Rinnai Water Heater Age Lookup
Rinnai is one of the most popular tankless brands, spanning the V series, RU, RUR, and Sensei lineups. Enter your serial number to find out when your unit was made and how old it is. Free and quick.
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Finding Your Rinnai Serial Number
Check these four spots on your Rinnai water heater
Common Locations
What to Look For
- White or metallic manufacturer sticker
- Labeled "Serial No." or "S/N"
- Typically 8–12 characters long
- Usually near the model number
Can't find it? Try removing access panels or checking behind the temperature dial.
Rinnai Serial Number Examples
Don't worry if yours looks different - Rinnai has multiple formats and our system can decode most variations.
About Rinnai Water Heaters
Rinnai has been making gas appliances in Nagoya since 1920 and entered North America in 1974. It is the largest tankless supplier on the continent and has built units in Griffin, Georgia since 2018. In North America the line is tankless, though Rinnai does sell storage tanks in other markets, so an Australian Hotflo is a Rinnai too.
The condensing split is where most Rinnai confusion starts, including in a lot of published comparisons. The V and RL families are non condensing. The condensing units are RU, RUR, and the newer RX, and the RX reaches 0.98 UEF, the highest figure in the current catalog. Sensei is the marketing name covering the recent condensing generations. Circ-Logic manages recirculation on models that support it, and outdoor rated versions remove the venting question from the installation entirely.
Residential coverage is 12 years on the heat exchanger and 5 years on parts. The serial opens with a plant letter, then the two digit year, then the two digit production week, so C2312000123 was built in week 12 of 2023. Older units and other market units use a dotted format where a letter pair carries the year and month instead.
Where to find the serial
Rinnai tankless units have the rating plate on the bottom or right side of the cabinet. The serial is a long alphanumeric string and on newer models is also embedded in a QR code that you can scan with the Rinnai app to auto-fill warranty registration.
What the serial actually looks like
Why the age is worth knowing
Rinnai backs residential tankless units with 12-year heat exchanger warranties (15 on Sensei SE+ condensing models), 5 years on parts, and 1 year on labor when professionally installed. Annual flushing is required for warranty validity on water above 7 grains hardness - this is the single most common reason Rinnai denies warranty claims.
Quick answers for this brand
What's the difference between a Rinnai RU and an RUR?
RU is the standard condensing tankless model and RUR adds a built-in recirculation pump for instant hot water. Both share the same heat exchanger platform and the same warranty terms. The RUR draws slightly more power for the pump and costs about $200-300 more new.
How do I read the Rinnai letter-code year?
Rinnai uses a rotating letter code for the production year that cycles every 20-some years (letters A through Z minus a few). The decoder on this site cross-references the letter with the model series to pick the correct decade automatically. If you want to verify, call Rinnai at 800-621-9419 with the serial.
Are Rinnai tankless units made in Japan or the US?
Rinnai operates a manufacturing facility in Griffin, Georgia that builds most North American market units, supplemented by parts and some specialty models from Japan. The serial format is the same regardless of plant of origin.
Need a plumber?
Get free quotes from licensed local pros, no commitment required.
Share this tool with friends!
Know someone with an aging water heater? Send them a free check.