Whirlpool Water Heater Age: How to Read the Serial Number

Last updated: July 2026 · Based on Whirlpool water heater serial number conventions

To find the age of a Whirlpool water heater, look at the first four digits of the serial number on the rating plate. Whirlpool water heaters (built by American Water Heaters / A.O. Smith) use a YYWW format: the first two digits are the year and the next two are the week. A serial starting 1832 means it was built in the 32nd week of 2018. Here is how to decode it and why it matters.

Where to Find the Serial Number

The serial number is on the rating plate — a sticker on the side of the tank, usually toward the top. Whirlpool water heaters were sold through Lowe’s and are manufactured by American Water Heaters (part of A.O. Smith), which is why the dating format matches other A.O. Smith brands.

Decoding the Age (YYWW)

If the first four digits do not look like a plausible year/week (for example, a week number above 52), your unit may use an older or different code — check the rating plate for a separate manufacture date or contact the manufacturer with the full serial.

Why the Age Matters

• Under 6 years: the tank is likely still under warranty — check before paying for a replacement.
• 8–12 years: the normal end-of-life window for a tank heater; weigh repairs carefully.
• Over 12 years: any major fault usually means replace, not repair.

Age is the deciding factor when something goes wrong. A leaking water heater that is 10+ years old is almost always a replacement; a 4-year-old one with the same symptom is usually a cheap repair — and possibly a warranty claim.

Checking Your Whirlpool Warranty

Whirlpool water heater tank warranties typically run 6, 9, or 12 years depending on the model. Because these units were sold through Lowe’s and built by American Water Heaters, warranty claims may go through the manufacturer rather than the retailer. Have your serial number and model ready — if the unit failed within the warranty window, you may get a replacement tank at little or no cost.

FAQ

How do I tell the age of my Whirlpool water heater?

Read the first four digits of the serial number on the rating plate: the first two are the year, the next two the week of manufacture. “1832” means the 32nd week of 2018.

Who makes Whirlpool water heaters?

Whirlpool-branded water heaters are manufactured by American Water Heaters, part of A.O. Smith, and were sold primarily through Lowe’s. That is why they share the same YYWW serial dating format as other A.O. Smith brands.

How long do Whirlpool water heaters last?

Like most tank water heaters, 8–12 years on average. Regular flushing and anode rod checks push it toward the higher end; hard water and no maintenance shorten it.