Informational Guide

How To Tell How Old A Water Heater Is

by Andrew

A water heater supplies hot water to your home as needed, letting you shower with peace of mind that the hot water won’t suddenly cut out. Unfortunately, water heaters aren't designed to last forever, and they will start to decline over time.  

It's important to know how old a water heater is so you have a good idea of how many years you’ve got left before you need to replace it, and in this guide, we'll explain how to tell how old any water heater is. 

It pays to understand when you’re nearing the time of replacement for your water heater, so you aren’t caught out if it suddenly breaks down. A good quality water heater will last roughly 15 years if it's properly maintained, so by knowing the manufacturing date, you can determine how long is left.  

To find the manufacturing date, you have to locate the serial number. This is the unique number attributed to the water heater, and it will usually tell you the week, month, and year of manufacture. Every brand presents this slightly differently, but the information is the same.  

Your serial number is usually located in the manufacturer’s information on the water heater itself. This is typically a label stuck to the side of the water heater and easy to find, but the serial number may also be in any documentation you received with the water heater.  

The label on the unit will tell you about the energy efficiency and any hazard warnings for the device. Near the bottom of this sticker, you’ll be able to see an 8–10-digit code. This will translate into the manufacturing date. It will also tell you the facility where it was built. 

Locating the serial number and decoding it is the only way to accurately determine the age of your water heater. Remember, buyers and sellers can sometimes lie, but the serial number is a legal requirement and will tell you exactly how old your unit is.  

water heater

How Old Is My Water Heater? (Finding Age Of Popular Water Heaters) 

The serial number is the key to determining the age of your water heater, but unfortunately, every brand sets their code out slightly differently. We've given a guide for the most popular brands so you can quickly determine when it was made and how old it is.  

Whirlpool Water Heater 

Whirlpool serial numbers can be found on a sticker near the bottom of the device, and you can use their serial number lookup tool to get more information about your model. The serial number is typically 10 digits, but you only need the first 4. The 1st and 2nd numbers will tell you the year, and the 3rd and 4th will tell you the month. For example, if it showed 1905XXXXXX, the water heater was made in May 2019.  

Bradford White Water Heater 

The Bradford White water heater serial number is probably the most difficult to decipher, but they have published guidance to help you out. The serial number can be found on a sticker on the very front of the water heater, but there is quite a lot of information on the gas water heaters, so it may take a minute to see it.  

There are 10 letters and numbers in the Bradford White serial number, but you only need the first 2 letters. The 1st letter tells you the year it was made, and the 2nd tells you the month. To work this out, you'll need to follow the key below:  

Letter 

Year 

Month 

A

1984 or 2004 

January 

B

1985 or 2005 

February 

C

1986 or 2006 

March 

D

1987 or 2007 

April 

E

1988 or 2008 

May 

F

1989 or 2009 

June 

G

1990 or 2010 

July 

H

1991 or 2011 

August 

J

1992 or 2012 

September 

K

1993 or 2013 

October 

L

1994 or 2014 

November 

M

1995 or 2015 

December 

N

1996 or 2016 

N/A 

P

1997 or 2017 

N/A 

S

1998 or 2018 

N/A 

T

1999 or 2019 

N/A 

W

2000 or 2020 

N/A 

X

2001 or 2021 

N/A 

The most confusing aspect is the 20-year cycle that Bradford White has used on their serial numbers because it means the 1st letter could be one of two options 20 years apart. For example, if the serial number says WKXXXXXXXX, it means that the water heater was made in October 2000 or October 2020. However, you should be able to work out which year it is fairly quickly by looking at the condition of the unit.  

Rheem Or Ruud Water Heaters 

The serial number on Rheem and Ruud water heaters is on a label on the right-hand side of the heater body.

The label itself is very large, but the serial number is fairly small and near the bottom, so it can be tricky to spot. Rheem publishes guidance on reading the serial number here, but it’s fairly straightforward.  

