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)Tand 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.