Trane and American Standard are the same equipment. Serials from 2010 onward start with the year and week. From 2002 to 2009 the first digit is the year's last digit. From 1983 to 2001 the first letter is the year. Most plates since the late 1980s also print the date, so check for that first.
Since the late 1980s most Trane and American Standard plates print the manufacture date (MFG DATE), usually top right. Use that if you see it.
The first two digits are the year and the next two are the week.
11241KADBB reads as week 24 of 2011.
Two sources agree Building Intelligence Center, PickHVAC, Parts Town, McGarry and Madsen Home Inspection
On nine-character serials from 2002 to 2009 the first digit is the last digit of the year and the next two are the week.
7165RHAIG reads as week 16 of 2007.
Two sources agree Building Intelligence Center, PickHVAC, Energy Trust of Oregon furnace chart, Inspector's Journal decoder, Parts Town
The first letter is the year (W is 1983, X 1984, Y 1985, S 1986, then B is 1987 through R for 2000, and Z is 2001). The next two digits are the week.
B50632891 reads as week 50 of 1987.
Two sources agree Building Intelligence Center, PickHVAC, Parts Town, Energy Trust of Oregon furnace chart, InterNACHI inspector forum, McGarry and Madsen Home Inspection
The first letter is the factory. The next two digits are the year and the letter after them is the month.
C94L14723 reads as November 1994.
Two sources agree PickHVAC, Building Intelligence Center
A gas furnace usually lasts 15 to 20 years. Well-maintained units in mild climates reach 25; units that run hard with dirty filters fail sooner.
How long does a furnace last? · Should I replace my furnace? · HVAC.com, Lennox, InterNACHI (15-25)
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