ToftThis covers Rinnai. The serial number is on the rating plate. On a wall furnace it's on the right side, with the date code at the bottom. On a tankless heater it's on the side or the front.
Before about 2009: nine to twelve digits, no letters. The first two digits are the year and the next two are the month. Newer Rinnai serials start with letters, and we can't read those yet.
Example: 9704811080 was made in April 1997.
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.
Checked in October 2026.
Free for 30 days. No card to start.
Start free