Step 3 · Decode the Serial Number
Now, interpret the serial number using the manufacturer's specific format. Most brands embed the manufacturing date within the first few characters. Here are some of the most common formats: * **Rheem / Ruud:** The first four digits represent the month and year of manufacture (MMYY). Example: A serial number starting with `1221` was made in December (12) of 2021 (21). * **A.O. Smith:** The first two digits represent the year of manufacture (YY). The next two digits represent the week of that year. Example: A serial number starting with `2034` was made in the 34th week of 2020. * **Bradford White:** Uses a letter-based code. The first letter represents the year, and the second letter represents the month. Year Code: A=2004, B=2005, ..., G=2010, ... S=2020, T=2021, etc. (skips 'I', 'O'). Month Code: A=Jan, B=Feb, ..., L=Dec. Example: `TG...` means the unit was made in July (G) of 2021 (T). If you have a different brand or are unsure, use your smartphone or computer with internet access to search for "[Your Brand Name] water heater serial number lookup".