DoesTheMath

RINNAI RE199I (REU-VE2737FFD-US) vs Ruud RTG-84DVLN-3: which uses less energy?

At the high draw pattern the RINNAI RE199I (REU-VE2737FFD-US) and the Ruud RTG-84DVLN-3 use the same energy, 206 therms a year each, on the same federal test. Both are filed as a gas tankless unit, 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 tankless unit at the high draw pattern.

Filed and computed figures
Figure RINNAI RE199I (REU-VE2737FFD-US) Ruud RTG-84DVLN-3
UEF (Uniform Energy Factor) 0.82 0.82
Energy use per year (therms) 206 206
Max flow (GPM) 4.6 4.5
Installed cost range $1,745–$2,687 $1,745–$2,687
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 RINNAI RE199I (REU-VE2737FFD-US) if its price or availability suits you — on energy the two are level.
  • Pick the Ruud RTG-84DVLN-3 if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the RINNAI RE199I (REU-VE2737FFD-US).
  • Neither if you need more than 4.6 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.

Each model on its own