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How to Determine the Age of a Water Heater (Complete Guide)

water heating system

Water heaters last an average of about 10 years, though some models can last twice that under the right conditions. When your water heater starts to go bad, you might end up with muddy or rusty water, you could hear loud clanging noises from the heater, and you might not get any hot water, or the water could be very slow to heat.

It’s in your best interest to replace your water heater before it goes out. Once it dies, you’ll be left without hot water while you’re waiting for repairs. But if you want to stay on top of replacement, you’ll need to know how old your water heater is so you can determine when it needs to be replaced. This isn’t a terribly difficult process, but you do have to know what to look for, which is what we’re going to discuss in this article. By the end, you’ll be able to tell how old your water heater is, giving you a good idea of how much more life it’s got left in the tank.

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Read the Label

Reading the label is the easiest way to tell how old your water heater is. Granted, not every water heater has a label, but if yours does, it should make it easy to figure out when it was made. Most manufacturer’s labels list an installation date, which is close enough to the manufacture date for you to use. Just count back the number of years since the install date and you’ll know how old the heater is.

Decode the Serial Number

If your water heater doesn’t have a label or the label doesn’t display an installation date, then you’ll need to decode the serial number instead. Each serial number contains the information needed to determine the heater’s manufacture date. The only issue is that decoding the serial number can be a pain. It wouldn’t be too bad if every water heater serial number utilized the same dating system, but that’s not the case. Each manufacturer has its own method of formulating serial numbers, and these can even change from year to year.

You also need to understand the difference between a manufacturer and a brand. Manufacturers build products. Brands are just labels that the products sell under. One manufacturer can build water heaters for many brands. Heaters from different brands but the same manufacturer will have serial numbers that are decoded the same way, provided they are from the same time period.

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A.O. Smith and American Water Heaters

AO Smith EJC-6 Residential Electric Water Heater

Included Brands:

  • O. Smith
  • Ace
  • Agua Therm
  • American hardware
  • Apex
  • Aqua Temp
  • Aquamatic
  • Best
  • Champion
  • Craftmaster
  • De-Limier
  • De-limier
  • Deluxe
  • Eagle
  • Earl’s Energy Saver
  • Environtemp
  • Four Most
  • Glascote
  • GSW
  • Hotmaster
  • Hotstream
  • King-Cleen
  • King-line
  • Master Plumber
  • Mor-Flo
  • National
  • Neptune
  • Penquin
  • PermaGlas
  • Premier
  • Prestigfe
  • Proline
  • Quaker
  • Quick-Flo
  • Raywall
  • Revere
  • Riveria
  • SABH
  • Sands
  • Sentinel
  • Service-Star
  • Shamrock
  • Special Delux
  • Standard
  • Super Eagle
  • Sure-Fire
  • Thoro-Clean
  • Tru Value
  • Tru-Test
  • S. Supply
  • Whirlpool
  • XCL Energy Saver

How to Decode

Serial Number Style 1: 1714******* (Week 14 of 2017)

The first serial number style applies to models built since 2008 and is still being used at present. The first two digits represent the year. In this case, 17, which means 2017. The next two digits represent the week. Here, 14 signifies that the heater was built during the 14th week of the year.

Serial Number Style 2: *C05******* (March, 2005)

In this style of serial number, which was used prior to 2008, the second digit is a letter that represents the month of the year the heater was built. The letters go in order with the months chronologically from A to N skipping I. So, January is A, February is B, March is C, all the way to December at letter N. Digits three and four indicate the year of manufacture. In this example, we can see the letter C signifies the heater was built in March, and the 05 shows it happened in 2005.

Rheem and Ruud

Rheem RTEX-18 18kW 240V Electric Tankless Water Heater

Included Brands:

  • ABS
  • Aqua Therm
  • Cimarrom
  • Citation
  • Coast to Coast
  • Energy Master
  • General Electric
  • Intertherm & Miller
  • Lowe’s
  • Mainstream
  • Montgomery Ward
  • Professional
  • Rheem
  • Richmond
  • Ruud
  • Servi-Star
  • True Value
  • Vanguard
  • Vista Therm

How to Decode

Serial Number Style 1: 1012****** (October, 2012)

Here, the first two digits stand in for the month, while the following two digits represent the year. In this example, 10 shows that the heater was built in October while the 12 represents the manufacturing year of 2012.

Serial Number Style 2: *1608***** (16th week of 2008)

In this style, the first digit isn’t used in the date. Digits two and three will indicate the week of the year that the heater was born with the following two digits expressing the year. We can see in this example that digits two and three make 16 while digits four and five are 08, meaning the heater was manufactured in the 16th week of 2008.

Serial Number Style 3: **2898****** (28th week of 1998)

With serial number style three, the first two digits have nothing to do with the manufacture date. Digits three and four, however, represent the week that the heater was built, while the following two digits indicate the year. As you can see in our example, the numbers 2898 as digits 4-8 show that the heater was built in week 28 of 1998.

Serial Number Style 4: ****0705****** (July, 2005)

Unlike the other styles of serial numbers, here, none of the first four digits are used for the date. Rather, digits 5-8 will be used instead. Digits five and six will show the month while seven and eight will be the year. With digits five through eight being 0705 in this example, we know the heater was built in July of 2005.

Serial Number Style 5: 06.08****** (June, 2008)

This is probably the easiest serial number style to decode. The first four digits represent the date of manufacture, with two digits for the year followed by two digits for the month, separated by a period. Our example shows 06.08, which can be decoded as June of 2008, with 06 representing the month of June and 08 after the decimal indicating that 2008 was the year of manufacture.

Bradford White Water Heaters

Bradford White D-100T-199-3N Electronic Ignition Gas Water Heater

Included Brands:

  • Bradford White
  • Jetglas

How to Decode

Bradford White has a confusing serial number system to decode. It involves just two letters, with the first letter representing the year and the second letter showing the month that the heater was manufactured. The letters A through M represent the months chronologically, starting with A for January, B for February, and so on, down to M for December. Deciphering the years is more confusing still. Each letter from A to Z represents two years that are 20 years apart.

  • A – 1984 or 2004
  • B – 1985 or 2005
  • C – 1986 or 2006
  • D – 1987 or 2007
  • E – 1988 or 2008
  • And so on…

You can continue this pattern to our current year, which is represented by the letter X.

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If you’re lucky enough to find a label on your water heater with an installation date printed on it, then determining the age of your water heater will be easy and simple. On the other hand, if you have to decode its serial number to figure out when it was made, you’ll need to know how to decode the specific serial number your heater has. Unfortunately, there are many different systems used to encode the date of manufacture into the serial number of a water heater, but using this guide, you should be able to figure out when yours was made.

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Featured Image Credit: nikkytok, Shutterstock


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