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A. O. Smith PETX-40 1**

A. O. Smith PETX-40 1** is in the DOE listing as of Oct 19, 2026.

  • Electric storage water heater
  • 2 listed models

ENERGY STAR certification does not cover this type of water heater.

Its figures are also listed under A. O. Smith HESF-40 1**.

Storage volume
37gallons
UEF
0.92Uniform energy factor
First-hour rating
64gallonsHot water in the first hour
See it among every electric storage model

Advertised and certified figures

A. O. Smith PETX-40 1**: advertised and certified
A. O. Smith PETX-40 1**: advertised and certified Size: advertised 40 gal, certified 37 gal (advertised nominal size, certified storage volume). Size: advertised 37 gal, certified 37 gal (certified storage volume). UEF: advertised 0.92, certified 0.92. First-hour rating: advertised 64 gal, certified 64 gal. Size · advertised nominal size, certified storage volume Advertised 40 gal Certified 37 gal Size · certified storage volume Advertised 37 gal Certified 37 gal UEF Advertised 0.92 Certified 0.92 First-hour rating Advertised 64 gal Certified 64 gal
FigureAdvertisedCertifiedAdvertiserRead
Size 40 gal, nominal size 37 gal storage volume A. O. Smith Read Oct 5, 2026
Size 37 gal 37 gal storage volume A. O. Smith Read Oct 5, 2026
UEF 0.92 0.92 A. O. Smith Read Oct 5, 2026
First-hour rating 64 gal 64 gal A. O. Smith Read Oct 5, 2026

Certified figures by listed model

Model numberStorage volume (gal)UEFFirst-hour rating (gal)Recovery efficiencyDraw pattern
EEP12-40H55DVF 1**370.926498%Medium
PETX-40 1**370.926498%Medium

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

It holds 37 gallons in the test, 3 gallons less than its 40-gallon sold size. Over one hour from a full tank, it gave 64 gallons in the test (its first-hour rating). Reheating lets it give 27 gallons beyond the 37 gallons in its tank. Among 477 electric storage models, 74 have a higher first-hour rating. The median electric storage model gives 55 gallons in the first hour of the test.

In tests, 92% of the energy it uses ends up as hot water (UEF 0.92). Its test ran at the medium level of daily hot water use. Of 297 electric storage models with the same draw pattern, 81 have a higher UEF and 2 a lower one. Its UEF is the median for its type and draw pattern. The water took in 98% of the energy used to reheat it (its recovery efficiency).

It is the basic model for EEP12-40H55DVF 1** and PETX-40 1**. Its test figures match those of 8 other basic models. Besides this brand, 4 brands list one or more of them. You can find the whole group on the page for the A. O. Smith HESF-40 1**.

Also listed as

They carry every figure in the table above.

Updated Oct 19, 2026 · Methodology

Not covered

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