DoesTheMath

HEAT-FLO SSL-20S vs Rheem PROE36 S2 RH95: which uses less energy?

At the low draw pattern the HEAT-FLO SSL-20S and the Rheem PROE36 S2 RH95 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.

Filed and computed figures
Figure HEAT-FLO SSL-20S Rheem PROE36 S2 RH95
UEF (Uniform Energy Factor) 0.92 0.92
Energy use per year (kWh) 2,439 2,439
First hour rating (gal) 33 34
Rated storage volume (gal) 23 33
Installed cost range not published $1,548–$1,727
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

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.
  • The actual warranty term is printed in each model’s documentation, not in any registry.

Which should you pick?

  • Pick the HEAT-FLO SSL-20S if its price or availability suits you — on energy the two are level.
  • Pick the Rheem PROE36 S2 RH95 if you need more hot water in your busiest hour: it lists a first hour rating of 34 gallons against 33.
  • Neither if your household's busiest hour needs more than 34 gallons of hot water — neither lists more.

Each model on its own