DoesTheMath

Lennox WHHP050T45MD240S**** vs Rheem PROPH50 T2 RH400-30: which uses less energy?

At the medium draw pattern the Rheem PROPH50 T2 RH400-30 uses 837 kWh a year and the Lennox WHHP050T45MD240S**** 848 — 11 kWh (1%) less, about 109 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.

Filed and computed figures
Lennox WHHP050T45MD240S**** Rheem PROPH50 T2 RH400-30
UEF (Uniform Energy Factor) 3.83 3.88 (better)
Energy use per year (kWh) 848 837 (better)
First hour rating (gal) 69 67
Rated storage volume (gal) 45 45
Installed cost range $3,033–$4,480 $3,039–$4,530
ENERGY STAR certified yes yes
Refrigerant R-513A, GWP 630 R-134a, GWP 1430
On the market since 2025-12-01 2024-06-24
DOE CCD · 2026-09-19

What it costs to run

Lennox WHHP050T45MD240S****: 848 kWh a year Rheem PROPH50 T2 RH400-30: 837 kWh a year

Lennox WHHP050T45MD240S**** — 848 kWh a year Rheem PROPH50 T2 RH400-30 — 837 kWh a year

Rheem PROPH50 T2 RH400-30 is 11 kWh a year lower than Lennox WHHP050T45MD240S****.

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.
  • Both are ENERGY STAR certified, which requires a manufacturer warranty of at least six years; the actual term for each model is not published.
  • Time on the market, as filed with ENERGY STAR: the Lennox WHHP050T45MD240S**** since 2025-12-01, the Rheem PROPH50 T2 RH400-30 since 2024-06-24. A sale date, not a lifespan.

Which should you pick?

  • Pick the Rheem PROPH50 T2 RH400-30 if running cost matters most: it uses 11 kWh less a year on the same test.
  • Pick the Lennox WHHP050T45MD240S**** if you need more hot water in your busiest hour: it lists a first hour rating of 69 gallons against 67.
  • Neither if your household's busiest hour needs more than 69 gallons of hot water — neither lists more. Check whether a 40-gallon heater is enough.

Each model on its own

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