A.O. Smith Water Heater Age Lookup
A.O. Smith uses one consistent date code across ProLine, Vertex, Voltex, and its commercial lines. Enter any A.O. Smith serial number to get the precise build date and current age in seconds. Handy for spotting an aging tank before it fails.
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Finding Your A.O. Smith Serial Number
Check these four spots on your A.O. Smith water heater
Common Locations
What to Look For
- White or metallic manufacturer sticker
- Labeled "Serial No." or "S/N"
- Typically 8–12 characters long
- Usually near the model number
Can't find it? Try removing access panels or checking behind the temperature dial.
A.O. Smith Serial Number Examples
Don't worry if yours looks different - A.O. Smith has multiple formats and our system can decode most variations.
About A.O. Smith Water Heaters
A.O. Smith water heaters represent over 150 years of American manufacturing excellence, dating back to 1874 when the company began operations in Milwaukee, Wisconsin. Today, A.O. Smith stands as North America's largest manufacturer of residential and commercial water heating equipment, serving millions of homes and businesses. The company operates under multiple respected brands and maintains a reputation for engineering innovation and quality construction that has made their products a top choice for professional installers and homeowners alike.
A.O. Smith water heaters span an impressive range of technologies including traditional tank-style gas and electric models, high-efficiency condensing units, tankless systems, and cutting-edge hybrid heat pump models. Their Vertex line delivers up to 96% thermal efficiency for commercial applications, while the Signature Premier series offers residential customers advanced features like electronic ignition and self-diagnostic systems. Many models carry ENERGY STAR certification and feature industry-leading warranties, with premium residential units backed by up to 12-year tank coverage. The company invests heavily in corrosion-resistant materials, including their proprietary Blue Diamond glass coating and commercial-grade anode rods.
Owners of A.O. Smith water heaters benefit from extensive parts availability through a nationwide network of authorized dealers and service centers. The company provides detailed installation manuals, troubleshooting guides, and online warranty registration tools that simplify maintenance and service needs. Professional contractors appreciate A.O. Smith's consistent serial number formatting and model nomenclature, which clearly indicates manufacturing dates, capacity specifications, and fuel types. Customer support includes technical assistance lines staffed by trained specialists who can help diagnose issues and locate qualified service providers in your area.
Where to find the serial
Look at the rating plate on the upper third of the tank, usually a silver foil sticker near the cold inlet pipe. The serial sits below the model number and is labeled SERIAL or SER. NO. On commercial units the label is often on the side panel. A.O. Smith uses tall narrow stickers that tend to fade in attics, so a phone flashlight helps.
What the serial actually looks like
Why the age is worth knowing
A.O. Smith residential warranties typically run 6, 9, or 12 years on the tank depending on the line (ProLine, ProLine XE, Signature Premier). Commercial Cyclone and Vertex units have shorter coverage but longer expected service life. After year 10 on a residential tank, budget for replacement even if it still works.
Quick answers for this brand
Is A.O. Smith the same company as State and American Water Heater?
Yes, A.O. Smith Corporation owns State Industries and American Water Heater Company, and the three brands share manufacturing plants in Ashland City TN, McBee SC, and Johnson City TN. The serial number formats are nearly identical across all three brands.
What's the difference between an A.O. Smith ProLine and Signature?
ProLine is the contractor-only line sold through plumbing wholesalers, while Signature and Signature Premier are sold at Lowe's. The internal components are similar but warranty terms and a few features differ. Both decode the same way from the serial.
Where is the date code on a Vertex commercial A.O. Smith?
Commercial Vertex units use the same YYWW format in the first four digits of the serial, but the rating plate is on the side or back panel instead of the top. The serial may also include a leading letter for the plant code.
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