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HVAC age by serial number

How old is that furnace, AC unit, or water heater? Enter the brand and the serial number from the data plate — Choose from 741 HVAC and water-heater brands. The decoder checks supported date formats and tells you when more plate details are needed.

Manufacture date printed on the plate?

Use a date labeled MFG or manufacture date. Enter certification years in ANSI / CSA above.

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The data plate is the metal or foil sticker on the unit — outdoor units have it on the side panel, furnaces inside the front door, water heaters near the bottom. An ANSI/CSA year can help narrow a repeating date code. It is not the manufacture date.

How this works

Nearly every HVAC and water-heater manufacturer encodes the production date inside the serial number — usually the year and month or week, in a format that changed over the decades. This tool knows the serial formats for 741 brands, including sister brands that share a parent company's system (a Tempstar or Heil serial decodes with Carrier's rules; Ruud with Rheem's). Think of it as an HVAC age calculator and serial-number cheat sheet for every brand in one place — instead of hunting through brand-by-brand charts, type the brand and serial and it applies the right era's rules.

Serial number formats by brand

Examples from the same catalog used by the decoder. Formats vary by era and can overlap; enter the complete plate details above to check for ambiguity.

Trane

Furnaces, air conditioners, heat pumps
  • Style 1 (2002-2009, 9 characters)
    2002-2009: 1st digit = last digit of year, digits 2-3 = fiscal week.
    Example91531S41F = April 2009 (week 15; plate MFR DATE 4/2009)
  • Style 1 (2010-present, 10 characters)
    2010+: digits 1-2 = year, digits 3-4 = fiscal week.
    Example10161KEDAA = week 16 of 2010
  • Style 2 (1983-2001)
    1st letter = year (W=1983, X=1984, Y=1985, S=1986, B=1987 ... Z=2001; A, I, O, Q unused), digits 2-3 = production week.
    ExampleR1742DWBF = week 17 of 2000 (plate MFR DATE 04/2000)

6 more Trane formats are in the decoder.

Rheem

Furnaces, air conditioners, heat pumps
  • Style 1
    Older Rheem format: W + 9 digits. Newer format with a letter at position 3 (e.g. W2H0113909) uses a different encoding — see Style 7.
    ExampleW291013412
  • Style 2
    The middle letter is the factory code (typically F, M, G, W, or N). Positions fixed: WWYY follows the factory letter (char 8) — e.g. CB5D302F(09=week)(99=year), EV5D307F(48=week)(97=year).
    ExampleCB5D302F099903346
  • Style 3
    The middle letter is the factory code (typically F, M, G, W, or N). The serial number may or may not contain spaces.
    Example7351 M2806 16735

3 more Rheem formats are in the decoder.

Carrier

Furnaces, air conditioners, heat pumps
  • Style 1 (1980-present)
    WWYY + letter + 5 digits. Can be confused with Lennox. A DATE OF MANUFACTURE is often printed on the tag.
    Example4006A17330 = week 40 of 2006
  • Style 2 (Bryant/BDP 1980s)
    YYMM + 5-digit sequence, all numeric.
    Example850304091 = March 1985
  • Style 3 (U.S., 1980-1984)
    Month letter M-Z (no O/U), then single year digit of the 1980s. Site photo 2 (partly legible V77....) is stated as August 1987.
    ExampleW4D14008 = September 1984

5 more Carrier formats are in the decoder.

Goodman

Furnaces, air conditioners, heat pumps
  • Style 1
    Year is determined by the 1st and 2nd digits, and month by the 3rd and 4th digits.
  • Style 2 (older 8-digit numeric)
    Older 8-digit all-numeric Goodman serial. Year=pos 1-2, month=pos 3-4.
    Example12286306

Lennox

Furnaces, air conditioners, heat pumps
  • Style 1
    The first two digits represent the factory or plant code. Note: the letter I is intentionally skipped to avoid confusion with the digit 1.
    Example1606B13871
  • Style 2
    For months, the serial may use only position 3 or positions 3-4 together.
    Example724

Ducane

Furnaces, air conditioners, heat pumps
  • Style 1
    Enter the full serial and any separate date code shown on the plate.
    Example4140720328
  • Style 2
    Note: the letter I is intentionally skipped to avoid confusion with the digit 1.
    Example4601J19567

Ruud

Water heaters
  • Style 1
    Serial number begins with a prefix such as R, RN, RNG, RHNG, RU, etc.
    ExampleRU 0904B21710
  • Style 2
    Serial number begins with a prefix such as R, RN, RNG, RHNG, RU, etc.
    ExampleRHLN 0106534307
  • Style 3
    Enter the full serial and any separate date code shown on the plate.
    ExampleA141511869

3 more Ruud formats are in the decoder.

