DoesTheMath

ENVO WH-AZ03-180-LPI vs Ranein RH10K-LPG: which uses less energy?

At the high draw pattern the ENVO WH-AZ03-180-LPI uses 197 therms a year and the Ranein RH10K-LPG 206 — 10 therms (5%) less, about 96 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
Figure ENVO WH-AZ03-180-LPI Ranein RH10K-LPG
UEF (Uniform Energy Factor) 0.86 (better) 0.82
Energy use per year (therms) 197 (better) 206
Max flow (GPM) 4.3 4.3
Installed cost range $1,933–$2,908 $1,745–$2,687
ENERGY STAR certified not matched not matched
DOE CCD · 2026-09-19

What it costs to run

ENVO WH-AZ03-180-LPI: 197 therms a year Ranein RH10K-LPG: 206 therms a year

ENVO WH-AZ03-180-LPI — 197 therms a year Ranein RH10K-LPG — 206 therms a year

ENVO WH-AZ03-180-LPI is 9 therms a year lower than Ranein RH10K-LPG.

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 ENVO WH-AZ03-180-LPI if running cost matters most: it uses 10 therms less a year on the same test.
  • Pick the Ranein RH10K-LPG if the installed price matters more than the running cost: its modeled installed range is $1,745–$2,687 against $1,933–$2,908.
  • Neither if you need more than 4.3 GPM at the same time — neither unit lists more. Check how to size a tankless unit by GPM.

Each model on its own