How old is my Takagi tankless water heater?
Serial number age decoder for Takagi tankless water heaters: 3 format eras, the decode rule in plain English, transcribed tables, and the official lookup.
Type the serial from the data plate, not the model number. Nothing is sent anywhere; the tables are in this page.
Format example: 1544E000453
- Takagi tankless water heater serial numbers in the 2010 to present format encode the year as digits 1-2 (20YY) and the week as digits 3-4 (source: building-center.org).
- Example: serial 1544E000453 decodes to week 44 of 2015.
- Takagi tankless 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.
- Takagi's official lookup at takagi.com returns warranty / registration lookup.
Format eras
- 2010 to present VERIFIED
####A######digits 1-2 (20YY) - before 2009 VERIFIED
######## - 2008 to present VERIFIED
####A######digits 1-2 (YY) after optional leading S
How to read the serial
2010 to present formatVERIFIED
Shape ####A###### · example 1544E000453 / 1816104327281 · confidence high
- Year
- digits 1-2 (20YY)
- Week or month
- week = digits 3-4
- Plant
- letter 5 when present
Example: serial 1544E000453 decodes to week 44 of 2015.
before 2009 formatVERIFIED
Shape ######## · example 33001941 · confidence high
2008 to present formatVERIFIED
Shape ####A###### · example 1210A002243 / S1318 F000046 / 1836111786352 · confidence high
- Year
- digits 1-2 (YY) after optional leading S
- Week or month
- week = digits 3-4
- Plant
- letter after the 4 date digits (unpublished)
Example: serial 1210A002243 decodes to week 10 of 2012.
Listed under A.O. Smith in the source; Takagi is named in that format's family and the corporate link is an estimate, not a checked fact.
Where the data plate is on a tankless water heater
On the side or bottom of the wall-hung cabinet, or inside the front cover on the frame.
General guidance, not brand-specific: the owner's manual or the installer can point to the exact spot. See the data plate guide.
For scale only: the InterNACHI Standard Estimated Life Expectancy Chart for Homes lists Instant (on-demand) Water Heater at 10 years of expected service (nachi.org). That chart is a guideline, not a prediction for your unit.
Open the official Takagi lookup takes serial number; returns warranty / registration lookup; URL verified live
This site is a reference built from published tables. The manufacturer's own lookup wins whenever the two disagree.
What we could not confirm
- The before 2009 format is documented but not decodable here: no year decode text.
- Takagi is treated as sharing A.O. Smith's format because the source lists it in that family; the corporate relationship itself is an estimate.
- Post-2009 serials are AO Smith YYWW; pre-2009 8-digit serials are sequential with no date.