The first 2 numbers tell you the month it was made (e.g., 01 is January).

The next 2 numbers tell you the year it was manufactured, and the letter afterward is the plant code for where it was made. The last 4 numbers are a unique identifier code for your unit, which is useful for warranties.  

Rheem residential hot water heater

Once you have those first 4 digits of the serial number, you’ll be able to work out the month and year your water heater was made and establish how old it is. 

Lochinvar Hot Water Heater 

Lochinvar has a confusing serial number coding system, and their water heaters will have either an 8 or 10 digital serial number depending on how old it is. If it was made before 2012, it will have an 8-digit number, and it's the first 2 letters that will tell you the month and year. Confusingly, they don’t go in order, so we’ve given you a key in the table below: 

Letter 

Year 

Month 

A

2004 

January 

B

2005 

February 

C

2006 

March 

D

2007 

April 

E

2008 

May 

F

2009 

June 

G

2010 

July 

H

2011 

August 

J

2012 

September 

K

1993 

October 

L

1994 

November 

M

1995 

December 

N

1996 

N/A 

P

1997 

N/A 

S

1998 

N/A 

T

1999 

N/A 

W

2000 

N/A 

X

2001 

N/A 

Y 

2002 

N/A 

Z 

2003 

N/A 

Therefore, if your serial number was BCXXXXXX, your water heater was made in March 2005.  

If your Lochinvar water heater was made after 2012, it will have a 10-digit serial number which is a lot more straightforward. The 1st and 2nd numbers will tell you the year, and the 3rd and 4th numbers will tell you the month. If your serial number was 1801XXXXXX, it means your water heater was made in January 2018.  

The serial number itself is fairly easy to find and should be with the information stuck on the outside of the heater. More information about their serial numbers can be found here. 

American Standard Water Heater 

American Standard water heaters have a label on the top 1/3 of the unit's right-hand side. If it's a gas-powered model, it will be right by the gas valve, and it's usually easy to find. This label will contain safety information and the serial number. 

The American Standard serial number consists of 10 digits, but you only need to know the first 4. The 1st and 2nd numbers are the year of manufacture, and the 3rd and 4th are the week of the year. So, if it was 0216XXXXXX, it would be the 16th week of 2002, which is about mid-April of that year.  

Navien Water Heater 

Navien has a straightforward and accurate system with their serial numbers so you can determine exactly how old it is. The serial number can be found on a label on the water heater itself and on the packaging. It consists of 10 numbers, but you only need to worry about the first 5 or 6. The 1st and 2nd numbers will tell you the year, the 3rd and 4th the month, and the 5th and 6th the day. So, if your serial number is 170812XXXX, your water heater was made on 12th August, 2017.  

State Water Heater 

State Water heaters have a clear label on the unit, which shows the serial number at the top. There are two different formats, one has a mix of 10 numbers and characters and starts with 4 digits, and the other has a mix of 11 numbers and characters, which start with a letter and then 4 numbers.  

If your serial number is 10 numbers and characters long, then the 1st and 2nd digits show the year, and the 3rd and 4th digits indicate the month. If your serial number is 11 numbers and characters long, then the 1st and 2nd numbers after the letter show the year, and the 3rd and 4th numbers after the letter show the month.  

AO Smith Water Heater 

The AO Smith water heater label and serial number are located near the bottom of the appliance, and they've published guidance to help you out. The code itself is exactly the same format as used by American Standard, so you only need to know the first 4 digits to establish how old the water heater is.  

ao smith water heaters

GE Water Heater 

GE water heaters have some guidance on how to find your serial number, and you can find it on a label on the side of your unit. Their serial numbers use the same coding system as Rheem, so you can follow those instructions to determine when it was made.  

U.S Craftmaster Water Heater 

U.S Craftmaster water heaters have a clear serial number printed on a label on the side of the unit, and it can be found on the packaging and user documentation too. The serial number doesn't contain as much information as some other brands and will only show you the year of manufacture. This can be found in the first 2 digits of the serial number, so if it is 14XXXXXXX, then it was made in 2014.  

