DoesTheMath

Richmond RTGH-S84I vs RINNAI (RX160I) REU-NB2530FF-US: which uses less energy?

At the high draw pattern the RINNAI (RX160I) REU-NB2530FF-US uses 175 therms a year and the Richmond RTGH-S84I 176 — 2 therms (1%) less, about 18 therms over ten years. Both are filed as a gas tankless unit, so the comparison holds. Enter your ZIP below to price the difference.

Side by side

Compared within one class only: models filed as a gas tankless unit at the high draw pattern.

Filed and computed figures
Richmond RTGH-S84I RINNAI (RX160I) REU-NB2530FF-US
UEF (Uniform Energy Factor) 0.96 0.97 (better)
Energy use per year (therms) 176 175 (better)
Max flow (GPM) 4.6 4.6
Installed cost range $2,405–$3,460 $2,452–$3,515
ENERGY STAR certified yes yes
On the market since 2024-09-01 2024-03-01
DOE CCD · 2026-09-19

What it costs to run

Richmond RTGH-S84I: 176 therms a year RINNAI (RX160I) REU-NB2530FF-US: 175 therms a year

Richmond RTGH-S84I — 176 therms a year RINNAI (RX160I) REU-NB2530FF-US — 175 therms a year

RINNAI (RX160I) REU-NB2530FF-US is 1 therms a year lower than Richmond RTGH-S84I.

DOE CCD · 2026-09-19

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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.
  • Both are ENERGY STAR certified, which requires a manufacturer warranty of at least six years; the actual term for each model is not published.
  • Time on the market, as filed with ENERGY STAR: the Richmond RTGH-S84I since 2024-09-01, the RINNAI (RX160I) REU-NB2530FF-US since 2024-03-01. A sale date, not a lifespan.

Which should you pick?

  • Pick the RINNAI (RX160I) REU-NB2530FF-US if running cost matters most: it uses 2 therms less a year on the same test.
  • Pick the Richmond RTGH-S84I if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the RINNAI (RX160I) REU-NB2530FF-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

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