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A. O. Smith G6-US4040NV 5**

A. O. Smith G6-US4040NV 5** is in the DOE listing as of Oct 26, 2026.

It has a labeled size of 40 gallons, a certified storage volume of 38 gallons, a certified UEF of 0.64, and a certified first-hour rating of 83 gallons of hot water.

Its advertised UEF of 0.64 from A. O. Smith matches the certified 0.64 (Read Oct 4, 2026).

  • Gas storage water heater
  • 2 listed models

Not listed as ENERGY STAR certified on Oct 26, 2026.

Storage volume
38gallons
UEF
0.64Uniform energy factor
First-hour rating
83gallonsHot water in the first hour
See it among every gas storage model

Advertised and certified figures

A. O. Smith G6-US4040NV 5**: advertised and certified
A. O. Smith G6-US4040NV 5**: advertised and certified Size: advertised 40 gal, certified 38 gal (advertised nominal size, certified storage volume). Size: advertised 38 gal, certified 38 gal (certified storage volume). UEF: advertised 0.64, certified 0.64. UEF: advertised 0.57, certified 0.64 (advertised up to). Size · advertised nominal size, certified storage volume Advertised 40 gal Certified 38 gal Size · certified storage volume Advertised 38 gal Certified 38 gal UEF Advertised 0.64 Certified 0.64 UEF · advertised up to Advertised 0.57 Certified 0.64
FigureAdvertisedCertifiedAdvertiserRead
Size 40 gal, nominal size 38 gal storage volume A. O. Smith Read Oct 4, 2026
Size 38 gal 38 gal storage volume A. O. Smith Read Oct 4, 2026
UEF 0.64 0.64 A. O. Smith Read Oct 4, 2026
UEF up to 0.57 0.64 A. O. Smith Read Oct 4, 2026
First-hour rating 83 gal 83 gal A. O. Smith Read Oct 4, 2026
First-hour rating 72 gal 83 gal A. O. Smith Read Oct 4, 2026

Certified figures by listed model

Model numberStorage volume (gal)UEFFirst-hour rating (gal)Recovery efficiencyDraw pattern
G6-US4040NV 5**380.648375%High
GURL-40 5**380.648375%High

UEF is the uniform energy factor. A dash means the model has no such figure.

It holds 38 gallons in the test, 2 gallons less than its 40-gallon sold size. Over one hour from a full tank, it gave 83 gallons in the test (its first-hour rating). Its tank holds 38 gallons, so reheating adds 45 gallons during the first hour. Among 763 gas storage models, 242 have a higher first-hour rating. Among gas storage models, the median first-hour rating is 78 gallons.

On Oct 26, 2026, this heater was not listed as ENERGY STAR certified. In the test, 36% of its energy does not reach the hot water (UEF 0.64). Its test simulated a day of high hot water use (its draw pattern). Of 434 gas storage models with the same draw pattern, 255 have a higher UEF. A UEF of 0.66 is the median for its type and draw pattern. Of the energy spent to reheat water, 75% goes into it (its recovery efficiency).

Its 2 model numbers are G6-US4040NV 5** and GURL-40 5**. Its test figures match those of 4 other basic models. They are listed under 4 other brands, one each.

Also listed as

They carry every figure in the table above.

Updated Oct 26, 2026 · Methodology

Not covered

  • Changes to an advertised figure after the date beside it.