Water heaters

How old is my State water heater?

State was bought by A.O. Smith in 2001 and now uses A.O. Smith's year-and-week serial. Tanks from before about 2008 used a month letter followed by the two-digit year, and before July 2004 a factory letter came first.

How to read a State serial number

Year and week (current (A.O. Smith owned State from 2001))

The first two digits are the year and the next two are the week of that year. An S in front is a factory code and is ignored.

1735107397129 reads as week 35 of 2017.

Two sources agree Building Intelligence Center, InterNACHI water heater dating chart

Month letter, then the year (older)

The first letter is the month (A is January, M is December, I is skipped). The two digits after it are the year.

M07A009387 reads as December 2007.

On units from the 1990s one source says State used fiscal-year month letters (A for October), so the month could be about three months off. The year is reliable.

Two sources agree Building Intelligence Center, InterNACHI water heater dating chart, Working RE

Factory letter, month letter, then the year (older, ended July 2004)

The first letter is the factory. The second letter is the month. The two digits after it are the year.

AF04A093001 reads as June 2004.

One source Building Intelligence Center

Where to find the serial number

Water heater: the rating label on the side of the tank, near the EnergyGuide sticker. On a tankless unit it is on the side or bottom of the cabinet.
Use the line marked Serial No. or S/N, not the model number. If the plate prints a manufacture date, use that.

How long should it last?

Typical life of a tank water heater: 8 to 12 years

A standard tank water heater usually lasts 8 to 12 years. Some make it to 15 with soft water and a replaced anode rod; some fail at 7.

How long does a tank water heater last? · Should I replace my water heater? · DC Dept. of Energy & Environment, InterNACHI

Should I replace it?

Should I replace my water heater?

Other brands in this group

A.O. Smith · American Water Heater · U.S. Craftmaster · Bradford White · Reliance · Kenmore · Whirlpool · Rheem · Ruud · Richmond · GE · Marathon · Rinnai · Navien · Noritz · Takagi · Bosch (tankless water heater) · Lochinvar · GSW / John Wood · Paloma · HTP / Westinghouse / American Standard (water heaters) · Giant · EcoSmart / Eemax · Stiebel Eltron

Parts that help it last

Anode rod The sacrificial rod that rusts instead of the tank. Checking it every few years is the cheapest way to add life.
Flush kit A hose and fittings for draining sediment from the bottom of the tank once a year.
Expansion tank Soaks up pressure swings in a closed plumbing system. Ask a plumber whether yours needs one.
Leak alarm A small alarm that goes on the floor beside the heater and warns you before a slow leak becomes a flood.

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