Kepler JSG48-29PCH/180K vs Ruud RTGH-S10I: which uses less energy?
At the high draw pattern the Ruud RTGH-S10I uses 176 therms a year and the Kepler JSG48-29PCH/180K 178 — 2 therms (1%) less, about 19 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.
| Figure | Kepler JSG48-29PCH/180K | Ruud RTGH-S10I |
|---|---|---|
| UEF (Uniform Energy Factor) | 0.95 | 0.96 (better) |
| Energy use per year (therms) | 178 | 176 (better) |
| Max flow (GPM) | 5.2 | 5.2 |
| Installed cost range | $2,358–$3,405 | $2,405–$3,460 |
| ENERGY STAR certified | yes | yes |
| On the market since | 2024-05-30 | 2022-08-01 |
What it costs to run
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 Kepler JSG48-29PCH/180K since 2024-05-30, the Ruud RTGH-S10I since 2022-08-01. A sale date, not a lifespan.
Which should you pick?
- Pick the Ruud RTGH-S10I if running cost matters most: it uses 2 therms less a year on the same test.
- Pick the Kepler JSG48-29PCH/180K if it is the one you can get installed sooner or for less — on the filed figures it has no advantage over the Ruud RTGH-S10I.
- Neither if you need more than 5.2 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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Kepler JSG48-29PCH/180K
Its filed figures, class position and running cost on your ZIP.
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Ruud RTGH-S10I
Its filed figures, class position and running cost on your ZIP.