A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1)
A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) is a heat pump (hybrid electric) water heater from A. O. Smith with a 73 gallon rated tank and a 95 gallon first-hour rating at a 3.8 UEF — 1306 kWh/yr certified use, 58 in tall.
Our take
The 80-class member of the eight-brand CO₂ split family: a 73-gallon indoor tank at 58 inches — 6 under the class median — fed by an outdoor R-744 compressor (GWP 1) that runs to 1 °F. Certified numbers land at or above the middle: 3.80 UEF exactly on the class median, a 95-gallon first-hour rating 7 above it, about $222 a year High-draw. Connected-capable, 240 V at 20.2 A. Eighteen listings under 8 brand names, from GSW to John Wood, all one spec. The winter-proof compressor is what the integrated 90% of this class cannot offer.
Best for: Family-scale hot water from an unheated garage or outbuilding.
Trade-off: Split-system installation is a bigger, costlier job than a tank swap.
Efficiency
Uniform Energy Factor (UEF)
3.8
Annual electricity use
1306 kWh/yr
Recovery efficiency
423 %
General
Fuel
Electric
Capacity
First-hour rating
95 gal
Rated storage volume
73 gal
Draw pattern
High
Heat pump
Heat pump type
Split System HPWH
Refrigerant (GWP)
R-744 (CO₂) (GWP:1 | Lower GWP)
Compressor low-temp cutoff
1 °F
Installation
Input voltage
240
Max current draw
20.2 A
Smart features
Smart / connected capable
Yes
Dimensions
Height
58 in
Diameter
20 in
Certification
ENERGY STAR certified
Yes
Who is the A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) for?
Its 95 gallon first-hour rating suits a
household of 5+ people under DOE sizing guidance.
Estimated running cost: about $222/year at the national
average electricity rate (1306 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.
Also sold as
The A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) is certified hardware that A. O. Smith and its partner brands
publish under 18 names. The same specifications apply to every
variant:
Is the A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) ENERGY STAR certified?
Yes, the A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) holds a current ENERGY STAR certification for water heating efficiency (UEF 3.8).
How much does the A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) cost to run per year?
About $222 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 80-Gallon (HPACO-45 1-+AXST-80 1) need?
The A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 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 80-Gallon (HPACO-45 1-+AXST-80 1) a smart water heater?
Yes, the A. O. Smith Split System Heat Pump 80-Gallon (HPACO-45 1-+AXST-80 1) is connected-capable, with app control and eligibility for most utility demand-response programs.
