DoesTheMath

A. O. SMITH MHE6-40RW-035D-1** vs LOCHINVAR ENS-40W 1**: which uses less energy?

At the low draw pattern the A. O. SMITH MHE6-40RW-035D-1** uses 2,466 kWh a year and the LOCHINVAR 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.

Filed and computed figures
A. O. SMITH MHE6-40RW-035D-1** LOCHINVAR ENS-40W 1**
UEF (Uniform Energy Factor) 0.91 (better) 0.88
Energy use per year (kWh) 2,466 (better) 2,550
First hour rating (gal) 40 41
Rated storage volume (gal) 36 37
Installed cost range not published not published
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

A. O. SMITH MHE6-40RW-035D-1**: 2,466 kWh a year LOCHINVAR ENS-40W 1**: 2,550 kWh a year

A. O. SMITH MHE6-40RW-035D-1** — 2,466 kWh a year LOCHINVAR ENS-40W 1** — 2,550 kWh a year

A. O. SMITH MHE6-40RW-035D-1** is 84 kWh a year lower than LOCHINVAR ENS-40W 1**.

DOE CCD · 2026-09-19

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Enter your ZIP to price both units on the same rate where you live.

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 A. O. SMITH MHE6-40RW-035D-1** if running cost matters most: it uses 84 kWh less a year on the same test.
  • Pick the LOCHINVAR ENS-40W 1** if you need more hot water in your busiest hour: it lists a first hour rating of 41 gallons against 40.
  • 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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