A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1)
A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) is a heat pump (hybrid electric) water heater from A. O. Smith with a 46 gallon rated tank and a 70 gallon first-hour rating at a 3.52 UEF.
| Uniform Energy Factor (UEF) | 3.52 |
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| Annual electricity use | 923 kWh/yr |
| Recovery efficiency | 429 % |
| Fuel | Electric |
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| First-hour rating | 70 gal |
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| Rated storage volume | 46 gal |
| Draw pattern | Medium |
| Heat pump type | Split System HPWH |
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| Refrigerant (GWP) | R-744 (CO₂) (GWP:1 | Lower GWP) |
| Compressor low-temp cutoff | 1 °F |
| Input voltage | 240 |
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| Max current draw | 20.2 A |
| Smart / connected capable | Yes |
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| Height | 46.6 in |
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| Diameter | 18 in |
| ENERGY STAR certified | Yes |
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Who is the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) for?
- Its 70 gallon first-hour rating suits a household of 3–4 people under DOE sizing guidance.
- Estimated running cost: about $157/year at the national average electricity rate (923 kWh/yr certified use).
- Needs a 240 V circuit; at 20.2 A max draw plan for a 30 A breaker (NEC 125% continuous-load rule).
- The heat pump compressor operates down to 1 °F ambient — below that, backup elements take over.
Similar water heaters
- A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50S 1) (UEF 3.52)
- A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45C 1-+AXST-50SC 1) (UEF 3.52)
- A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45C 1-+AXST-50SCTTP 1) (UEF 3.52)
- American Split System Heat Pump 50-Gallon (MHPCO-45 1-+MXST-50S 1) (UEF 3.52)
- American Split System Heat Pump 50-Gallon (MHPCO-45 1-+MXST-50STTP 1) (UEF 3.52)
- Giant Split System Heat Pump 50-Gallon (GTHPCO-45 1-+GTXST-50S 1) (UEF 3.52)
Frequently asked questions
Is the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) ENERGY STAR certified?
Yes, the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) holds a current ENERGY STAR certification for water heating efficiency (UEF 3.52).
How much does the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) cost to run per year?
About $157 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 electrical circuit does the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) need?
The A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) runs on a 240 V circuit drawing up to 20.2 A; per the NEC 125% continuous-load rule plan for at least a 30 A breaker (check the installation manual for the required circuit).
Is the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) a smart water heater?
Yes, the A. O. Smith Split System Heat Pump 50-Gallon (HPACO-45 1-+AXST-50STTP 1) is connected-capable, with app control and eligibility for most utility demand-response programs.
Sources
- data.energystar.gov (retrieved 2026-07-17)