 35 | 0.92 | 51 | 98% | Medium |
| E6-40L45DVB 1** | 35 | 0.92 | 51 | 98% | Medium |
| ENLB-40 1** | 35 | 0.92 | 51 | 98% | Medium |
| PNLB-40 1** | 35 | 0.92 | 51 | 98% | Medium |
UEF is the uniform energy factor. A dash means the model has no such figure.
It holds 35 gallons in the test, 5 gallons less than its 40-gallon sold size. It delivers 51 gallons of hot water in the test's first hour. That is 16 gallons more than its tank holds, since it reheats during the hour. In the first hour, 286 of the 477 electric storage models give more hot water. The median electric storage model gives 55 gallons in the first hour of the test.
In tests, 92% of the energy went to hot water, so its UEF is 0.92. In the test, daily hot water use was set to medium (its draw pattern). Of 297 electric storage models with the same draw pattern, 81 have a higher UEF and 2 a lower one. Its UEF is the median for its type and draw pattern. When it reheats water in the test, 98% of the energy it uses ends up in the water.
It is sold under 5 model numbers in all. There are 11 more basic models with the same test figures. In all, 8 other brands list one or more of them.
Also listed as
They carry every figure in the table above.
- Every A. O. Smith basic model
- Every 40-gallon electric storage water heater
- Every electric storage water heater
Not covered
- Changes to an advertised figure after the date beside it.