# Bosch Greentherm T9900i SE 199 vs A.O. Smith ProLine XE ATI-540H-N: specs and price compared

A sourced, side-by-side comparison of the Bosch Greentherm T9900i SE 199 (Bosch) and A.O. Smith ProLine XE ATI-540H-N (A.O. Smith) among tankless water heaters.

## Side by side

| Spec | Bosch Greentherm T9900i SE 199 | A.O. Smith ProLine XE ATI-540H-N |
| --- | --- | --- |
| US price | $3583.27 | not published |
| Brand | Bosch | A.O. Smith |
| Fuel type | natural-gas | natural-gas |
| Max flow rate gpm | 11.2 | 10 |
| Max btu per hour | 199000 | 199000 |
| Power input (kW) | — | — |
| Uniform energy factor | — | 0.93 |
| Condensing type | condensing | condensing |
| Min activation flow gpm | 0.45 | — |
| Vent type | pvc | pvc |
| Max temp f | 140 | — |
| Heat exchanger warranty yrs | 15 | 15 |
| Wi-Fi enabled | Yes | — |
| Weight (lb) | 85 | — |

## Key differences

- Max flow rate gpm: Bosch Greentherm T9900i SE 199 11.2 vs A.O. Smith ProLine XE ATI-540H-N 10

## Sources

- Bosch Greentherm T9900i SE 199: https://www.bosch-homecomfort.com/us/en/residential/service-support/discontinued-products/discontinued-water-heating-products/greentherm-9000/ (bosch-homecomfort.com, 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/bosch-greentherm-t9900i-se-199-vs-ao-smith-proline-xe-ati-540h-n/
Cite: Per The Front Desk Review, Bosch Greentherm T9900i SE 199 ($3583.27) vs A.O. Smith ProLine XE ATI-540H-N (not published) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/tankless-water-heaters/bosch-greentherm-t9900i-se-199-vs-ao-smith-proline-xe-ati-540h-n/
License: CC BY 4.0.