A. O. SMITH ENJ-40W 1**
0.91 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 163 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
An electric tank, low draw pattern (a one- or two-person household).
At the low draw pattern, the standard daily hot-water usage DOE tests against, the A. O. SMITH ENJ-40W 1** uses 2,466 kWh of electricity a year. Low means a one- or two-person household. That is 27 kWh above the class median of 2,439 kWh, at 88th lowest of 163.
Energy use per year
2,466 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 2,439 kWh for the 163 models registered in the same heater type and draw pattern; it ranks 88 of 163, lowest energy first.
Solid line: this model (2,466 kWh). Dashed line: the class median.
Min 724 kWh Median 2,439 kWh Max 2,550 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
- 0.91 DOE CCD · 2026-09-19 Compared only with other models registered as an electric tank at the low draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- Low 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
- 38 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
Not published: Installed cost range
This model's UEF lies outside the range NLR REMDB's cost model was fitted on, and the range is not stretched past it.
The annual energy figure on this page does not depend on this range and is unaffected.
Safety 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 0.91 · Grade G Price it on your ZIP
This figure is computed by this site, not published by the registry. It combines the registry's UEF, the ratio of hot water delivered to energy used, with the daily hot-water draw of the DOE test. The registry lists a UEF of 0.91 for this model. The result is 2,466 kWh of electricity a year, from DOE CCD data retrieved 2026-09-19. It is a calculated value, not a measurement from a home. Actual use in a home depends on how much hot water that home draws. Figures for other draw patterns are not given here. The steps are set out in how the annual cost is calculated.
Among the 163 models registered as an electric tank at the low draw pattern, this one ranks 88th lowest for energy use. That places it in the second-highest quarter of its class. Its use is 27 kWh above the class median of 2,439 kWh. The model has a first hour rating, the gallons of hot water available in the first hour from a full tank, of 38 gallons. Its rated volume is 35 gallons. The energy figure applies to a one- or two-person household's hot-water use, so it does not describe a larger household. A reader ranking on energy use alone will find models in the class that use less. For a different fuel or size, use the water heater selector by fuel, space and size.
The running cost is not written here, because it depends on your own utility electricity rate. Multiply 2,466 kWh by your rate per kilowatt-hour to get the yearly cost at the low draw pattern. The cost calculator on your own ZIP does this from your ZIP code. Multiplying 27 kWh the same way gives the cost of the difference from the class median. An installed price range is not published for this model. Its ratings lie outside the range the cost database's model was fitted on. That range is not stretched past it. To look up a unit in the same class, use find a same-class replacement by model number.
DOE CCD · 2026-09-19