How to Find Out the Age of a Hot Water Heater, Heating Furnace, or Boiler
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Here is a Water Heater Data Decoding Document that Aids in Determining Water Heater Age
Here is a Heating Furnace or Boiler Data Decoding Document that Aids in Determining Water Heater Age
How long should a hot water maker or hot water heater last
What factors determine the life of a water heater - independent of the water heater's age?
Questions & answers about how to find out the age of a heating appliance: water heater, heating boiler, heating furnace

Here we explain how to determine the age of a water heater, we provide a chart that decodes the year of manufacture of water heaters, and we discuss the conditions, maintenance, and factors that affect how long a water heater can be expected to last.

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How to Determine the Age of a Water Heater

A chart that decodes water heater age from water heater label data has been provided by NACHI member Scott LeMarr. Also see AGE of PLUMBING MATERIALS & FIXTURES. Our photo at page top shows an oil fired water heater with a backpressure problem and other safety concerns like a missing extension tube on that relief valve, and maybe a missing draft regulator and perhaps an oil line that is not protected from damage. The data tags (containing the water heater's age) for this heater are hidden by its insulating blanket. Readers who need to determine the age of air conditioning and heat pump equipment should see A/C DATA TAGS.

How can we determine the age of a residential water heater? By looking at and decoding data on the water heater's label.

Nearly all modern water heaters, electric, oil fired, or gas fired, include data tags and stickers that indicate the year and month of manufacture of the water heater.

That doesn't tell you exactly when a water heater was installed in a particular building but it does indicate the age of the water heater itself.

However some manufacturers encode the year and month of manufacture of their water heater in the product's serial number so that the water heater age is not immediately obvious.

Our photo (left) shows a gas-fired Rheem™ water heater. The label containing the unit's serial number is probably at the water heater top left. The label above the gas control at the water heater bottom typically contains water heater lighting instructions.

Carson Dunlop provide a most-comprehensive Technical Reference Guide to heating and cooling equipment manufacturers that includes water heater manufacturers. For an encyclopedic reference including manufacturers, history, contact information, and serial number decoding we recommend this book.

Scott LeMarr has generously shared his free Water Heater Age Determination Chart that decodes both furnace age and water heater age. He includes data for many brands of water heater, including hot water systems produced by the manufacturers listed just below.

Water heater age is encoded in data on the information label on these water heaters: Ambassador water heaters, American water heaters, ACE water heaters, A.O. Smith water heaters, Apollo, Aqua Temp, Aqua Therm, Best water heaters, Bosch water heaters, Bradford White, Cafos, Champion, Crosley, Energy Saver, Envirotemp water heaters, GE water heaters, Glascote water heaters, Golden Knight water heaters, GSW, Hotpoint water heaters, JC Penny, Jetglas, JW or John Wood, Kenmore water heaters (Sears Brand), Lochinvar, Lowes, Mainstream, Maytag water heaters, Montgomery Wards, Knight, PermGlas, Reliance water heaters, Revere, Rheem water heaters, Rheem/Rudd/Richmond water heaters, Rinnai, Security, Shamrock water heaters, Standard water heaters, State/Reliance/Sears brand water heaters, Thermo-King, Vanguard water heaters, US Craftsmaster, US Water Heaters, and Whirlpool water heaters.

Here is A Chart that Decodes the Date of Manufacture of a Hot Water Heater

Use the following link to see Mr. LeMarr's Furnace and Water Heater Age Chart in .pdf form. (Use the "BACK" button on your browser to return to InspectAPedia.com.

Our photo (above-left) is from the A.O. Smith EnergySaver water heater in our laboratory. The unit's serial number, MM02-2147713-260 identifies the model and its date of manufacture. The "02" following MM indicates that this unit (in our laboratory) was manufactured in 2002 and the -2 following the MM02- decodes to February.

Rheem water heater label (C) Daniel Friedman In a second example, Rheem water heaters provide first the month MM and then the year in the first four digits of the water heater's serial number.

The label shown here includes 0884 at the beginning of the serial number - August 1984.

Mr. LeMarr points out that in the U.S. the remaining actual manufacturers of domestic hot water heater heaters are American, A.O. Smith, Bradford White, and Rheem companies, though their products may be branded among the many names listed just above. LeMarr also informs us that water heaters made in Japan and China are entering the U.S. market. Whenever we have updates to this water heater age and identification chart we'll post the latest version of it here.

How Long will My Water Heater Last? What Determines Water Heater Life?

Home inspectors typically expect a generic water heater to last about ten years. However all of us have found 20 year old models still going strong, while on occasion a newer model fails early.

The chronological age of a water heater (how long ago was it made) is hardly the only factor that determines how long the water heater will last. Here are some other factors that affect the life of a water heater:

Corrosivity of the water supply - more corrosive water may shorten the water heater life or the life of its anode. We discuss various tests of drinking water, including water corrosivity, at WATER TESTS, CONTAMINANTS, TREATMENT. In short, the chemistry of the water being heated affects the water heater life, and aggressive or corrosive water means shorter life for the water heater.
Mineral content in the water supply - if your water supply is high in minerals you may need a water softener - see WATER SOFTENERS & CONDITIONERS for details.
Water heater location - if the water heater is located where it is subject to flooding (as in our photo at above-left) the system is going to be damaged, short-lived, and possibly unsafe as well. Notice the multiple flood-lines on the water tank next to our client? Check out the shoes too. Don't wear white sneakers to inspect a crawl space.

