Ariston ENS40H-DR*** vs Friedrich PRO H40 T2 RH310BM: which uses less energy?
An asterisk in a model number stands for any character: one filing covers several variants.
At the medium draw pattern the Friedrich PRO H40 T2 RH310BM uses 928 kWh a year and the Ariston ENS40H-DR*** 3,531 — 2,603 kWh (74%) less, about 26,026 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 medium draw pattern.
| Figure | Ariston ENS40H-DR*** | Friedrich PRO H40 T2 RH310BM |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.92 | 3.5 (better) |
| Energy use per year (kWh) | 3,531 | 928 (better) |
| First hour rating (gal) | 58 | 60 |
| Rated storage volume (gal) | 36 | 36 |
| Installed cost range NLR REMDB | $1,591–$1,802 | not published |
| ENERGY STAR certified ENERGY STAR | not matched | yes |
| Refrigerant ENERGY STAR | not filed | R-134a, GWP 1430 |
| On the market since ENERGY STAR | not filed | 2021-01-31 |
| CPSC recall naming it CPSC | none on file | none on file |
DOE CCD · 2026-09-19 NLR REMDB · 2026-04-01 ENERGY STAR · 2026-09-19 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 Friedrich PRO H40 T2 RH310BM if running cost matters most: it uses 2,603 kWh less a year on the same test.
- Pick the Ariston ENS40H-DR*** if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Friedrich PRO H40 T2 RH310BM.
- Neither if your household's busiest hour needs more than 60 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.
Each model on its own
- Ariston ENS40H-DR*** 3,531 kWh a year
- Friedrich PRO H40 T2 RH310BM 928 kWh a year