A. O. Smith ENS-30 1** vs MRCOOL MTWH04530E: which uses less energy?
An asterisk in a model number stands for any character: one filing covers several variants.
At the low draw pattern the MRCOOL MTWH04530E uses 2,439 kWh a year and the A. O. Smith ENS-30 1** 2,522 — 82 kWh (3%) less, about 822 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-30 1** | MRCOOL MTWH04530E |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.89 | 0.92 (better) |
| Energy use per year (kWh) | 2,522 | 2,439 (better) |
| First hour rating (gal) | 47 | 47 |
| Rated storage volume (gal) | 27 | 28 |
| Installed cost range NLR REMDB | not published | $1,475–$1,602 |
| CPSC recall naming it CPSC | none on file | none on file |
DOE CCD · 2026-09-19 NLR REMDB · 2026-04-01 CPSC · 2026-09-24
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 above.
- No CPSC recall on file names either model (list checked 2026-09-24).
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the MRCOOL MTWH04530E if running cost matters most: it uses 82 kWh less a year on the same test.
- Pick the A. O. Smith ENS-30 1** if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the MRCOOL MTWH04530E.
- Neither if your household's busiest hour needs more than 47 gallons of hot water — neither lists more. Check whether a 30-gallon heater is enough.
Each model on its own
- A. O. Smith ENS-30 1** 2,522 kWh a year
- MRCOOL MTWH04530E 2,439 kWh a year