TankBirthday

Water Heater Serial Number Lookup: Free Decoder by Brand

Not sure which brand made your tank? Enter the brand name from the plate in the lookup on any brand page — the “Not sure?” box maps store labels like Kenmore, State, and Ruud to their manufacturer.

Which Water Heater Brand Is Your Serial From?

Most people searching "water heater serial number lookup" have the serial in hand but not the brand knowledge — and every manufacturer encodes the date differently. This page solves exactly that: paste the serial and it identifies the format for you.

How it works: the detector above runs your serial against every decoder on this site at once:

  • Rheem (plus Ruud, Richmond, GE, and other Rheem-built labels) — month + year digits after a letter prefix
  • A.O. Smith (plus State, Reliance, American, Kenmore in most eras) — year + week digits
  • Bradford White — two-letter code with a 20-year repeating cycle
  • Navien, Rinnai, Bosch (tankless) — each with its own date-code scheme

When it matches, you get the decoded date immediately plus a link to the brand's full page, where the same serial is decoded with worked examples and warranty context. When it can't match, it tells you what to check instead of guessing.

Why a Serial Lookup Beats the Alternatives

  • Receipts lie — a tank can sit in distribution for months after the manufacture date, and warranties run from the date of manufacture, not installation.
  • Model numbers don't encode dates — only the serial does.
  • Every brand hides the date differently — Rheem puts the month first, A.O. Smith puts the year first, Bradford White uses letters that repeat every 20 years. The same-looking serial decodes differently by brand, which is exactly why the detector above exists.

What You Get After Decoding

Once you know the manufacture date: the tank's age against the typical 8–12 year service life, whether a warranty claim is still possible (most warranties run 6–12 years from the manufacture date), and how urgently to plan a replacement. A 14-year-old tank is days from a $1,600–$3,000 replacement decision — knowing the date lets you make it calmly instead of during an emergency.

Sources

Serial formats on this page are compiled from our own decoder implementations, each verified against manufacturer and industry references: the InterNACHI water heater dating chart, Rheem's guide to reading serial numbers, A.O. Smith's production-date guidance, and Bradford White's serial-number guidance.

Frequently asked questions

How do I look up a water heater by serial number?
Enter the serial number from the rating plate (the silver sticker on the side of the tank) in the detector above. It runs the serial against every brand format on this site — Rheem, A.O. Smith, Bradford White, Navien, Rinnai, and Bosch — and shows you which one matches, with the decoded manufacture date and a link to that brand's full lookup page.
What do water heater serial numbers look like?
Rheem-built units (Ruud, Richmond, GE, and other labels) open with digits that mean month + year, often after a letter prefix — RH0806B17262 is August 2006. A.O. Smith-built units (State, Reliance, American, Kenmore in most eras) put year + week in the first four digits — 1914B000123 is week 14 of 2019. Bradford White uses two letters (year on a 20-year cycle, then month). Tankless brands differ again: Navien embeds the date mid-serial, Rinnai leads with year/month letters (2009+) or digits, and Bosch uses a three-digit code or digits 5–7.
Why does my serial number match two brands?
Letter-based formats can overlap — for example, a serial starting with two letters could be a Bradford White code or a Rinnai code depending on length and the characters used. When that happens the detector honestly lists every match with its decoded result; check the brand name on the rating plate to pick the right one.
Can I find the age from the model number instead?
No. The model number describes the product line — capacity, fuel type, and feature tier — not when the unit was built. The manufacture date is encoded in the serial number, which is unique to your unit.
My serial did not match any format. What now?
First double-check the characters — 0/O, 1/I/l, and 8/B are easy to mix up on a worn sticker. Then look at the brand name on the plate: if it is a store label like Kenmore, State, or Ruud, open that brand's page directly (the "Not sure?" box on every lookup maps labels to manufacturers). Some very old formats are intentionally not auto-detected; those pages list the era caveats.