How Old Is My AO Smith Water Heater – Find Out Here!

My AO Smith water heater recently developed some issues. When I contacted the installation and repair company, they immediately asked for the AO Smith water heater date code because it shows the age of the AO smith water heater.

You can find how old your AO Smith water heater is from the serial numbers. In heaters built before 2008, the four numbers after the first letter show the year and month. For heaters made post-2008, the first two digits represent the year, while the third and fourth digits indicate the week.

I’ll discuss the AO Smith water heaters model numbers and how to interpret the various series numbers to tell the age of your heater. 

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Ways To Tell the Age of an AO Smith Water Heater

“How can I tell how old my ao smith water heater is?” is one of the questions I had after discovering the type and make of the heater in the home I had just bought. I needed to know how soon I should expect to replace it because the house was old. 

The AO Smith water heater date code is evident in the first four numbers on the serial number. In water heaters manufactured before 2008, the first two numbers tell the year, while the next two represent the month. In heaters manufactured after 2008, the third and fourth digits show the week instead of the month.

For example, serial number U0205413334, the first four numbers (0205) show the water heater was made in May 2002. 

If the heater’s first two numbers are 08, 09, and above, then the following two digits represent the week. For example, if the first four numbers are 1125, the heater was made in the 25th week of the year 2011. 

Finding the Manufacture Date on AO Smith Water Heater

The manufacture date of AO Smith water heater is in the serial number. Unfortunately, AO Smith has been changing the format of the serial numbers over the years, so you need to understand the style to interpret the manufacture date correctly. 

For example, AO Smith water heaters made before 2008 have serial numbers representing the year and month (the first four numbers). 

water heater plumber

The format changed slightly for heaters made in subsequent years. The recent serial numbers follow a different format from older models. 

You can only determine the manufacture date of ao smith water heater if you understand the serial number formats

Style 1

Style 1 had three main formats. 

  • Style 1a – 1214A001143. The first two digits (12) show the year (2012), while the next two digits (14) represent the week the AO water heater was manufactured. 
  • Style 1b – S1412F000036. Like style 1a, the first two numbers represent the years, while the next two show the week. The first letter has no bearing on the age of AO Smith water heater.
  • Style 1c – 1830111872341. This format is like 1a and 1b. It shows the heater was manufactured on the 30th week of 2018. 

Style 2 – AH03A092001

Codes representing months on AO Smith water heaters

The first letter represents the factory code (A). The second letter represents the month (August), while the first two numbers show the year (2003). 

In July 2004, the factory code was discontinued. Models made before 2004 had factory codes A, M, and G, while those made after 2004 don’t have the factory code. 

Style 3 – GG02 – 13495065 – S28

This serial number format is another you may encounter when checking what year is my AO Smith water heater. It is similar to style 2, except for the serial numbers’ length and dashes. The first letter is the factory code. However, like style 2, this code was dropped in 2004.

Style 4 – D07A142090

The first letter in this format represents the month (April). The following numbers represent the year (07). This serial number format on AO Smith water heater was last used in 2008 models.

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Where Is Serial Number on AO Smith Water Heater?

You can tell the AO Smith water heater age by the serial number. To find out the age, you first need to find the serial number location on AO Smith water heater. 

The serial number on AO Smith water heater is on the label close to the bottom of the water heater. The label has information on the water heater, including the serial number, approved use, model number, part number, and wattage. It also shows the capacity, circuit, and working pressure.

The serial number location on AO Smith water heater is critical because you get all the information you need about the heater. When reporting a fault or buying parts for the heater, you will need to know how to tell AO Smith water heater age.

This video shows where to find the serial number and read the age of your AO Smith water heater.

How Long Should AO Smith Water Heaters Last?

One of the things you should seek to know when moving to a new home or when buying property is how long fixed appliances have been in use. This way, you can find age of AO Smith water heater and how long it has been in use.

AO Smith water heaters should last for 6 – 10 years. This is how long the limited warranty lasts, depending on the type of water heater. However, some water heaters last for more than a decade, depending on how well they are maintained. It is best to replace water heaters before the 15th year. 

small water heater

The AO Smith water heater age by serial number is accurate and allows you to understand more about the heater. Even though the warranty is not transferable, you can plan on maintenance and possibly budget for a replacement when necessary. 


The serial number AO Smith water heater tells you when it was manufactured. These numbers also tell you the model of your heater, so you’ll also know if it is among those recalled for one issue or another. Should it develop issues, the maintenance company will also know what they need and the right parts for the water heater.