How to read a Reliance date code
- Find the serial number on the rating plate (data plate), which also carries the model number. CPSC notices for A.O. Smith gas heaters place the data plate next to the gas control valve/thermostat. Don’t remove covers or panels to reach it.
- Check how the serial starts. Four digits is the year-and-week date code. A letter followed by two digits is the older month-and-year code; where two letters come before the digits, the second letter is the month.
- Read the date. In 0833A032628, 08 is the year (2008) and 33 the week, which falls in mid-August. In an older serial, the month letter comes before the 2-digit year: CPSC’s 2005 recall table (06-002) gives J04 as September 2004. By the same key, L92441351 would be November 1992 (our reading: the official key covers 2004–05 units).
CPSC’s 2018 recall notice, which names Reliance, says “the first four digits represent the year and week of production.” Reliance uses the A.O. Smith and State date code; the full tables are also on our A.O. Smith and State page.
Reliance date code examples
| Serial starts with | Read it as | Example | Built |
|---|---|---|---|
| Four digits (from about 2008) | Year, then week | 0833A032628 | week 33 of 2008 (mid-August) |
| 1211A018632 | week 11 of 2012 (mid-March) | ||
| A month letter (A–M, no I) + 2 digits | Month, then year | L92441351 | November 1992 |
| C91A136750 | March 1991 | ||
| Two letters + 2 digits (A.O. Smith style before about July 2004) | 2nd letter = month, digits = year | AJ03123456 | September 2003 |
Basis: official (CPSC 19-029 for year and week; CPSC’s 2005 A.O. Smith recall table for the month letters, which shows J is September). Examples: 0833A032628 from an InterNACHI forum post (“I’ll go with 33rd week of 08”); the others are serial styles shown by Building Intelligence Center, which gives no dates, so the dates are our reading with the A.O. Smith code. AJ03123456 looks like an illustration rather than a real unit.
Month letters in older date codes
| Letter | Month | Letter | Month |
|---|---|---|---|
| A | January | G | July |
| B | February | H | August |
| C | March | J | September |
| D | April | K | October |
| E | May | L | November |
| F | June | M | December |
There’s no I. Basis: official (CPSC recall 06-002, whose serial table runs from MA04, AA04 or A04 for January 2004 to G05 for July 2005, and J04 for September 2004, for all the models it covers, Reliance’s included).
Week number to month
| Weeks | Month | Weeks | Month |
|---|---|---|---|
| 1–4 | January | 27–30 | July |
| 5–8 | February | 31–35 | August |
| 9–13 | March | 36–39 | September |
| 14–17 | April | 40–43 | October |
| 18–22 | May | 44–48 | November |
| 23–26 | June | 49–53 | December |
Basis: our calculation from the calendar (the month each week number most often falls in); the checker works out the month for the actual year. A week at the start or end of a month can belong to either month, depending on the year.
Who makes Reliance water heaters
RELIANCE is a US trademark for “gas and electric water heaters” owned by State Industries (filed August 5, 1985, per USPTO records). A.O. Smith agreed to buy State Industries of Ashland City, Tennessee in September 2001 and closed the deal that December. Reliance’s support page gives the same Ashland City address and tank support number as the American and A.O. Smith support pages. A New York City equipment approval for American Water Heater’s Johnson City, Tennessee plant also lists “Reliance Water Heater Company” among its trade names.
Basis: official (USPTO data via Justia; A.O. Smith release; reliancewaterheaters.com, americanwaterheater.com and hotwater.com; NYC Department of Buildings) and trade press (Supply House Times).
Recalls to know about
| Recall | What | How to tell |
|---|---|---|
| CPSC 19-029 (Nov 2018) | Ultra-Low NOx 30-, 40- and 50-gallon gas heaters sold as Reliance, A.O. Smith, State and other brands, mainly in California: the burner screen can tear, a fire hazard on combustible floors | First four digits 1115 to 1631; Reliance line 866-880-4661 |
| CPSC 06-002 (Oct 2005) | 75-gallon propane gas water heaters with “A.O. Smith,” “Reliance,” “Apollo,” “State,” or “Maytag” on the side: “The water heaters can accumulate soot on the burners, posing a fire hazard.” About 5,000 units, all brands | Reliance models 675CRRS, 675CRRSD and S7576PE made January 2004 to July 2005: serials beginning MA04, AA04 or A04 (January 2004) through G05 (July 2005) |
| CPSC 04-128 (Apr 2004) | White-Rodgers LP and convertible gas controls on several brands, including Reliance: soot buildup, fire hazard | Date codes 0240 to 0329 stamped on the control (not the heater’s serial number) |
Basis: official (CPSC notices in the sources). Old recalls may have closed; check the notice, and run the model through our recall check.
If you can’t read the date code
Call Reliance tank support at 877-552-0010 (Monday to Friday 8 am to 10 pm, weekends 9 am to 6 pm Eastern). Reliance’s warranty check asks for the serial number; we haven’t used it, so we can’t say whether it shows the manufacture date.
What the age means
A.O. Smith, which owns Reliance’s trademark holder, says tank water heaters last 8 to 12 years. Across published sources a tank typically lasts about 11 years (our summary; most figures fall between 8 and 15). See how long water heaters last.
Buying a house? Put the water heater’s age next to the furnace and AC ages in one home systems age report, and see what a replacement costs installed.
Limitations
- For the older month-letter code, CPSC’s 2005 recall table covers three Reliance models made in 2004 and 2005; for other older Reliance heaters the code rests on A.O. Smith’s and State’s, which CPSC documents.
- The switch from letters to year and week happened around 2008 to 2010; we couldn’t find the exact date.
- Tankless Reliance models are supported by a separate A.O. Smith line, and we found no documented serial format for them.
Checked against the sources below on 6 October 2026.