Amana

Furnaces, air conditioners, heat pumps
  • Style 1
    Enter the full serial and any separate date code shown on the plate.
    Example0109145052
  • Style 2
    Enter the full serial and any separate date code shown on the plate.
    Example96-90391
  • Style 3
    Enter the full serial and any separate date code shown on the plate.
    Example040590391

American Standard

Furnaces, air conditioners, heat pumps
  • Style 1 (2002-2009, 9 characters) (Trane®)
    2002-2009: 1st digit = last digit of year, digits 2-3 = fiscal week.
    Example91531S41F = April 2009 (week 15; plate MFR DATE 4/2009)
  • Style 1 (2010-present, 10 characters) (Trane®)
    2010+: digits 1-2 = year, digits 3-4 = fiscal week.
    Example10161KEDAA = week 16 of 2010
  • Style 2 (1983-2001) (Trane®)
    1st letter = year (W=1983, X=1984, Y=1985, S=1986, B=1987 ... Z=2001; A, I, O, Q unused), digits 2-3 = production week.
    ExampleR1742DWBF = week 17 of 2000 (plate MFR DATE 04/2000)

9 more American Standard formats are in the decoder.

Payne

Furnaces, air conditioners, heat pumps
  • Style 1
    First four digits = week + year (data tag on the image shows OCT 2006).
    Example4006A17330 = week 40 of 2006
  • Style 2 (early 1980s)
    First four digits = year + month; no letters; used primarily in the early 1980s.
    Example850304091 = March 1985
  • Style 3 (1980-1984)
    Letter M-Z (month, no O/U) + year digit 0-4 (1980-1984) + sequence.
    ExampleW4D14008 = September 1984

2 more Payne formats are in the decoder.

Daikin

Furnaces, air conditioners, heat pumps
  • Style 2
    3-letter plant (FBO Faribault, SCO Scottsboro, STN Staunton) + unit-style letter, then YYMM, then sequence.
    ExampleFBOU0905048200 = May 2009
  • Style 3 (ductless split)
    Daikin-McQuay ductless split: digits 1-4 are a year code (2043=2000, 2044=2001 ... +1 per year), digits 5-6 = week, 7-8 production line, then sequence.
    Example20444501000138 = week 45 of 2001
  • Style 4 (late 1970s-1980s)
    Auburn incremental/heat pump units (EA, EAB, K, EK, EKG, JB, WM, CC, FV): 2-digit unit type, single-digit year (9=1979, 0=1980...), 2-digit week, sequence.
    Example049270032 = week 27 of 1979

6 more Daikin formats are in the decoder.

A.O. Smith

Water heaters
  • Style 1a, 1b, 1c
    Enter the full serial and any separate date code shown on the plate.
    Example1210A002243
  • Style 2
    This style has been discontinued.
    ExampleAF04A093001
  • Style 3
    This style has been discontinued.
    ExampleGG03-1495366-S29

2 more A.O. Smith formats are in the decoder.

Bradford White

Water heaters
  • Style 1
    1st letter = year on a 20-year cycle (A=1984/2004/2024 ... Z=2003/2023; I, O, Q, R, U, V never used), 2nd letter = month (A-M, no I). 7-digit sequence before Dec 2007, 8 digits after. Use the ANSI Z21.10.1 revision year on the tag to pick the cycle (DG... with ANSI 1985 = 1987).
    ExampleDG6322957 = July 1987 or 2007
  • Style 2 (O-prefix computer error, Jan 1997)
    Serials starting 'OA' were issued in January 1997 only, due to a computer error.
    ExampleOA8226825 = January 1997
  • Style 5 (tankless by Rinnai, pre-2009)
    Rinnai-built tankless: YY. MM-sequence (decoded per Rinnai pre-2009 style). Whitespace is ignored, so '04. 03-102521' reads as '04.03-102521'.
    Example04.03-102521 = March 2004

2 more Bradford White formats are in the decoder.

Major brands

Heating and cooling: Carrier, Trane, Lennox, Goodman, Rheem, York, Bryant, American Standard, Ruud, Payne, Amana, Heil, Tempstar, Comfortmaker, Coleman, Armstrong, Daikin, Mitsubishi, Fujitsu, Bosch, Bard. Water heaters: Bradford White, A.O. Smith, American, Rheem, Ruud, Rinnai, Navien, Whirlpool, Kenmore. Type the name as printed on the plate — the rest of the 741 are in the same list.

Older and regional names decode here too — Ducane, Consolidated Industries, Snyder General, Airco, Janitrol, Dayton, Heatcraft, Intertherm, Nordyne, Luxaire, Arcoaire, KeepRite, Day & Night, Frigidaire, Weil-McLain, Burnham, McQuay, AirTemp, Mortex, WaterFurnace, Sanyo, Williams — along with water-heater lines like State and American Water Heater. Many of these share a parent company's serial format, and the decoder knows which.

Why it matters: the age of the mechanicals is one of the biggest hidden costs in a home purchase. A typical AC condenser or water heater near the end of its expected life is a four-figure replacement the listing usually doesn't mention.

Some brands don't encode a date in the serial at all — for those, the tool says so honestly instead of guessing. The manufacture date is sometimes also printed directly on the plate.