How to read Navien water heaters and boilers serial numbers

Reading it yourself

• 15 or 16 characters: four digits, a letter, then digits. The two digits after the letter are the year. The next character is the month: 1 to 9, then X for October, Y for November and Z for December. The two digits after that are the day.

  Example: 7414C14X1771143 was made in October 2014.

This is the date the unit was made. It was usually installed soon after, but it can be later. If a serial doesn’t fit any of these patterns, look on the label for a printed manufacture date.

Sources

Checked in October 2026.

• Navien condensing tankless water heaters and combi boilers recall, CPSC (via Justia)
• Navien water heater and boiler age, Building Intelligence Center