# Rinnai RU199iN vs A.O. Smith ProLine XE ATI-540H-N: specs and price compared

A sourced, side-by-side comparison of the Rinnai RU199iN (Rinnai) and A.O. Smith ProLine XE ATI-540H-N (A.O. Smith) among tankless water heaters.

## Side by side

| Spec | Rinnai RU199iN | A.O. Smith ProLine XE ATI-540H-N |
| --- | --- | --- |
| US price | not published | not published |
| Brand | Rinnai | A.O. Smith |
| 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 | — |

## Key differences

- 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

## Sources

- Rinnai RU199iN: https://www.rinnai.us/residential/product-detail/ru199in (rinnai.us, verified 2026-07-11)
- A.O. Smith ProLine XE ATI-540H-N: https://www.hotwater.com/products/tankless-high-efficiency-condensing-proline-xe/ati-540h-100/100123378.html (hotwater.com, verified 2026-07-11)

Canonical: https://frontdeskreview.com/gear/tankless-water-heaters/rinnai-ru199in-vs-ao-smith-proline-xe-ati-540h-n/
Cite: Per The Front Desk Review, Rinnai RU199iN (not published) vs A.O. Smith ProLine XE ATI-540H-N (not published) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/tankless-water-heaters/rinnai-ru199in-vs-ao-smith-proline-xe-ati-540h-n/
License: CC BY 4.0.