Residential & Commercial Water Heaters
How Old Is My A.O. Smith?
Type the serial number from the rating label on your A.O. Smith water heater to see when it was made and how much of its typical 10-year life is left.
Try an example:
Where to find the serial number on a A.O. Smith
On a tank water heater, the rating label is on the side of the tank, usually near the gas valve or the upper electrical cover. Look for "SERIAL NO." or "S/N".
Tip: in a dark basement or closet, take a photo of the label with your phone's flash on and zoom in on the photo.
How to read a A.O. Smith serial number
Year + week (modern)
Used 2004–today
Digits 1-2 are the year and digits 3-4 are the week of the year (01-52).
Example: 1832104562 → August 2018 (week 32)
Month letter + year (before 2004)
Used 1970–2004 · varies between models, confirm with the label date
The first letter is the month (A = January ... H = August, J = September ... M = December; I is skipped). The next 2 digits are the year. F98 = June 1998.
Example: F98-123456 → June 1998
Common replacement parts for A.O. Smith
Always match the part to the model number on your rating label, and have gas or refrigerant work done by a licensed technician.
- A.O. Smith 100108683 Silicon Nitride Hot Surface IgniterCheck price on Amazon
- A.O. Smith 9003974005 Aluminum Flexible Sacrificial Anode RodCheck price on Amazon
Cheap ways to avoid water damage
Water leak alarm
Sits on the floor next to the tank and sounds a siren at the first drop of water.
See leak alarms on AmazonWater heater drain pan
Catches small leaks and can be piped to a drain, which buys you time before a tank fails.
See drain pans on Amazon
Common questions about A.O. Smith equipment
Where is the serial number located on an A.O. Smith water heater?
A.O. Smith displays the serial number on the large rating plate sticker located about halfway up the tank shell, near the plumbing hookups and EnergyGuide label.
Does A.O. Smith manufacture other water heater brands?
Yes, A.O. Smith manufactures water heaters under several major brand names including State, Reliance, American Water Heaters, Whirlpool, and Lochinvar. Most share the standard YYWW serial coding.
How long does a A.O. Smith water heater last?
About 10 years on average. Units that get yearly maintenance often last longer; units in hard-water areas, coastal air or unconditioned spaces often fail sooner.
Is the serial number the same as the model number?
No. The model number describes the product line, size and options. The serial number identifies your exact unit and contains the manufacture date. Both are printed on the same rating label.
How accurate is this age estimate?
The date comes from the published serial number formats for each brand. It is the factory date, not the installation date, and some formats repeat every 10 or 20 years. If the label shows a printed MFG. DATE, that date wins.