Best Tankless Water Heaters · head-to-head

Navien NPE-240A2 vs A.O. Smith ProLine XE ATI-540H-N

A sourced, side-by-side comparison. Navien NPE-240A2 is cheaper at $2099. Every spec and price links to its source.

Full spec sheet

marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.

Spec Navien NPE-240A2 A.O. Smith ProLine XE ATI-540H-N
US price $2099
BrandNavienA.O. Smith
Released
Fuel type natural-gas natural-gas
Max flow rate gpm 11.2 10
Max btu per hour 199900 199000
Power input (kW)
Uniform energy factor 0.95 0.93
Condensing type condensing condensing
Min activation flow gpm 0.5
Vent type pvc pvc
Max temp f
Heat exchanger warranty yrs 15 15
Wi-Fi enabled No
Weight (lb) 77

Sources — Navien NPE-240A2: navieninc.com (verified 2026-07-11). A.O. Smith ProLine XE ATI-540H-N: hotwater.com (verified 2026-07-11).

What's the difference between the Navien NPE-240A2 and A.O. Smith ProLine XE ATI-540H-N?

Where the two actually differ on the specs we track (3 of 12). Matching specs are omitted.

  • Max flow rate gpm: Navien NPE-240A2 11.2 vs A.O. Smith ProLine XE ATI-540H-N 10
  • Max btu per hour: Navien NPE-240A2 199900 vs A.O. Smith ProLine XE ATI-540H-N 199000
  • Uniform energy factor: Navien NPE-240A2 0.95 vs A.O. Smith ProLine XE ATI-540H-N 0.93

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