Our next photo (left) shows how a tall water heater was shoe-horned into a low crawl space by digging out a pit to allow the tank to stand upright. This heater is also likely to be exposed to flooding.

We have also seen water heaters placed horizontally to fit into a tight crawl space - a possibly dangerous installation. Unless the manufacturer has specifically designed a water heater to mount horizontally there is risk that the tank or other components will not be properly supported and the system will be damaged and unsafe.

In sum, improper location or improper position of a water heater, such as mounting some water heaters horizontally or locating a water heater in a flood prone location or where it can't be properly serviced or vented can lead to early failure of the heater as well as voiding the manufacturer's warranty.

Water heater installation - improper installation of the water heater, or improper fuel or water piping connections or inadequate chimney venting on fossil-fuel fired water heaters can lead to safety problems or leaks and early heater failure.
Water heater maintenance - flushing mineral debris and dirt from a water heater can significantly extend its life as well as increase the quantity and temperature of domestic hot water the heater provides. If your water heater is making noises (see WATER HEATER NOISES) you probably need to de-scale the heater bottom. See WATER HEATER SCALE - De-Liming Procedure which are discussed at WATER HEATER NOISES.
Water heater anode replacement - the sacrificial anode protects a water heater tank from corrosion. Depending on the chemistry of your water supply, the anode may need to be replaced every few years or even more frequently. If suddenly your hot water (but not your cold water) smells like rotten eggs, the problem may be with a corroded sacrificial anode. See SEWER GAS ODORS and see Check the Sacrificial Anode & Dip Tube of Your Water Heater Tank
Water heater tank type - most water heaters use a glass or porcelain liner which, along with the sacrificial anode, help protect the tank from corrosion. The construction of the water tank, methods and materials used affect the life of the tank, burner, and controls. Look at the water heater warranty period; a longer warranty probably means a more durable water heater tank.
Quantity of hot water used - using more hot water increases the duty cycle of the water heater and exposes the tank to extra risk of corrosion. The temperature to which the water heater is required to heat the hot water may also be a factor in tank or burner or other water heater part life. The quantity of hot water used, which determines how hard it works, is called the duty cycle or level of usage of the water heater (more use = shorter life).
Not enough hot water? If your water heater seems to be working ok but you just never have enough hot water, see HOT WATER IMPROVEMENTS and HOT WATER QUANTITY IMPROVEMENT.
Water heater warranty periods - the warranty for a given model water heater is also a predictor of how long the manufacturer expects the tank to last. (A grouchy friend opined to the author that all of the tanks are the same, but the water heater price is higher on a water tank with a longer warranty period. We have not found data to support this view.) We discuss water heater warranties in more detail just below.

Also see Water Heater Life Expectancy Comparisons for a short list of other factors that determine the life expectancy of a water heater.

What are the Typical Terms of Water Heater Warranties

Type of water heater tank and water heater warranty - modern "glass lined" water tanks are coated to resist corrosion. The manufacturer's warranty is a clue to how long the company expects their water heater tank to last.

Typical water heater warranty periods for a water heater installed for use by a single family are 6-years, 9-years, or 12-years. But beware: if the water heater tank leaks and fails before the end of the warranty period, if the system has not been properly installed or maintained the warranty may be void. Water heater warranties typically indicate that the tank is warranted against leaks due to rust, corrosion, or chemical action of the water but the warranty will exclude a tank failure due to scale.

The warranty period of a water heater may be encoded in its model or serial number. For example Lochnivar water heaters include a model number prefix that determines whether the heater is warranted for six years or for ten years. If the water heater is in any other use than one-family residential, the heater is warranted for one-year on parts and three years on the tank itself.

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AGE of WATER HEATERS

Scott C. LeMarr has provided his file of keys to decode Water Heater Age from the data provided on the manufacturer's equipment labels. Mr. LeMarr is a professional home inspector, Certified Professional Inspector/President, MASTER Indoor Environmental Specialist (MIES). Vice President of Wisconsin NACHI. He and his company, Honest Home Inspections, LLC. can be reached at 262-424-5587 or by email to scott@honesthomeinspections.com
Carson Dunlop, Associates, Toronto, have provided us with (and we recommend) Carson Dunlop Weldon & Associates' Technical Reference Guide to manufacturer's model and serial number information for heating and cooling equipment ($69.00 U.S.). Technical Reference Guide, Carson Dunlop Weldon & Associates, Ltd., 120 Carlton St. Suite 407, Toronto, Ontario, M5A 4K2 Canada, ISBN 1-895585-90-2 165pp.
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
G.E. Water Heater warranties and other water heater information can be found online at geappliances.com
Lochnivar or some vendors of Lochnivar water heaters provide an online copy of its water heater warranty (01/26/2009)

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The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ^® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.

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How to Determine the Age of a Water Heater

Here is A Chart that Decodes the Date of Manufacture of a Hot Water Heater

How Long will My Water Heater Last? What Determines Water Heater Life?

What are the Typical Terms of Water Heater Warranties

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair