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Kenmore, WA
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[#1] Posted: Feb 03 2006 - 07:16:05 AM |  |  |
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Though water heaters are relatively inexpensive compared to the price of a house, repairs for the damage caused when one suddenly has a catastrophic failure is likely to be expensive. This is the reason many inspectors want to at least be able to give their client some idea of how old the device is and when it would be a good idea to start considering replacement.
So, what exactly is the absolute maximum service life to expect? It varies from place to place and is affected by the quality of the product, minerals/chemicals in water, the amount of maintenance the water heater receives and usage. In other words, there is no set in concrete maximum expected service life. In fact, two neighbors with exactly the same brand of water heater installed on exactly the same day on the same street in identical houses can have completely different experiences. In some parts of the country it is normal to expect between 10 and 15 years, while in others a homeowner is lucky if the water heater lasts 10 years.
The manufacturing date is coded into the serial number of water heaters and, since there are more than 100 different brands of water heaer in this country, the thought of trying to memorize every single serial number code at first seems impossible. Impossible that is, until one realizes that only six manufacturers produce those 100+ brands and some share the same basic method for coding, making the task of memorizing the coding methods far less formidable. In this article I'll explain the coding method used by each of the six major manufacturers. At the end of the article, there's a link to a handy decoding chart in TIJ's downloads library.
American Water Heater Company
American Water Heater Company, manufacturer of 52 separate brands of water heaters, uses a 10-digit serial number with a year/week code in the first four digits of the serial number. The year of is the first two digits followed by the two digit week of the year. For example,the serial number 0602****** indicates that the water heater was manufactured the second week of 2006. A complete list of brands manufactured by American is contained in the decoder chart linked to this article.
A.O. Smith Corporation
A.O. Smith Corporation, manufactures three brands of water heaters - A.O. Smith, Glascote and Perma-Glas - and uses a 10-digit serial number with a letter-month/year code in the second third and fourth digits of the serial number. With this system, the letters A to M, excluding the letter I, are used to designate the months 1 to 12 followed by the two digit year. For example,*H06****** would indicate that the water heater was manufactured in August 2006.
Bradford-White Corporation
Bradford-White manufactures two brands of water heater - Bradford-White and Jetglas - and uses a 9-digit letter/number code with two letters signifying the year and month of manufacturer. The letters I, O, Q, R, U, and V are skipped to produce 20-year cycles. These cycles began in 1964 with the letter A, therefore the letter A in the first position of a B-W serial number can represent the years 1964, 1984 or 2004. B-W's second letter corresponds to the month of the year as with the A.O. Smith example above.
Prior to 1973, the month letter was placed at the end of the 9-digit serial number but from 1973 on it has been in the second position. For example, the serial number B********D indicates the water heater was manufactured in April of 1965 but the serial number BD******* can indicate that it was manufactured in April of 1985 or 2005. The trick is being able to distinguish the age of water heaters with the same date codes manufactured after 1973. Fortunately, most home inspectors can do this easily simply by checking the large yellow energy usage tag on the unit to see which ANSI date is posted there. There is one exception to B-W's serial number code that was caused by a computer glitch when some units were manufactured with a serial number beginning with OA - O being one of the numbers that is not used. Any found with a serial number beginning with OA will have been manufactured in January of 1997.
Lochinvar Corporation
Lochinvar Corporation only manufactures four brands of water heater - Lochinvar, Energy Saver, Golden Knight and Knight - and uses the identical dating code system used by Bradford-White Corporation.
Rheem Corporation
Rheem Corporation manufactures 20 different brands of water heater and uses two different serial number series - one that is all numbers and the other which is both letters and numbers. However, the date code is based on the first 4 digits of the serial number, which signify the month followed by the year, the letter, which is in the 5th position, doesn't need to be considered. For example, any Rheem manufactured product bearing the serial number 0794****** or 0794F***** will have been manufactured in July of 1994.
State Industries
State Industries manufactures 23 separate brands of water heater, including the Kenmore(Sears) brand, and uses a letter-month/year serial number code similar to the A.O.Smith model with the letter signifying the month, followed by a number for the year. The difference is that with these the code is in the first three positions of the serial number therefore a serial number C05******* indicates that the water heater was manufactured in March of 2005.
There are other brands of water heaters being sold in this country that are not made by one of these 6 manufacturers. However, these 100+ brands are supposed to comprise the overwhelming majority of residential water heaters sold in this country today. Once one understands how these serial numbers work and learns to recognize each of the six manufacturer's individual patterns, it's much easier to feel confident that he or she is providing the customer the correct information about the age of the appliance.
To download the newly revised decoder chart, click here
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West Vancouver, BC
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 Understanding Water Heater Date Codes
[#2] Posted: Feb 07 2006 - 7:09:50 PM | | |
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Thanks for the great information.
Do you have any information on the John Woods or John Woods Pro brand?
These may only be Canadian brands, but I can't find any written information.
