DoesTheMath

Reservoir N51 vs Ruud PRO H65 T2 RH310BM: which uses less energy?

At the high draw pattern the Reservoir N51 uses 1,405 kWh a year and the Ruud PRO H65 T2 RH310BM 1,417 — 12 kWh (1%) less, about 120 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 high draw pattern.

Filed and computed figures
Figure Reservoir N51 Ruud PRO H65 T2 RH310BM
UEF (Uniform Energy Factor) 3.53 (better) 3.5
Energy use per year (kWh) 1,405 (better) 1,417
First hour rating (gal) 75 75
Rated storage volume (gal) 47 59
Installed cost range $3,064–$4,199 $3,449–$4,282
ENERGY STAR certified not matched yes
Refrigerant not filed R-134a, GWP 1430
On the market since not filed 2020-04-30
DOE CCD · 2026-09-19

What it costs to run

Reservoir N51: 1,405 kWh a year Ruud PRO H65 T2 RH310BM: 1,417 kWh a year

Reservoir N51 — 1,405 kWh a year Ruud PRO H65 T2 RH310BM — 1,417 kWh a year

Reservoir N51 is 12 kWh a year lower than Ruud PRO H65 T2 RH310BM.

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

Which should you pick?

  • Pick the Reservoir N51 if running cost matters most: it uses 12 kWh less a year on the same test.
  • Pick the Ruud PRO H65 T2 RH310BM if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Reservoir N51.
  • Neither if your household's busiest hour needs more than 75 gallons of hot water — neither lists more. Check whether a 50-gallon heater is enough.

Each model on its own