HEAT-FLO SSL-50D vs MARATHON MR50245 C: which uses less energy?
At the medium draw pattern the HEAT-FLO SSL-50D uses 3,531 kWh a year and the MARATHON MR50245 C 3,569 — 39 kWh (1%) less, about 388 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 | HEAT-FLO SSL-50D | MARATHON MR50245 C |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.92 (better) | 0.91 |
| Energy use per year (kWh) | 3,531 (better) | 3,569 |
| First hour rating (gal) | 54 | 57 |
| Rated storage volume (gal) | 51 | 50 |
| Installed cost range | $1,808–$2,178 | not published |
| ENERGY STAR certified | not matched | not matched |
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 below.
- The actual warranty term is printed in each model’s documentation, not in any registry.
Which should you pick?
- Pick the HEAT-FLO SSL-50D if running cost matters most: it uses 39 kWh less a year on the same test.
- Pick the MARATHON MR50245 C if you need more hot water in your busiest hour: it lists a first hour rating of 57 gallons against 54.
- Neither if your household's busiest hour needs more than 57 gallons of hot water — neither lists more. Check whether a 50-gallon heater is enough.
Each model on its own
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HEAT-FLO SSL-50D
Its filed figures, class position and running cost on your ZIP.
-
MARATHON MR50245 C
Its filed figures, class position and running cost on your ZIP.