AO Smith ProLine Tankless 10 GPM Gas Water Heater

The AO Smith ProLine Tankless 10 GPM Gas Water Heater (ATI-540H-N) is AO Smith's condensing tankless flagship, designed to compete head-on with Rinnai RU199iN and Navien NPE-240A2 for the 4–5 person household premium tankless slot. 10.0 GPM peak flow, 199,000 BTU condensing burner, 0.96 UEF, 15-year heat exchanger warranty.

Headline specifications

• Type: indoor condensing tankless, natural gas (LP-convertible)
• Maximum flow rate: 10.0 GPM at 35°F rise
• BTU input: 11,000–199,000 BTU/h (modulating)
• Energy Factor (UEF): 0.96
• Min activation flow: 0.5 GPM
• Temperature range: 100°F – 140°F
• Venting: PVC/CPVC schedule 40 up to 100 ft
• Warranty: 15-year heat exchanger, 5-year parts
• Dimensions: 26" H × 19" W × 13" D
• WiFi: optional via iCOMM module (not built-in like Rinnai Sensei)

Who this model is for

4–5 person households with 2–3 bathrooms, peak demand of 2–3 simultaneous demand points, existing natural gas service with 3/4" line, long ownership horizon (8+ years). Buyers shopping AO Smith's plumber distributor channel rather than big-box.

For 3–4 person households, drop to the equivalent ATI lower-tier or pivot to Rinnai RU160iN. For households running tub fills + showers concurrently or 4+ bathrooms, even 10 GPM tops out — consider RU199iN dual-unit cascading.

Where it beats the alternatives

Vs Rinnai RU199iN ($1,645): AO Smith ~10.0 GPM vs Rinnai 11.1 GPM. Same UEF (0.96), same warranty class (15-year heat exchanger). Rinnai ships built-in Control-R 2.0 WiFi; AO Smith requires the optional iCOMM module. Service network: Rinnai stronger. AO Smith wins if your installer is an AO Smith distributor.

Vs Navien NPE-240A2 ($1,499): Navien 11.2 GPM, included ComfortFlow buffer eliminates cold-water sandwich. AO Smith pure-tankless without buffer. Navien wins on cold-water sandwich; AO Smith wins on service network depth.

Vs Rheem RTGH-95DVLN ($1,499): Rheem 9.5 GPM, 12-year warranty, EcoNet WiFi standard. AO Smith 10 GPM, 15-year warranty, optional WiFi. AO Smith wins on flow and warranty length.

Where it falls short

No built-in WiFi — the iCOMM module is an extra ~$150. Rinnai Sensei and Rheem ship WiFi standard.

Cold-water sandwich without buffer tank. Navien's ComfortFlow handles this natively; AO Smith requires recirculation loop ($300–$500) or buffer tank ($400–$700).

Lower brand awareness in tankless than Rinnai or Navien. Service network is real but smaller — verify a tankless-certified installer is in your area before committing.

3/4" gas line required. Hard-water descaling annual.

Install considerations

Verify 3/4" gas line capacity to 199,000 BTU. PVC/CPVC schedule 40 vent up to 100 ft, concentric or two-pipe. 120V outlet near install. Service valves needed for annual descaling. Permit typical.

Install cost: $1,200–$2,200 like-for-like tankless swap; $2,900–$4,800 tank-to-tankless conversion with gas/venting upgrades.

Maintenance

• Annual descaling required to maintain warranty — 60–90 min with descaling pump
• Inlet filter clean annually
• Firmware updates via iCOMM (if installed)
• Burner inspection every 3 years by tankless-certified technician

Bottom line

The AO Smith ProLine Tankless 10 GPM is the AO Smith plumber-channel answer to Rinnai's RU199iN and Navien's NPE-240A2. 10 GPM, 0.96 UEF, 15-year warranty. Matches the spec-leaders on flow and efficiency; trails on WiFi (extra module) and brand recognition. Right pick if your installer is AO Smith-network. For installer-neutral buyers, the Rinnai RU199iN is the safer default. Click through for live distributor pricing.