A. O. Smith HPACO-45 1**+AXST-50S 1** vs American HPACO-45 1**+AXST-50T 1**: which uses less energy?
An asterisk in a model number stands for any character: one filing covers several variants.
At the medium draw pattern the A. O. Smith HPACO-45 1**+AXST-50S 1** and the American HPACO-45 1**+AXST-50T 1** use the same energy, 923 kWh a year each, on the same federal test. Both are filed as an electric tank, so the comparison holds; what separates them is below. Enter your ZIP to price either one on your own rate.
Side by side
Compared within one class only: models filed as an electric tank at the medium draw pattern.
| Figure | A. O. Smith HPACO-45 1**+AXST-50S 1** | American HPACO-45 1**+AXST-50T 1** |
|---|---|---|
| UEF (Uniform Energy Factor) | 3.52 | 3.52 |
| Energy use per year (kWh) | 923 | 923 |
| First hour rating (gal) | 70 | 67 |
| Rated storage volume (gal) | 46 | 45 |
| Installed cost range NLR REMDB | $3,030–$4,180 | $2,998–$4,170 |
| ENERGY STAR certified ENERGY STAR | yes | yes |
| Refrigerant ENERGY STAR | R-744 (CO2), GWP 1 | R-744 (CO2), GWP 1 |
| On the market since ENERGY STAR | 2026-02-13 | 2026-02-13 |
| CPSC recall naming it CPSC | none on file | none on file |
DOE CCD · 2026-09-19 NLR REMDB · 2026-04-01 ENERGY STAR · 2026-09-19 CPSC · 2026-09-24
What it costs to run
Reliability
Not published: Reliability, failure rates and each model’s actual warranty term.
The registries these figures come from certify energy performance under a federal test; none of them records how long a unit lasts or how often it fails, so this page does not rank the two on reliability.
What is here instead:
- The filed efficiency, capacity and tank size of both models, side by side above.
- No CPSC recall on file names either model (list checked 2026-09-24).
- Both are ENERGY STAR certified, which requires a manufacturer warranty of at least six years; the actual term for each model is not published.
- Time on the market, as filed with ENERGY STAR: the A. O. Smith HPACO-45 1**+AXST-50S 1** since 2026-02-13, the American HPACO-45 1**+AXST-50T 1** since 2026-02-13. A sale date, not a lifespan.
Which should you pick?
- Pick the A. O. Smith HPACO-45 1**+AXST-50S 1** if you need more hot water in your busiest hour: it lists a first hour rating of 70 gallons against 67.
- Neither if your household's busiest hour needs more than 70 gallons of hot water — neither lists more. Check whether a 50-gallon heater is enough.
Each model on its own
- A. O. Smith HPACO-45 1**+AXST-50S 1** 923 kWh a year
- American HPACO-45 1**+AXST-50T 1** 923 kWh a year