ProLine® XE Ultra-Low NOx Outdoor 199,000 BTU Condensing Natural Gas Tankless Water Heater

Model ATO-540P-N 100
5 out of 5 Customer Rating
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Installation Type
Fuel Source
Maximum BTU's

  • ENERGY STAR® certified
  • Continuous flow rate up to 10.0 GPM
  • Integrated recirculation pump
  • Product Details
    • ENERGY STAR® certified
    • Continuous flow rate up to 10.0 GPM
    • Integrated recirculation pump
    • Primary commercial-grade copper heat exchanger is 25x better than stainless steel at heat transfer, stabilizing outgoing water temperatures quicker
    • Secondary heat exchanger is made of 316L Stainless Steel to protect against corrosion
    • Highly efficient condensing Ultra-Low Nox tankless water heater delivers up to .95 Uniform Energy Factor (UEF)
    • Common vent up to 8 units, Easy-Link 540P with three other 540H to increase flow capacity
    • Includes a wall mount temperature remote controller and advanced diagnostics to simplify troubleshooting
    • Safety features include exhaust & water temperature safety control, overheat cut-off fuse and air-fuel ratio (AFR) sensor
    • 15-year limited warranty on heat exchanger in residential applications

    • The 540P series integrates a recirculation pump to provide instant hot water in residential applications with dedicated recirculation lines. The pump is easily controlled with a simple user interface and multiple pump settings allow you to customize pump operation to meet your needs while maximizing heater efficiency. As part of the high efficiency tankless family, the 540P series provides endless hot water while being environmentally friendly. The ATO-540P-N outdoor tankless water heater uses up to 199,000 BTU/hr of natural gas to deliver an endless supply of hot water for a 3 bath home in northern climates and a 4 bath home in southern climates. It is built with commercial grade materials like marine-grade 316L stainless steel giving it an industry-leading warranty. A. O. Smith’s ProLine® water heaters are residential products built to commercial-grade standards and are only available for purchase through professional wholesalers and contractors.

    Tech Specs
    Maximum BTUs
    Power Source
    Limited Parts Warranty
    5 Years
    Water Connection Location
    ASME Certified
    Destination Country
    ENERGY STAR® Certified
    Fuel Source
    Installation Type
    Limited Heat Exchanger Warranty 
    15 Years
    Max Flow Rate
    Minimum BTUs
    Product Tier
    ProLine® XE
    Shipping Height 
    Shipping Length 
    Shipping Width 
    Side Loop
    Dimension & Venting
    Water Heater
    Shipping Weight
    Marketing Videos
    Take advantage of market incentives with ENERGY STAR® A.O. Smith water heaters
    All Reviews for ProLine® XE Tankless Condensing Integrated Recirculation Pump (100 series)
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