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Lochinvar ENS-40W 1**

Lochinvar ENS-40W 1** is in the DOE listing as of Oct 19, 2026.

  • Electric storage water heater
  • 1 listed model

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

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

Storage volume
37gallons
UEF
0.88Uniform energy factor
First-hour rating
41gallonsHot water in the first hour
See it among every electric storage model

Advertised and certified figures

Lochinvar ENS-40W 1**: advertised and certified
Lochinvar ENS-40W 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 0.88, certified 0.88. First-hour rating: advertised 41 gal, certified 41 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 0.88 Certified 0.88 First-hour rating Advertised 41 gal Certified 41 gal
FigureAdvertisedCertifiedAdvertiserRead
Size 40 gal, nominal size 37 gal storage volume Lochinvar Read Oct 4, 2026
Size 37 gal 37 gal storage volume Lochinvar Read Oct 4, 2026
UEF 0.88 0.88 Lochinvar Read Oct 4, 2026
First-hour rating 41 gal 41 gal Lochinvar Read Oct 4, 2026

Certified figures by listed model

Model numberStorage volume (gal)UEFFirst-hour rating (gal)Recovery efficiencyDraw pattern
LEM-40W 1**370.884198%Low

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 41 gallons in the test (its first-hour rating). Reheating lets it give 4 gallons beyond the 37 gallons in its tank. Of 477 electric storage models, 429 give more hot water in the first hour. The median electric storage model gives 55 gallons in the first hour of the test.

In tests, 88% of the energy it uses ends up as hot water (UEF 0.88). The daily hot water use in the test, called its draw pattern, was low. Of 157 electric storage models with the same draw pattern, 151 have a higher UEF. On its draw pattern, the median electric storage UEF is 0.92. When it reheats water in the test, 98% of the energy it uses ends up in the water.

There are 3 more basic models with the same test figures. The A. O. Smith, American, and State brands list one or more of them. For the full group, see the A. O. Smith ENS-40W 1** page.

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.