Rinnai tankless water heater Age: Know how old it is

As we discussed earlier in our previous article that tankless heaters life span ranges from 13-20 years with good maintenance. In this long period we may forget its age or date of manufacture, we look for paperwork to find its age but sometimes they may be lost. Even if you are thinking to buy a used water heater one thing which saves us is the serial number printed on the water heater.

Rinnai Serial number location

First thing we need to look for is the serial number of the Rinnai Water Heater. It is printed on the silver or white sticker label pasted on one side the water heater. The label has the details of the company, model number, serial number, Country in which it is produced and few certifications which the heater has passed.

rinnai serial number location

Rinnai water heater age can be determined from serial number, Rinnai serial number pattern has only 2 types. Since 2009 the serial number pattern is unchanged and you can see the same pattern in the latest model units.

Let’s see few example labels of both serial number patterns and learn how to decode them and find our Rinnai heater age.

Pattern 1 (AB. CA -123456) (created in 2009)

As soon as you see the alpha-numeric serial number (AB. CA-123456) the date and month of manufacture will be the first 2 alphabets before the dot. Here in our example we have AB, first letter represents YEAR and second one represents MONTH. From the below serial number format chart match the alphabets with year and month to find the age.

Rinnai water heater serial number format chart

Now lets see some real serial numbers printed on heaters and find their age from the above format chart.


rinnai water heater serial number label

From the above label you can see the serial number printed as NK. CA-129326 . Here we need to look the first 2 alphabets before dot which are NK in this example. We should look into the above table to match the alphabets with YEAR and MONTH respectively. First letter N represents YEAR which is 2021 and K represents MONTH which is OCTOBER. So it is October 2021 manufactured water heater.

Note: In Year chart don’t blindly compare year with alphabets as some alphabets like I,O,Q,U are not listed to avoid confusion with numbers.

Pattern 2 (01. 02-123456)( used Before 2009)

Before 2009 Rinnai used only numerical serial number. This pattern is nearly same and does not require any chart to match with, we can easily find the year and Month of manufacture of the heater directly. The first 2 numbers before the dot represent the year and another 2 digits between the dot and hyphen represents the Month.

rinnai heater age using serial number before 2009

From the above image of an old rinnai water heater label before 2009 we can see the serial number 07.12-123810. Here 07 indicates the year 2007 and 12 indicates the month of December. It also has the month and year printed beside the serial number which makes it very easy to read.

Find Rinnai water heater age without serial number

In case if your water heater became old and the serial number label is worn out or someone removed it, you may not find the serial number easily. In that case there are few other ways to find the age of the heater without serial number.

  • Look for any paperwork done at the time of purchase, warranty papers if available, the date is printed on them which helps to identify the age.
  • If you paid online for unit or for installation, you can find the transaction date.
  • If you don’t have any of these you can find the approximate age by checking the technology used in it and comparing with the models launched in previous years.
  • We can also estimate the age roughly through the physical appearance, if it is rusted and has scratches over the body and parts, look the heat exchanger color, is it looking new or old.
  • Finally if you don’t know anything about it, ask Rinnai support team about it online or when you plan official maintenance of the unit.

We hope this article helped you in finding the age of your Rinnai water heater. If you still have any doubts please comment below or contact us with your serial number, we will definitely help you.

Joseph Miller

Joseph Miller is a highly experienced water heater repair expert with a passion for keeping homes warm and comfortable. With over 50 years of industry expertise, Joseph has developed a deep understanding of water heater systems and the intricacies of their repair and maintenance.

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