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    A.O. Smith Tankless Water Heater Reviews

    Tankless Geek currently reviews 2 A.O. Smith models. Each review separates our editorial score from Amazon customer ratings and links the source documents used for specifications, installation and warranty details.

    Specifications verified on the date shown in each review. Product availability and documents can change.

    A.O. Smith ATI-540H-N
    MID-RANGE
    Mid-Range

    A.O. Smith ATI-540H-N

    4.3

    High-output condensing natural-gas tankless (A.O. Smith ProLine XE) delivering 199,000 BTU/h and up to 10 GPM at roughly 0.93 UEF, with a copper heat exchanger, Ultra-Low NOx emissions, and recirculation capability for heavy-residential and light-commercial use.

    Amazon customer rating as of the last specification review. Not the Tankless Geek editorial score.

    Flow Rate:Up to 10 GPM
    Energy Type:Natural Gas
    Installation:Indoor
    Best For:Small to medium homes, Replacement applications, Budget conscious
    $1099
    A.O. Smith Signature 6.6 GPM
    PREMIUM
    Premium

    A.O. Smith Signature 6.6 GPM

    4.2

    Premium condensing gas tankless from A.O. Smith featuring advanced efficiency and reliable performance. This high-efficiency unit delivers excellent capacity with condensing technology for reduced operating costs.

    Amazon customer rating as of the last specification review. Not the Tankless Geek editorial score.

    Flow Rate:6.6 GPM
    Energy Type:Natural Gas
    Installation:Indoor
    Best For:Medium to large homes, High efficiency, Replacement applications
    $1299

    How to compare A.O. Smith models

    Compare usable flow at your required temperature rise, energy input, installation requirements, efficiency, service access and written warranty. A maximum GPM value without its test conditions is not enough to size a system.

    Sizing guideDownload the specification dataset