John Wood Water Heater 

John Wood has published an FAQ online about their serial numbers because it's a little bit complicated. Once you locate the serial number on the side of the unit, you only need to concern yourself with the first 4 numbers, ignoring any letters which might be at the start. If your device was manufactured before 2008, then the 1st and 2nd numbers will show you the year, and the 3rd and 4th numbers will show you the month. If it was manufactured after 2008, the 1st and 2nd numbers will show you the year, but the 3rd and 4th numbers will show you the month.  

For example, if your serial number starts 0706XXXX, it means it was made in June 2007. If your serial number starts 1236XXXX, it means it was manufactured in the 36th week of 2012, which is mid-September.  

Rinnai Tankless Water Heater 

The make, model, and serial number can be found on the left side panel of your Rinnai tankless water heater. Rinnai also has two different coding systems in operation depending on when your water heater was manufactured. If your water heater was manufactured before 2009, then the 1st and 2nd numbers in the serial number are the year, and the 3rd and 4th numbers are the month. So, if your serial number starts 0603XXXX, it means it was manufactured in March 2006.  

However, after 2009 Rinnai switched to a letter-based system, so you need to look at the first two letters in the serial number. The 1st letter relates to the year, and the 2nd letter relates to the month, as shown below.  

Letter 

Year 

Month 

A

2009 

January 

B

2010 

February 

C

2011 

March 

D

2012 

April 

E

2013 

May 

F

2014 

June 

G

2015 

July 

H

2016 

August 

J

2017 

September 

K

2018 

October 

L

2019 

November 

M

2020 

December 

N

2021 

N/A 

Takagi Tankless Water Heater 

Takagi tankless water heaters have an easy-to-find serial number in all the documentation, but if it was produced before 2010, then the serial number doesn't include the date of manufacture. If your water heater was made after 2010, the 1st and 2nd digits would show the year, and the 3rd and 4th digits will show the week. So, if your serial number started 1812XXXX, your water heater was made in the 12th week of 2018.  

If the date of manufacture isn't included in the serial number, you'll need to contact their customer service line to find out the age of your unit.  

Bosch Tankless Water Heater 

Bosch has a serial number locator guide to help you find it on the unit and understand the code, but it's fairly easy to find on the water heater panel. Bosch has a slightly confusing system, and your serial number may start with letters or numbers. All you need is the first 3 or 4 numbers to understand the month and year of manufacture.  

The 1st number is the year itself, and the 2nd is the decade it relates to, with 6 being the 1990s and 8 being the 2000s. The 3rd number relates to the month of manufacture. So, if your serial number starts 583XXXXX then the Bosch tankless water heater was made in March 2005.  

Most Bosch water heaters made after 2010 have abandoned this system and just labeled the manufacture date on each unit.  

Noritz Tankless Water Heater 

Noritz tankless water heaters have the serial number printed on the bottom of the data plate on the side of the unit. There's no real code with Noritz, and the start of the serial number will clearly show the year and then the month, so it's easy to see how old it is.  


People Also Ask (FAQs)  

How long do water heaters generally last? 

A well-maintained water heater will last around 15 years, but some cheaper models may only last 10. 

What is considered old for a water heater? 

Anything over 10 years is considered old for a water heater, and it's typically after this point you'll start to encounter performance issues and leaking.  

Where is the manufacture date on a serial number? 

Every serial number is slightly different, but the manufacture date is usually the first few numbers or letters. Most modern serial numbers used 4 numbers to indicate the month and year of manufacture.  

How do I look up a serial number? 

If you look on the manufacturer’s website, they usually have a serial number lookup page you can put the number into.   


Conclusion

A properly maintained water heater will last 10-15 years, but the performance will start to decline after that point. Knowing the heater's age can help you understand how long it will be in working order so you can decide when to replace it. Hopefully, you now know how to determine how old your water heater is.    

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