DoesTheMath

Noritz NRC98OD (GQ-C2857WS US) vs RELIANCE WATER HEATERS T-H3S-OS-N 1**: which uses less energy?

At the high draw pattern the RELIANCE WATER HEATERS T-H3S-OS-N 1** uses 180 therms a year and the Noritz NRC98OD (GQ-C2857WS US) 184 — 4 therms (2%) less, about 39 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
Noritz NRC98OD (GQ-C2857WS US) RELIANCE WATER HEATERS T-H3S-OS-N 1**
UEF (Uniform Energy Factor) 0.92 0.94 (better)
Energy use per year (therms) 184 180 (better)
Max flow (GPM) 5.2 5.3
Installed cost range $2,216–$3,239 $2,311–$3,350
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

Noritz NRC98OD (GQ-C2857WS US): 184 therms a year RELIANCE WATER HEATERS T-H3S-OS-N 1**: 180 therms a year

Noritz NRC98OD (GQ-C2857WS US) — 184 therms a year RELIANCE WATER HEATERS T-H3S-OS-N 1** — 180 therms a year

RELIANCE WATER HEATERS T-H3S-OS-N 1** is 4 therms a year lower than Noritz NRC98OD (GQ-C2857WS US).

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

Which should you pick?

  • Pick the RELIANCE WATER HEATERS T-H3S-OS-N 1** if running cost matters most: it uses 4 therms less a year on the same test.
  • Pick the Noritz NRC98OD (GQ-C2857WS US) if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the RELIANCE WATER HEATERS T-H3S-OS-N 1**.
  • 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

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