John Wood Water Heater Age by Serial Number — Free Lookup

How Old Is Your John Wood Water Heater?

John Wood is a Canadian water heater brand owned by A.O. Smith, so its serial numbers carry the same date code as GSW, State, Reliance, and American units: year, then week, in the first four digits. Enter your serial in the free decoder above for an instant answer, or follow the guide below to read it yourself.

Where to Find the Serial Number

Check the rating plate on the side of the tank — a silver or white sticker, usually in the upper half, that lists the model number and serial number together. The date lives in the serial, not the model number. On older tanks the sticker can fade; a phone photo with the contrast bumped usually makes the first four digits readable.

How the John Wood Serial Format Works

The date code is year, then week, in the first four digits:

Worked example — 2011B006209:

• 20 = 2020 (year)
• 11 = week 11 (mid-March)
• B and the remaining digits = factory and production sequence
• Result: manufactured in week 11 of 2020

Letter prefixes. Some serials start with letters, or insert a letter inside the date block — these are factory or product-line codes, not part of the date. Skip leading letters and read the first four digits you find.

Because the year is two digits, a code like 20 could mean 2020 on a recent unit — and the same digits appear in older cycles. Compare the unit's condition and model line; our decoder lists every plausible year instead of guessing.

Why Your John Wood Water Heater's Age Matters

• Lifespan. Tank water heaters average 8–12 years of service. Past that, internal corrosion makes tank failure — and a flooded basement — far more likely.
• Warranty. John Wood tanks carry standard 6- and 12-year warranty tiers counted from the manufacture date, not the install date. The serial tells you whether a repair might still be covered.
• Replacement planning. A unit past 10 years is on borrowed time. Knowing the date lets you shop for a replacement calmly instead of during an emergency.

Sources

Brand ownership verified against A.O. Smith's corporate history and the InterNACHI water heater dating chart; serial format follows A.O. Smith's manufacturing-date guidance.