DoesTheMath

Rheem PRO+G55-50N RH59 vs Ruud PRO+G55-45U RH59 EC1*: which uses less energy?

At the high draw pattern the Rheem PRO+G55-50N RH59 and the Ruud PRO+G55-45U RH59 EC1* use the same energy, 273 therms a year each, on the same federal test. Both are filed as a gas 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 a gas tank at the high draw pattern.

Filed and computed figures
Figure Rheem PRO+G55-50N RH59 Ruud PRO+G55-45U RH59 EC1*
UEF (Uniform Energy Factor) 0.62 0.62
Energy use per year (therms) 273 273
First hour rating (gal) 91 99
Rated storage volume (gal) 55 55
Installed cost range $1,777–$3,088 $1,777–$3,088
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 Rheem PRO+G55-50N RH59 if its price or availability suits you — on energy the two are level.
  • Pick the Ruud PRO+G55-45U RH59 EC1* if you need more hot water in your busiest hour: it lists a first hour rating of 99 gallons against 91.
  • Neither if your household's busiest hour needs more than 99 gallons of hot water — neither lists more. Check whether a 50-gallon heater is enough.

Each model on its own