A.O. Smith ATO-540H-N 199,000 BTU ATI-540H Condensing Ultra-Low NOx Indoor Tankless Water Heater

Product Description

The A.O. SMITH ATO-540H-N is a condensing ultra-low NOx indoor tankless water heater. This unit uses up to 199,000 BTU/hr of natural gas to deliver an endless supply of hot water. It is highly efficient with a Uniform Energy Factor (UEF) of 0.93.

• Continuous flow rate up to 10.0 GPM
• Primary commercial-grade copper heat exchanger stabilizes outgoing water temperatures quicker
• Secondary heat exchanger is made of 316L Stainless Steel to protect against corrosion

Product Highlights

This A.O. Smith tankless water heater provides years of hot water through innovation and quality. It is a residential product built to commercial-grade standards.

Product Information

Standard Information

• Brand: A.O. SMITH
• Manufacturer Part Number: ATO-540H-N
• Country of Origin: US

Technical Specifications

• Product Type: Tankless Heater
• Installation Type: Indoor Only
• Type: Space Saving
• Fuel Type: Natural Gas
• BTU Input: 199,000
• BTU (Min): 15000
• Vent Type: Direct Vent
• Energy Factor: 0.93
• Gas Connection: 3/4"
• Water Connection: 3/4"
• Voltage: 120
• Application: Residential
• Max Flow (GPM): 10
• Inlet Gas Pressure: 4.0-10.5"W.C
• Depth (Inches): 11.25
• Width (Inches): 17.75
• Height (Inches): 23.625
• Flow Rate at 70F Temp Rise (GPM): 5.4
• Flow Rate at 40F Temp Rise (GPM): 9.5
• Flow Rate at 50F Temp Rise (GPM): 7.5
• Flow Rate at 60F Temp Rise (GPM): 6.3
• UEF: 0.95
• Maximum BTUs: 199,000
• Power Source: gas_powered
• Water Connection Location: Bottom
• Emissions: Ultra-Low NOx
• ASME Certified: No
• Digital Display: Yes
• ENERGY STAR Certified: Yes
• GPM (@67 F Temp Rise): 5.8 GPM
• Minimum BTUs: 15,000
• Product Tier: ProLine XE
• Side Loop: No
• Item Type: Water Heater
• Gallons: Tankless
• Water Heater Type: Residential/Commercial
• Venting: Power Direct Vent
• Venting Type: Power Direct Vent
• Energy Star: Yes
• Connection Size: 3/4"
• Activation GPM: 0.5
• Duct Size: 3" Round, 4" Round
• Maximum Flow Rate: 9.5 GPM
• Minimum Flow Rate: 4.9 GPM
• Minimum Gas Input: 15000
• Vent Maximum Run: 1200, 840 in.
• Water Pressure (Max): 150 PSI
• Water Pressure (Min): 15 PSI
• Gas Connection Type: 3/4" NPT
• Heating Technology: Condensing
• Indoor Installation: No
• Natural Gas Pressure (Max): 10.5
• Altitude Certification: 6000 ft.
• Amperage: 0.74
• Condensing: Yes
• Default Temperature: 122
• Approved for Commercial Use: Yes
• Certifications: AHRI, ANSI, CSA, NSF
• Collection: ProLine
• Low Lead Compliant: Yes
• Made in America: Yes
• Mobile Home Approved: No
• Outdoor Approved: Yes
• Product Variation: Whole House Water Heater
• SCAQMD Compliant: Yes
• Title 20 Compliant: Yes
• Special Feature: Air-Fuel ratio (AFR) sensor
• Material Type: Copper, Stainless Steel