Rinnai
Rinnai RU199iN
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Best Tankless Water Heaters · head-to-head
Rinnai RU199iN vs A.O. Smith ProLine XE ATI-540H-N
A sourced, side-by-side comparison. Rinnai RU199iN is cheaper at —. Every spec and price links to its source.
A.O. Smith
A.O. Smith ProLine XE ATI-540H-N
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Full spec sheet
✓ marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.
| Spec |  Rinnai RU199iN |  A.O. Smith ProLine XE ATI-540H-N |
|---|---|---|
| US price | — | — |
| Brand | Rinnai | A.O. Smith |
| Released | — | — |
| Fuel type | natural-gas | natural-gas |
| Max flow rate (gpm) | 11 | 10 |
| Max btu per hour | 199000 | 199000 |
| Power input (kW) | — | — |
| Uniform energy factor | 0.95 | 0.93 |
| Condensing type | condensing | condensing |
| Min activation flow (gpm) | — | — |
| Vent type | — | pvc |
| Max temp (°F) | — | — |
| Heat exchanger warranty yrs | 15 | 15 |
| Wi-Fi enabled | No | — |
| Weight (lb) | 64 | — |
Sources — Rinnai RU199iN: rinnai.us (verified 2026-07-11). A.O. Smith ProLine XE ATI-540H-N: hotwater.com (verified 2026-07-11).
What's the difference between the Rinnai RU199iN and A.O. Smith ProLine XE ATI-540H-N?
Where the two actually differ on the specs we track (2 of 12). Matching specs are omitted.
- Max flow rate (gpm): Rinnai RU199iN 11 vs A.O. Smith ProLine XE ATI-540H-N 10
- Uniform energy factor: Rinnai RU199iN 0.95 vs A.O. Smith ProLine XE ATI-540H-N 0.93