A. O. SMITH GCB-40 4**
0.64 UEF DOE CCD · 2026-09-19Grade G: where this UEF sits among the 414 models in its class, lowest (G) to highest (A). A position, not an official label. How the grade is set
A gas tank, high draw pattern (a larger household, or one where showers and laundry overlap).
Verifying the figures for A. O. SMITH GCB-40 4**? This gas tank heater uses 264 therms of natural gas a year at the high draw pattern, the standard daily hot-water usage DOE tests against. That is 4 therms above the class median of 260 therms across the 414 gas tank models at that draw pattern.
Energy use per year
264 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 above the median of 260 therms for the 414 models registered in the same heater type and draw pattern; it ranks 236 of 414, lowest energy first.
Solid line: this model (264 therms). Dashed line: the class median.
Min 188 therms Median 260 therms Max 277 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
- 0.64 DOE CCD · 2026-09-19 Compared only with other models registered as a gas 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
- 78 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
$1,643–$2,763 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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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 0.64 · Grade G Price it on your ZIP
The figure of 264 therms is not a registry value. This site computed it from the registry's UEF, the ratio of hot water delivered to energy used, which is 0.64 for this model, and from the DOE test's daily hot-water draw for the high draw pattern. The fuel is natural gas, and the source is DOE CCD, retrieved 2026-09-19. Among the 414 gas tank models at this draw pattern, A. O. SMITH GCB-40 4** ranks 236th lowest for energy use. Its gap of 4 therms above the 260 therms median places it in the second-highest quarter of its class for energy use. The methodology page explains how the annual figures are calculated.
The high draw pattern describes a larger household, or one where showers and laundry overlap, so the 264 therms figure applies to that kind of use only. A household with a different draw pattern would have a different figure, and this page does not calculate one. The registry lists a first hour rating, the gallons of hot water available in the first hour from a full tank, of 78 gallons, with a rated volume of 38 gallons. Those values describe capacity under the test conditions. The registry does not state how many people this capacity serves, and this page does not estimate it. To compare units by fuel, space and size, use the water heater selector.
The running cost is not written in this text, because it depends on the state average residential gas price for the reader's location. The cost is 264 therms priced at that rate, and the 4 therms above the class median of 260 therms is priced the same way. Enter your ZIP in the cost calculator to see the result for your state. The modeled installed-cost range appears in its own block on the page, with its source and date, and it is not a quote. If you need a unit in the same class as GCB-40 4**, you can find a same-class replacement by model number. The comparison with the class holds only for the high draw pattern.
DOE CCD · 2026-09-19