Read the date before the production number
The current layout has four letters and six numbers. The first letter names a year; the second names a month. The other two letters identify the location and product type. For example, BH.AB-000123 means August 2010. Periods and dashes do not change the reading.
Rinnai’s service manual and Building Intelligence Center agree on the letter table. The manual’s June 2010 changeover date refers specifically to direct-vent furnaces; BIC dates the water-heater letter format from 2009.
Year letters are not a simple alphabet count
A–H mean 2009–2016; J, K, L, M and N mean 2017–2021; P, R, S and T mean 2022–2025; W, X, Y and Z mean 2026–2029. Do not assign a year to I, O, Q, U or V. One inspector reference mentions O on a special model, but the maker’s table does not confirm it.
Month letters run A–H for January–August, then J–M for September–December. The year and month alphabets differ: W is a year code, never a month.
Older numeric serials
A ten-digit serial such as 04.03-102521 begins with year 04 and month 03: March 2004. This page supports that water-heater layout from 1999 through 2008. Shorter early serials are left undecoded because a second independent confirmation was not found.
Common questions
Does the serial show the installation date?
No. It records manufacture. Use the installer’s invoice for installation or warranty registration.
Where is the Rinnai serial label?
Look on the exterior side panel. Copy the complete serial, such as four letters followed by six digits, rather than a model name such as RU or RUR. A longer inventory or app identifier may include extra text that is not the serial.
Worked examples
| Serial | Style | How it reads | Made | Example from |
|---|---|---|---|---|
BHAB000123 | Year letter + month letter | B = year letter (2010); H = month letter (August) | August 2010 | Rinnai |
BLCA051306 | Year letter + month letter | B = year letter (2010); L = month letter (November) | November 2010 | Building Intelligence Center |
0403102521 | Older year + month, six-digit sequence | 04 = year ’04; 03 = month (March) | March 2004 | Building Intelligence Center |
Not affiliated with Rinnai. Brand names describe decoder compatibility. Manufacture date is not installation date.
Sources
- Rinnai: Serial Number Format, service manual p. 127Used for: Year letter + month letter; Older year + month, six-digit sequence.
- Building Intelligence Center: rinnai water heater ageUsed for: Year letter + month letter; Older year + month, six-digit sequence.