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A. O. Smith FMDV-40 2**

A. O. Smith FMDV-40 2** 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 0.59, and a certified first-hour rating of 57 gallons of hot water.

Its advertised UEF of 0.59 from A. O. Smith matches the certified 0.59 (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
0.59Uniform energy factor
First-hour rating
57gallonsHot water in the first hour
See it among every gas storage model

Advertised and certified figures

A. O. Smith FMDV-40 2**: advertised and certified
A. O. Smith FMDV-40 2**: 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 0.59, certified 0.59. First-hour rating: advertised 57 gal, certified 57 gal. 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 0.59 Certified 0.59 First-hour rating Advertised 57 gal Certified 57 gal
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 0.59 0.59 A. O. Smith Read Oct 4, 2026
First-hour rating 57 gal 57 gal A. O. Smith Read Oct 4, 2026

Certified figures by listed model

Model numberStorage volume (gal)UEFFirst-hour rating (gal)Recovery efficiencyDraw pattern
FMDV-40 2**380.595776%Medium
G6-DMH4032NV 2**380.595776%Medium

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. Starting full, it gives 57 gallons of hot water in its first hour of use. That is 19 gallons more than its tank holds, since it reheats during the hour. Among 763 gas storage models, 717 have a higher first-hour rating. The median gas storage model gives 78 gallons in its first hour.

On Oct 26, 2026, this heater was not listed as ENERGY STAR certified. In the test, 41% of its energy does not reach the hot water (UEF 0.59). Its test simulated a day of medium hot water use (its draw pattern). Of 288 gas storage models with the same draw pattern, 185 have a higher UEF and 58 a lower one. For its type and draw pattern, the median UEF is 0.60. Of the energy spent to reheat water, 76% goes into it (its recovery efficiency).

It is the basic model for FMDV-40 2** and G6-DMH4032NV 2**. There are 4 more basic models with the same test figures. Each of the 4 other brands lists one of them.

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.