Bock RE240LN*-***** vs Lennox WHES040L45SN240B****: 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 Bock RE240LN*-***** and the Lennox WHES040L45SN240B**** use the same energy, 2,439 kWh a year each, on the same federal test. Both are filed as an electric tank, so the comparison holds; what separates them is below. Enter your ZIP to price either one on your own rate.
Side by side
Compared within one class only: models filed as an electric tank at the low draw pattern.
| Figure | Bock RE240LN*-***** | Lennox WHES040L45SN240B**** |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.92 | 0.92 |
| Energy use per year (kWh) | 2,439 | 2,439 |
| First hour rating (gal) | 45 | 46 |
| Rated storage volume (gal) | 34 | 36 |
| Installed cost range NLR REMDB | $1,562–$1,752 | $1,591–$1,802 |
| 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 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 30-gallon heater is enough.
Each model on its own
- Bock RE240LN*-***** 2,439 kWh a year
- Lennox WHES040L45SN240B**** 2,439 kWh a year