Ariston ENS40LU-*
Ariston ENS40LU-* 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 AMERICAN STANDARD WATER HEATERS ENS40LU-*.
Certified figures
- Storage volume
- 36gallons
- UEF
- 0.91Uniform energy factor
- First-hour rating
- 41gallonsHot water in the first hour
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| Model number | Storage volume (gal) | UEF | First-hour rating (gal) | Recovery efficiency | Draw pattern |
|---|---|---|---|---|---|
| ES40S* | 36 | 0.91 | 41 | 98% | Low |
UEF is the uniform energy factor. A dash means the model has no such figure.
It holds 36 gallons in the test, 4 gallons less than its 40-gallon sold size. Starting full, it gives 41 gallons of hot water in its first hour of use. Its tank holds 36 gallons, so reheating adds 5 gallons during the first hour. In the first hour, 429 of the 477 electric storage models give more hot water. The median electric storage model gives 55 gallons in the first hour of the test.
In tests, 91% of the energy it uses ends up as hot water (UEF 0.91). In the test, daily hot water use was set to low (its draw pattern). Of 157 electric storage models with the same draw pattern, 81 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.
All of its test figures are shared by 2 other basic models. Of those, one or more are under the AMERICAN STANDARD WATER HEATERS and Lennox brands. For the full group, see the AMERICAN STANDARD WATER HEATERS ENS40LU-* page.
Also listed as
They carry every figure in the table above.
- Every Ariston basic model
- Every 40-gallon electric storage water heater
- Every electric storage water heater
Not covered
- Advertised figures. We have none on file for this model.