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Whirlpool Water Heater Age by Serial Number — Free Lookup

A.O. Smith

Also works for A.O. Smith-built labels: State, Reliance, American, Whirlpool, U.S. Craftmaster, Kenmore, GSW and John Wood.

How Old Is Your Whirlpool Water Heater?

Whirlpool-branded water heaters were never built by Whirlpool itself — they were made by American Water Heater Company under a licensing deal and sold through Lowe's starting around 2000. American Water Heater later became part of A.O. Smith, so Whirlpool units use the A.O. Smith serial format: the manufacture date sits in the first digits of the serial. Enter your serial number in the free decoder above for an instant answer, or follow the guide below.

One thing to know up front: Whirlpool exited the water heater business in the mid-2010s, when Lowe's replaced the Whirlpool line with A.O. Smith-branded units. Every Whirlpool tank still in service is therefore at least a decade old — past the average tank lifespan — so dating yours is more than trivia.

Where to Find the Serial Number

Check the rating plate (data plate) on the side of the tank — a sticker, usually in the upper half of gas and electric tank models, listing the model and serial numbers together. On Whirlpool hybrid heat pump and tankless units, the plate is often on a side panel or behind the front cover.

How the Whirlpool Serial Format Works

The date code is year, then week, in the first four digits — the same scheme as A.O. Smith, State, Reliance, and American.

Worked example — 1104T403904:

  • 11 = 2011 (year)
  • 04 = week 4 (late January)
  • T and the remaining digits = factory and production sequence
  • Result: manufactured in week 4 of 2011

Watch for letter prefixes. Some serials insert letters — these are factory or product-line codes, not part of the date. Skip leading letters and read the first four digits. Because the year is two digits, a code like 04... could mean 2004; since all Whirlpool units predate the mid-2010s, the older reading is usually the right one. When in doubt, our decoder flags ambiguous cases instead of guessing.

Why Your Whirlpool Water Heater's Age Matters

  • Lifespan. Tank water heaters average 8–12 years. Since Whirlpool tanks left production around 2013–2015, yours is at or past that range — internal corrosion makes tank failure far more likely.
  • Warranty. Warranties ran 6 to 12 years from the manufacture date through the American Water Heater / A.O. Smith lineage. Decode the serial before assuming a repair is out of pocket.
  • Replacement planning. A Whirlpool unit today is on borrowed time. Knowing the exact date lets you shop for a replacement calmly instead of during an emergency flood.

Sources

Brand history verified by Plumbing & Mechanical's report on the American Water Heater–Whirlpool–Lowe's license agreement and the Building Intelligence Center's Whirlpool water heater age guide. The mid-2010s phase-out at Lowe's is documented by First Quality Plumbing and this plumbing trade forum thread on Lowe's switch to A.O. Smith. Serial format details verified against the InterNACHI water heater dating chart.

Frequently asked questions

Who made Whirlpool water heaters?
Whirlpool never built water heaters in its own factories. The units were manufactured by American Water Heater Company under a license agreement and sold through Lowe's, starting around 2000. American Water Heater later became part of A.O. Smith, which is why Whirlpool serials follow the A.O. Smith date format.
Does Whirlpool still sell water heaters?
No. Whirlpool-branded water heaters were phased out of the Lowe's lineup in the mid-2010s, when Lowe's switched to selling A.O. Smith-branded units. If your tank says Whirlpool, it was almost certainly manufactured before then — which makes checking its age especially worthwhile.
How do I tell the age of a Whirlpool water heater from the serial number?
The first two digits are the year and the next two are the week of manufacture. For example, serial 1104T403904 means week 4 of 2011 — late January 2011. Letters inside the serial are factory codes; read the date from the leading digits.
Where is the serial number on a Whirlpool water heater?
On the rating plate — a sticker on the side of the tank, usually in the upper half, that lists the model and serial numbers together. On Whirlpool heat pump and tankless models, the plate may be on a side panel or behind the front cover.
Can I still get warranty service on a Whirlpool water heater?
Possibly — warranty claims for Whirlpool-branded units are handled through the manufacturer lineage (American Water Heater / A.O. Smith), not Whirlpool's appliance division. Tank warranties typically ran 6 to 12 years from the manufacture date, so decoding the serial tells you whether coverage could still apply.