How old is my water heater?

Water Heater Installation Experts
Manufacturer
Other common brands
by same Manufacturer
Date within
Serial Number  
Serial Number
Date format 
 American Water Heater Co
(A.O. Smith aquired in 2006)  
Many brands - some include  
US Craftmaster
Whirlpool   
Position 1-4 YYWW******
 A.O. Smith
Glascote
Perma-glas
Position 2-4
Position 1-3
*UYY*****
UYY*******
 Bradford-White Corp
Jetglas
Position 1-2 VU*******
 Lochinvar Corp
Energy Saver
Golden Knight
Knight
Position 1-2 VU*******
 Rheem Corp
Many brands - some include
GE
Hot Point
Ruud
Richland
Position 1-4
MMYY******
(Ignore leading
alpha characters
i.e. RN, GE, HTPLG) 
 State Industries
(A.O. Smith aquired in 2001)
Many brands - some include
ACE
Kenmore
Reliance
Position 1-3
Position 1-4
UYY******
(YYWW*******
used after 2007)
YY=Year MM=Month WW=Week U=Letter Month** V=Letter Year***

** A=Jan B=Feb C=Mar D=Apr E=May F=Jun G=Jul H=Aug J=Sep K=Oct L=Nov M=Dec

*** A=2004 B=2005 C=2006 D=2007 E=2008 F=2009 G=1990 H=1991 J=1992 K=1993 L=1994 M=1995 N=1996 P=1997 S=1998 T=1999 W=2000 X=2001 Y=2002 Z=2003
The age of your water heater is not always easy to determine. Often, the age can only be determined by the serial number. Over 100 separate water heater brands are manufactured by six companies. Even some of these companies have merged recently. Use the following table to determine the age of your water heater based on its serial number.
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