A. O. SMITH HPACO-45 1**+AXST-66 1**
3.7 UEF DOE CCD · 2026-09-19Grade C: where this UEF sits among the 194 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
An electric tank, high draw pattern (a larger household, or one where showers and laundry overlap).
Checking this model's running cost? Its annual energy use is 1,341 kWh of electricity at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 35 kWh above the class median of 1,306 kWh among 194 electric tank models, as calculated by this site from registry data.
Energy use per year
1,341 kWh a year
Computed by this site from the registry's UEF and the federal test's daily hot-water draw for this draw pattern. What it costs depends on the electricity rate where you live.
That is above the median of 1,306 kWh for the 194 models registered in the same heater type and draw pattern; it ranks 101 of 194, lowest energy first.
Solid line: this model (1,341 kWh). Dashed line: the class median.
Min 1,002 kWh Median 1,306 kWh Max 5,334 kWh
What it costs to run where you live
What the registry files
- UEF (Uniform Energy Factor) how much hot water you get for each unit of energy the heater uses
- 3.7 DOE CCD · 2026-09-19 Compared only with other models registered as an electric tank at the high draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- High DOE CCD · 2026-09-19
- First Hour Rating how many gallons of hot water the unit can deliver in one hour, starting from a full tank
- 82 gal DOE CCD · 2026-09-19
- Rated Storage Volume the tank size in gallons
- 60 gal DOE CCD · 2026-09-19
- On the market since (ENERGY STAR) the date the manufacturer told ENERGY STAR the model went on sale
- 2026-02-13 ENERGY STAR · 2026-09-19
- Connected / demand response (ENERGY STAR) whether the unit can take signals from your utility to shift when it heats, and by which standard (such as CTA-2045)
- Yes (CTA-2045-A,CTA-2045-B) ENERGY STAR · 2026-09-19
- Refrigerant and GWP (ENERGY STAR) the refrigerant a heat pump unit uses and its global warming potential, a leak's climate effect relative to carbon dioxide (CO2 = 1)
- R-744 (CO2), GWP 1 ENERGY STAR · 2026-09-19
What it costs to install
$3,505–$4,492 installed
Not a quote — a modeled range of what installers have charged for this class of unit; your price will vary with labor rates, access, and local code requirements.
Escalation indexes: equipment (BLS PPI) latest available: August 2026; labor (BLS ECI) latest available: April 2026 to June 2026.
NLR REMDB (BLS PPI/ECI escalated) · 2026-04-01Safety record
No CPSC recall names this model.
Checked against the CPSC recall database. CPSC does not publish a model-level match for this product category, so this list is curated by hand from the manufacturer's recall filings.
CPSC · 2026-09-24Does it fit your space?
Enter your own numbers below — this compares them to what ENERGY STAR publishes for this model, it does not tell you what to buy.
- Compressor operating range (ENERGY STAR)
- the air temperatures around the unit in which its heat pump runs; outside this range the heat pump stops
- Dimensions (ENERGY STAR)
- the unit's filed height, width, depth or tank diameter, in inches
- Input voltage and maximum current (ENERGY STAR)
- the circuit voltage the unit is certified on and the most current it draws
What these figures mean
How this compares
The closest models in the same class — same fuel, type and draw pattern.
Keep going
How every figure on this page is calculated
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Find what replaces your water heater
Enter the model number off your old unit and see what is on file today, with the yearly cost difference.
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Find a water heater that fits
Three questions — fuel, hot water need, install space — narrow every model on file to the ones that fit.
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What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
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What size heat pump water heater do I need?
Answered from what models in this size actually file.
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Water heaters
Every model on file with the Department of Energy, by heater type.
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All heat pump water heaters
Electric tanks that file a UEF of 2.0 or more — the registry has no separate heat pump type, so this site draws the line there.
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All CO₂ (R-744) heat pump water heaters
Heat pump models whose ENERGY STAR filing names R-744 (carbon dioxide) as the refrigerant, a global warming potential of 1.
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Every A. O. SMITH model on file
What this brand files, by heater type.
UEF 3.7 · Grade C Price it on your ZIP
The figure of 1,341 kWh for A. O. SMITH HPACO-45 1**+AXST-66 1** is calculated by this site, not by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, of 3.7 with the DOE test's daily hot-water draw for the high draw pattern. The source is DOE CCD, retrieved 2026-09-19. The class median for the 194 electric tank models registered at the high draw pattern is 1,306 kWh. This model sits 35 kWh above that median. It is 101st lowest in energy use of 194, which places it in the second-highest quarter of its class for energy use.
The high draw pattern describes a larger household, or one where showers and laundry overlap. The figure of 1,341 kWh applies to that pattern only. The registry lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 82 gallons for this unit, with a rated volume of 60 gallons. This page does not judge whether those values meet a particular household's demand. A household with a different draw pattern should not apply the 1,341 kWh figure, and this page has no value for other patterns. The selector by fuel, space and size filters models by those inputs, and the same-class replacement search by model number lists units in the class of HPACO-45 1**+AXST-66 1**.
Running cost is not written here because it depends on the reader's own utility electricity tariff. Multiplying 1,341 kWh by the rate per kilowatt-hour gives the yearly electricity cost at the federal test's draw. The cost calculator on your own ZIP does that step, and the page on how the annual cost is calculated sets out the method. Real use in a home can differ from the test's daily draw, and this page has no measured household data for A. O. SMITH HPACO-45 1**+AXST-66 1**. The installed price range appears in its own block with its source and date, as a modeled installed-cost range and not a quote, so it is not repeated here. The gap of 35 kWh to the class median of 1,306 kWh is a difference in energy until a rate is applied.
DOE CCD · 2026-09-19