A. O. SMITH ENJB-40 1**
0.94 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 426 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
An electric tank, medium draw pattern (a typical three- or four-person household, about 55 gallons on a busy morning).
If you are checking this water heater's energy figure, here it is. The A. O. SMITH ENJB-40 1** uses 3,456 kWh a year at the medium draw pattern, the standard daily hot-water usage DOE tests against. That is 75 kWh below the class median of 3,531 kWh across 426 electric tank models.
Energy use per year
3,456 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 below the median of 3,531 kWh for the 426 models registered in the same heater type and draw pattern; it ranks 137 of 426, lowest energy first.
Solid line: this model (3,456 kWh). Dashed line: the class median.
Min 773 kWh Median 3,531 kWh Max 3,569 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
- 0.94 DOE CCD · 2026-09-19 Compared only with other models registered as an electric tank at the medium draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- Medium 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
- 57 gal DOE CCD · 2026-09-19
- Rated Storage Volume the tank size in gallons
- 35 gal DOE CCD · 2026-09-19
What it costs to install
$1,589–$2,210 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 · 2026-09-24What 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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Is a 30-gallon water heater enough?
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 electric resistance tank water heaters
Electric tanks that file a UEF below 2.0 — heated by elements, not a heat pump.
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Every A. O. SMITH model on file
What this brand files, by heater type.
UEF 0.94 · Grade G Price it on your ZIP
The figure of 3,456 kWh comes from this site, not from the registry. The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.94 for this model. This site divides the DOE test's daily hot-water draw for the medium draw pattern by that UEF. The source is DOE CCD, retrieved 2026-09-19. Against the class median of 3,531 kWh, the model uses 75 kWh less per year at the medium draw pattern. That puts it 137th lowest of 426 models, in the second-lowest quarter of its class for energy use. The method behind the annual cost is explained on its own page.
The heater is an electric tank with a rated volume of 35 gallons. Its first hour rating, the gallons of hot water available in the first hour from a full tank, is 57 gallons. The medium draw pattern describes a typical three- or four-person household with the hot-water use of a busy morning. A household of that size is the case the 3,456 kWh figure describes. A household with a heavier or lighter daily draw would use a different amount, and this page does not estimate it. The energy figure does not show whether this tank size meets a particular home's demand. The water heater selector filters by fuel, space and size.
The running cost is not stated in the text because it depends on your own utility electricity tariff. The annual energy of 3,456 kWh at the medium draw pattern is the input to that calculation. The cost calculator on your own ZIP applies your rate to that figure. A different rate gives a different cost from the same 3,456 kWh. The installed price range is shown in its own block, with its source and date, as a modeled range and not a quote. The 75 kWh gap from the class median is a difference in energy, not in cost. To find another model in the same class, use the replacement lookup by model number.
DOE CCD · 2026-09-19