DoesTheMath

Noritz EZ98DV (GQ-C2859WX-FF US) vs Ruud RTGH-S10I: which uses less energy?

At the high draw pattern the Noritz EZ98DV (GQ-C2859WX-FF US) and the Ruud RTGH-S10I use the same energy, 176 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
Noritz EZ98DV (GQ-C2859WX-FF US) Ruud RTGH-S10I
UEF (Uniform Energy Factor) 0.96 0.96
Energy use per year (therms) 176 176
Max flow (GPM) 5.3 5.2
Installed cost range $2,405–$3,460 $2,405–$3,460
ENERGY STAR certified yes yes
On the market since 2017-05-01 2022-08-01
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.
  • 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 Noritz EZ98DV (GQ-C2859WX-FF US) since 2017-05-01, the Ruud RTGH-S10I since 2022-08-01. A sale date, not a lifespan.

Which should you pick?

  • Pick the Noritz EZ98DV (GQ-C2859WX-FF US) if its price or availability suits you — on energy the two are level.
  • Pick the Ruud RTGH-S10I if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Noritz EZ98DV (GQ-C2859WX-FF US).
  • Neither if you need more than 5.3 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.

Each model on its own

Analytics cookies

We count page views without cookies for everyone, and that counter is what we use to decide what to build. Google Analytics is separate: it uses cookies to record how a page was used, and it loads only if you allow it. Decline and the site works exactly the same. What we collect.