Lennox WHES040L45SN240B**** vs Rheem PROPH40 T0 RH120-M: 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 Rheem PROPH40 T0 RH120-M uses 802 kWh a year and the Lennox WHES040L45SN240B**** 2,439 — 1,638 kWh (67%) less, about 16,379 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 | Lennox WHES040L45SN240B**** | Rheem PROPH40 T0 RH120-M |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.92 | 2.8 (better) |
| Energy use per year (kWh) | 2,439 | 802 (better) |
| First hour rating (gal) | 46 | 45 |
| 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 | 2022-04-21 |
| 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 Rheem PROPH40 T0 RH120-M if running cost matters most: it uses 1,638 kWh less a year on the same test.
- Pick the Lennox WHES040L45SN240B**** if you need more hot water in your busiest hour: it lists a first hour rating of 46 gallons against 45.
- Neither if your household's busiest hour needs more than 46 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.
Each model on its own
- Lennox WHES040L45SN240B**** 2,439 kWh a year
- Rheem PROPH40 T0 RH120-M 802 kWh a year