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This is the crucial step. The decoding method depends entirely on the manufacturer. Here are the most common formats: * **A.O. Smith, State, Kenmore, Reliance (and others made by A.O. Smith):** The first two numbers are the year of manufacture, and the next two numbers are the week. For example, a serial number starting with `1805...` was made in the 5th week of 2018. * **Rheem, Ruud, Richmond:** The serial number format is often `MMYYP...`. The first two digits are the month, and the next two are the year. For example, `0419...` means it was made in April 2019. * **Bradford White:** This brand uses a letter code for the year and a letter code for the month. The first letter represents the year (A=2004, B=2005, etc., skipping some letters). The second letter represents the month (A=Jan, B=Feb, etc.). You will need to look up the manufacturer's specific year code chart online. Since we assumed the brand is **A.O. Smith**, we will use that format. Look at the first four digits of the serial number you recorded. The first two digits represent the year, and the second two digits represent the week of that year. For example, a serial number `1732J123456` means the heater was manufactured in the 32nd week of 2017.

You're viewing a step from: How to Decode Your Water Heater's Serial Number to Find Its Age

Beginner

30 minutes

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This guide provides instructions on how to locate the manufacturer's data plate on a water heater, identify the serial number, and interpret its code to accurately determine the unit's manufacturing date and age. This is a crucial step in assessing the health of your water heater and planning for maintenance or replacement.

Based on content fromThis Old House· 2.2M subscribers

Frequently Asked Questions

Is it safe to touch my water heater, and should I take any precautions before locating its data plate?

Yes, it's generally safe to examine your water heater. Always ensure your hands are dry and avoid touching any exposed electrical wiring or gas lines. For gas units, quickly check for any signs of gas leaks or unusual odors before proceeding.

I can't find the data plate on my water heater. Where is it usually located?

The manufacturer's data plate, or label, is typically a sticker or metal plate found on the side of the tank, near the top, or sometimes on the front access panel. Use a flashlight and gently clean any dust or debris if it's hard to read.

Once I find the serial number, how do I actually decode it to find the manufacturing date?

Most manufacturers embed the date within the first few characters of the serial number, often in YYMM or MMYY format. For example, '0810xxxxxx' could mean October 2008. If this pattern doesn't fit, check the specific manufacturer's website or an online decoding chart for your brand.

Why is it important to know the exact age of my water heater?

Knowing your water heater's age is crucial for proactive home maintenance and budget planning. Most units have a lifespan of 8-12 years, and older ones become less energy-efficient and are more prone to unexpected failures, which could lead to costly water damage.