A. O. SMITH ENS-40W 1** vs Lennox WHES040L45TN240S****: which uses less energy?
At the low draw pattern the Lennox WHES040L45TN240S**** uses 2,466 kWh a year and the A. O. SMITH ENS-40W 1** 2,550 — 84 kWh (3%) less, about 841 kWh over ten years. Both are filed as an electric tank, so the comparison holds. Enter your ZIP below to price the difference.
Side by side
Compared within one class only: models filed as an electric tank at the low draw pattern.
| Figure | A. O. SMITH ENS-40W 1** | Lennox WHES040L45TN240S**** |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.88 | 0.91 (better) |
| Energy use per year (kWh) | 2,550 | 2,466 (better) |
| First hour rating (gal) | 41 | 41 |
| Rated storage volume (gal) | 37 | 36 |
| Installed cost range | not published | not published |
| ENERGY STAR certified | not matched | not matched |
What it costs to run
Reliability
Not published: Reliability, failure rates and each model’s actual warranty term.
The registries these figures come from certify energy performance under a federal test; none of them records how long a unit lasts or how often it fails, so this page does not rank the two on reliability.
What is here instead:
- The filed efficiency, capacity and tank size of both models, side by side below.
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the Lennox WHES040L45TN240S**** if running cost matters most: it uses 84 kWh less a year on the same test.
- Pick the A. O. SMITH ENS-40W 1** if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Lennox WHES040L45TN240S****.
- Neither if your household's busiest hour needs more than 41 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.
Each model on its own
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A. O. SMITH ENS-40W 1**
Its filed figures, class position and running cost on your ZIP.
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Lennox WHES040L45TN240S****
Its filed figures, class position and running cost on your ZIP.