A. O. SMITH GUF-40 1**
0.65 UEF DOE CCD · 2026-09-19Grade D: where this UEF sits among the 288 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
A gas tank, medium draw pattern (a typical three- or four-person household, about 55 gallons on a busy morning).
Checking the A. O. SMITH GUF-40 1**? At the medium draw pattern, the standard daily hot-water usage DOE tests against, it uses 171 therms of natural gas a year. That is 14 therms below the 185 therms median of the 288 gas tank models registered at that pattern.
Energy use per year
171 therms 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 natural gas rate where you live.
That is below the median of 185 therms for the 288 models registered in the same heater type and draw pattern; it ranks 33 of 288, lowest energy first.
Solid line: this model (171 therms). Dashed line: the class median.
Min 148 therms Median 185 therms Max 194 therms
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
- 0.65 DOE CCD · 2026-09-19 Compared only with other models registered as a gas 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
- 68 gal DOE CCD · 2026-09-19
- Rated Storage Volume the tank size in gallons
- 38 gal DOE CCD · 2026-09-19
What it costs to install
$1,702–$2,914 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 40-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 gas tank water heaters
Gas-fired storage tanks, every size and draw pattern on file.
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Every A. O. SMITH model on file
What this brand files, by heater type.
UEF 0.65 · Grade D Price it on your ZIP
The registry lists a UEF, the ratio of hot water delivered to energy used, of 0.65 for this model. This site combined that UEF with the DOE test's daily hot-water draw for the medium draw pattern to get 171 therms of natural gas a year. The registry does not publish that annual figure itself, and it applies only at that draw. The A. O. SMITH GUF-40 1** has the 33rd lowest energy use of 288 gas tank models, which places it in the lowest quarter of its class. Its use sits 14 therms below the class median of 185 therms. The source is the DOE CCD, retrieved 2026-09-19. Annual energy at other draw patterns is not available on this page. For the method, see how the annual cost is calculated.
This figure describes a household whose hot-water use resembles the medium draw pattern. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 68 gallons for this model, and the rated volume is 38 gallons. Those two values are the limits to check against a busy morning's demand. A household that draws well beyond the medium draw pattern would see use that differs from 171 therms, and the data here does not say how the unit performs at higher draws. The comparison with the class median of 185 therms holds only among gas tank models. It says nothing about electric or tankless units. To filter by fuel, space and size, use the water heater selector.
The registry gives no running cost for GUF-40 1**, because cost depends on the state average residential gas price, which differs by reader. Multiplying 171 therms by your own rate per therm gives the yearly gas cost at the medium draw pattern. The 14 therms gap to the class median of 185 therms can be priced the same way. The cost calculator does this from your ZIP. The installed price range appears in its own block on this page as a modeled installed-cost range, not a quote, so its figures are not repeated here. Actual use in your home is not available from the registry and may differ from the federal test's draw. To look for a same-class unit by model number, use find a same-class replacement.
DOE CCD · 2026-09-19