How old is my A.O. Smith unit?

A.O. Smith is part of A.O. Smith Corp. 4 serial formats sourced across water heater, tankless water heater, heat pump water heater.

• A.O. Smith water heater serial numbers in the 2008 to present format encode the year as digits 1-2 (YY) after optional leading S and the week as digits 3-4 (source: building-center.org).
• Example: serial 1210A002243 decodes to week 10 of 2012.
• A.O. Smith water heater serial numbers in the before 2010 format encode the year as digits 2-3 and the month as letter 1 (A=Jan..) (source: building-center.org).
• Example: serial E07A135491 decodes to May 2007.
• A.O. Smith water heater serial numbers in the before 2008 format encode the year as digits 3-4 and the month as letter 2 (A=Jan..) (source: building-center.org).
• Example: serial AF04A093001 decodes to June 2004.
• A.O. Smith's official lookup at hotwater.com returns warranty status.

Decoder pages by product

Format eras

• before 2010 VERIFIED
  A##A######Water Heater
• 2008 to present VERIFIED
  ####A######Water Heater, Heat Pump Water Heater, Tankless Water Heater
• before 2008 VERIFIED
  AA##A######Water Heater
• 1970 to 1979 VERIFIED
  A##-A-##-######Water Heater

Sources

• https://www.building-center.org/a-o-smith/
• https://www.hotwater.com/support/warranty-verification.htmlofficial

A.O. Smith water heater A.O. Smith tankless water heater A.O. Smith heat pump water heater A.O. Smith family Guides