A. O. Smith HESF-40 1**
A. O. Smith HESF-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 37 gallons, a certified UEF of 0.92, and a certified first-hour rating of 64 gallons of hot water.
Its advertised UEF of 0.92 from A. O. Smith matches the certified 0.92 (Read Oct 5, 2026).
- Electric storage water heater
- 7 listed models
ENERGY STAR certification does not cover this type of water heater.
Certified figures
- Storage volume
- 37gallons
- UEF
- 0.92Uniform energy factor
- First-hour rating
- 64gallonsHot 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 | 37 gal storage volume | A. O. Smith | Read Oct 5, 2026 |
| Size | 37 gal | 37 gal storage volume | A. O. Smith | Read Oct 5, 2026 |
| UEF | 0.92 | 0.92 | A. O. Smith | Read Oct 5, 2026 |
| First-hour rating | 53 gal | 64 gal | A. O. Smith | Read Oct 5, 2026 |
Certified figures by listed model
| Model number | Storage volume (gal) | UEF | First-hour rating (gal) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|---|
| EEA12-40R55DVF 1** | 37 | 0.92 | 64 | 98% | Medium |
| EEA9-40R55DV 1** | 37 | 0.92 | 64 | 98% | Medium |
| EESU-40 1** | 37 | 0.92 | 64 | 98% | Medium |
| EEU6-40R45DV 1** | 37 | 0.92 | 64 | 98% | Medium |
| HESF-40 1** | 37 | 0.92 | 64 | 98% | Medium |
| HESFA-40 1** | 37 | 0.92 | 64 | 98% | Medium |
| PESU-40 1** | 37 | 0.92 | 64 | 98% | Medium |
UEF is the uniform energy factor. A dash means the model has no such figure.
It holds 37 gallons in the test, 3 gallons less than its 40-gallon sold size. It delivers 64 gallons of hot water in the test's first hour. That is 27 gallons more than its tank holds, since it reheats during the hour. In the first hour, 74 of the 477 electric storage models give more hot water. The median electric storage model gives 55 gallons in its first hour.
In the test, 8% of its energy does not reach the hot water (UEF 0.92). The daily hot water use in the test, called its draw pattern, was medium. Of 297 electric storage models with the same draw pattern, 81 have a higher UEF. On its draw pattern, its UEF is also the median electric storage UEF. When it reheats water in the test, 98% of the energy it uses ends up in the water.
It is sold under 7 model numbers in all. All of its test figures are shared by 8 other basic models. In all, 4 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.