Sign In to View Pricing & Availability
- Ultra-Low NOx gas tankless water heaters with condensing technology featuring an unprecedented 0.95 Energy Factor which lowers operating costs and is environmentally friendly.
Looking for model-specific repair or replacement parts? Enter the unit’s serial number into the A.O. Smith Parts Finder.
A.O. Smith® Tankless Water Heater, Series: ATI-540H, 199000 Btu/hr Heating, Natural Gas, 3/4 in NPT Gas Connection, Electronic Spark Ignition, Power Direct Vent, 3 in, 4 in Vent, Condensing/Non Condensing: Condensing, 10 gpm, 0.95, 3/4 in NPT Water Connection, 15 to 150 psi, Ultra Low NOx: Yes, Indoor/Outdoor: Indoor, 17-3/4 in W x 11-1/4 in D x 23-5/8 in H, Dual
- Ultra low NOx emissions
- Primary heat exchanger is constructed of a commercial grade copper that is more resilient to erosion
- Copper is 25x better at heat transfer than stainless steel thus stabilizing outgoing water temperatures quicken
- Secondary heat exchanger is made of type 316L stainless steel to protect against corrosion
- Air-fuel ratio (AFR) sensor, exhaust and water temperature safety control, overheat cut-off fuse
- Exhaust, 3 in PVC venting up to 70 ft or 4 in PVC venting up to 100 ft
- Provides flexible venting with PVC, CPVC or ABS pipe for intake and exhaust (solid core only)
- Category III or IV venting can be used
- Certified from sea level to 10100 ft elevation
- Indoor model - Built-in temperature controller and advanced diagnostics to simplify troubleshooting
- Commercial / Residential / DualDualEnergy Factor0.95Flow Rate10 gpmHeating Capacity199,000 BTU/hrIndoor / OutdoorIndoorUltra Low NOxYesVent Size3 in, 4 inVent TypePower DirectCondensing / Non-CondensingCondensingDimensions17-3/4 in W x 11-1/4 in D x 23-5/8 in HGas Connection3/4 in NPTIgnition TypeElectronic SparkManufacturerA.O. SmithManufacturer #100123378Pressure Rating15 to 150 psiSeriesATI-540HWater Connection3/4 in NPT