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A. O. Smith GUF-50 1**

A. O. Smith GUF-50 1** is in the DOE listing as of Oct 26, 2026.

It has a labeled size of 50 gallons, a certified storage volume of 48 gallons, a certified UEF of 0.70, and a certified first-hour rating of 83 gallons of hot water.

Its advertised UEF of 0.70 from A. O. Smith matches the certified 0.70 (Read Oct 5, 2026).

  • Gas storage water heater
  • 2 listed models

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

Storage volume
48gallons
UEF
0.70Uniform 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 GUF-50 1**: advertised and certified
A. O. Smith GUF-50 1**: advertised and certified Size: advertised 50 gal, certified 48 gal (advertised nominal size, certified storage volume). Size: advertised 48 gal, certified 48 gal (certified storage volume). UEF: advertised 0.70, certified 0.70. UEF: advertised 0.70, certified 0.70 (advertised up to). Size · advertised nominal size, certified storage volume Advertised 50 gal Certified 48 gal Size · certified storage volume Advertised 48 gal Certified 48 gal UEF Advertised 0.70 Certified 0.70 UEF · advertised up to Advertised 0.70 Certified 0.70
FigureAdvertisedCertifiedAdvertiserRead
Size 50 gal, nominal size 48 gal storage volume A. O. Smith Read Oct 5, 2026
Size 48 gal 48 gal storage volume A. O. Smith Read Oct 5, 2026
UEF 0.70 0.70 A. O. Smith Read Oct 5, 2026
UEF up to 0.70 0.70 A. O. Smith Read Oct 5, 2026
First-hour rating 83 gal 83 gal A. O. Smith Read Oct 5, 2026

Certified figures by listed model

Model numberStorage volume (gal)UEFFirst-hour rating (gal)Recovery efficiencyDraw pattern
G12-UFDT5040NV 1**480.708373%High
GUF-50 1**480.708373%High

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

It holds 48 gallons in the test, 2 gallons less than its 50-gallon sold size. It delivers 83 gallons of hot water in the test's first hour. That is 35 gallons more than its tank holds, since it reheats during the hour. In the first hour, 242 of the 763 gas storage models give more hot water. Among gas storage models, the median first-hour rating is 78 gallons.

It was not listed as ENERGY STAR certified on Oct 26, 2026. In the test, 30% of its energy does not reach the hot water (UEF 0.70). The daily hot water use in the test, called its draw pattern, was high. Of 434 gas storage models with the same draw pattern, 111 have a higher UEF and 283 a lower one. On its draw pattern, the median gas storage UEF is 0.66. The water took in 73% of the energy used to reheat it (its recovery efficiency).

Its 2 model numbers are G12-UFDT5040NV 1** and GUF-50 1**. There are 3 more basic models with the same test figures. Those basic models are sold with American, RELIANCE WATER HEATERS, and State as their brand names.

It may qualify for 2 rebate programs.

Also listed as

They carry every figure in the table above.

Rebates

ProgramStateStatusProgram page
Xcel Energy MINNESOTA RESIDENTIAL ENERGY EFFICIENCY PROGRAMS (gas storage, gas tankless) MN May qualify Its own page
Avista Home and small commercial: HVAC and water heating incentives (gas storage) WA May qualify Its own page

Programs change their terms. Check the program's own page before you buy.

Updated Oct 26, 2026 · Methodology

Not covered

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