How old is my Kenmore water heater?

The rule

Take the first four digits of the serial number.

Fast Water Heater: "In practice Kenmore tanks came from the A.O. Smith side of the industry, so read them year-then-week like the group above. Units from roughly 2008 to 2018 follow that rule; older ones use a letter for the month followed by the year."

So a serial beginning 1512 is week 12 of 2015, around late March. A serial beginning with a letter is an older unit, and the letter is the month on the A to M scale with I left out.

Two references, same conclusion

This matters because the opposite claim is widespread, including on this site until recently.

• InspectApedia's brand index: "Kenmore Water Heaters - see either AO SMITH WATER or STATE WATER." Rheem is not offered as an option.
• InspectApedia's State page lists the badges State Industries produced, and Kenmore and Sears both appear on it, alongside Ace, Reliance, Nationaline, Thermo-king and twenty more.
• Fast Water Heater places Kenmore on the A.O. Smith side explicitly.

The 153 prefix is a red herring

Fast Water Heater, on the model number: "Kenmore is a rebadge, and the model prefix does not tell you who built it. Every Kenmore water heater model starts with 153, because that is simply Sears' category code."

Read that twice, because the logic is what matters. If every Kenmore model begins with 153, then 153 cannot distinguish one manufacturer from another. Any rule of the form "if the model starts with 153 it was built by X" classifies every Kenmore as X, which is not a rule at all.

Our own error, and what it cost

We are not describing a hypothetical. Until 8 October 2026 our age decoder carried exactly that broken rule: a model starting 153 was treated as a Rheem and the serial was read month first.

What that produced, worked through:

More than seven years, and in the direction that makes an old tank look young. That is the direction that does real harm, because it is what tips a repair-or-replace decision the wrong way on a tank near the end of its life. Fast Water Heater flags the same magnitude for the general month-first versus year-first mix-up: "seven years apart."

We fixed the decoder, the tool now applies the year-week rule to Kenmore, and we left a dated correction notice on that page so anyone who used it before can re-check. This page exists partly so the correct answer has a permanent home rather than a footnote.

Nothing newer than 2018

Fast Water Heater: "Kenmore water heaters were discontinued around 2018, so nothing new is being built."

Our conclusion, marked as ours: that single fact settles most Kenmore questions without any decoding. The youngest Kenmore tank in service is around eight years old, which puts every one of them inside or past the usual 8 to 12 year failure window for a storage heater. If yours is working, it is living on borrowed time, and worth budgeting for rather than being surprised by, which is what the lifetime cost page is for; if it needs a repair, the arithmetic on the repair or replace page will almost always point at replacement.

Parts are the other half of that. A discontinued badge from a factory that built under many names means you are sourcing elements, thermostats and dip tubes by specification rather than by brand.

Related brands

Same factories, same rules: A.O. Smith, State, American and Whirlpool. The State page documents a real disagreement between the references on the four-digit order, which is worth reading if your Kenmore plate predates 2008.