Thanks .... Sean
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Kenmore, WA
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Understanding Water Heater Date Codes
[#3] Posted: Feb 07 2006 - 7:48:42 PM | | |
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Hi,
Well, it took me a few minutes to figure out but I think I've got it. Believe it or not, it was a CPSC recall that helped me do it. There is a recall notice for controls on GSW (John Woods) water heaters that involve those sold from February 2002 to April 2003 and it involves GSW water heaters with serial numbers from 0202694162 to 0304507825 (underlining is mine).
Based on that, I've surmised that they use a two digit year followed by a two digit month so the 0202 in that first serial number equals Feb 2002 and the 0304 in that second number equals Apr 2003, which is exactly what the recall says. That should do it for you.
Looks like maybe I have to start compiling a list of Canadian brands as well. Hey you Canadian folks, send me some Canadian brand names and examples of their serial numbers so I can begin compiling a chart for Canada too.
ONE TEAM - ONE FIGHT!!!
Mike
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West Vancouver, BC
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Understanding Water Heater Date Codes
[#4] Posted: Feb 07 2006 - 9:15:49 PM | | |
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Thanks for the speedy info. I will have a look when I get back home.
I had always heard that the year / month coding had stopped in 2000, but you have proved that wrong. As for the Canadian brands that I routinely see......
John Woods 90%
Sears/Kenmore 5%
Other 5%
They must have some good marketing up here.
Thanks again for the information.
Sean O'Brien
GVK Home Inspections Ltd.
604-839-4301
gvk@shaw.ca
www.gvkhomeinspections.ca
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Pahrump, NV
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Understanding Water Heater Date Codes
[#5] Posted: Feb 10 2006 - 06:02:04 AM | | |
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Mike,
Good information, I really like the decoding chart.
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Monte Lunde CCI, CCPM, CRI
VCSI
www.vikingconstructionservices.com |
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Editor - TIJ
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Kenmore, WA
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Understanding Water Heater Date Codes
[#6] Posted: Feb 13 2006 - 7:28:54 PM | | |
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Hi All,
I've revised the code chart to make it a little easier to understand and in the next day or two will be replacing the one linked above with the new chart and that one will show the grid lines better. In the meantime, I've had such a good response to this one that I've decided to try and do something similar for heating systems and I'm looking for help from everyone. What I need is pictures of serial number plates for various manufacturers along with an explanation, if you have one, of how they are coded. If you don't have photos but can write out the code like I did on the chart, say ****A95**** or something similar I'd appreciate it. If you're willing to help, send whatever you've got to hausdok@msn.com and I'll see if I can create a similar chart for HVAC systems.
ONE TEAM - ONE FIGHT!!!
Mike
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Albuquerque, NM
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 Understanding Water Heater Date Codes
[#7] Posted: Aug 02 2009 - 8:27:06 PM | | |
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Hi there, I came across this article while Googling for info on how to tell how old a water heater is. It's so confusing that it had me thinking it was from 1994 and by using the info I found on this post I found out it's actually from 2007!!!! That's a HUGE difference. So I just had to drop a line and say Thank you very much.
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Zephyr Cove, NV
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Understanding Water Heater Date Codes
[#8] Posted: Sep 01 2009 - 2:40:45 PM | | |
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I have a Gas Water Heater that states it was manufactured by State Stove and Manufacturing Co in Henderson, NV. The Model# is C4 40 TMH. The serial# is K75100124. Does this mean the water heater was manufactured in October of 1975? The reason I ask is that my gas bills are high in the summer months and when we take showers the hot water only lasts about 10 minutes. I spoke to the gas company and they said the problem is likely the water heater. The only other gas appliances we have are the furnace (which isn't used in the summer) and a gas stove (which isn't used that much in the summer because I BBQ). Should the water heater be replaced?
Thank You
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Editor - TIJ
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Kenmore, WA
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Understanding Water Heater Date Codes
[#9] Posted: Sep 01 2009 - 3:46:38 PM | | |
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Hi,
Yes, it's very old - 34 years (K is September, not October (They don't use the letter I). Those things have an expected service life of about 10 to 15 years from the date of installation when properly cared for. It sounds like you've probably either lost one element or the dip tube has broken off - either way, it should have been replaced a couple of decades ago.
ONE TEAM - ONE FIGHT!!!
Mike
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Associate Editor - TIJ
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Editor - TIJ
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Kenmore, WA
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Understanding Water Heater Date Codes
[#11] Posted: Sep 01 2009 - 4:27:18 PM | | |
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Jeez,
I must be getting black holes in my reading to have missed that. Crimeny, how embarrassing. I just crapped my Depends. 
ONE TEAM - ONE FIGHT!!!
Mike
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Associate Editor - TIJ
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sioux city, iowa
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Understanding Water Heater Date Codes
[#13] Posted: Mar 16 2010 - 05:33:58 AM | | |
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I clicked on that link and found Furnace info but not Water Heater, my computer skills aren't great so i have to ask, thanks for any help.
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Understanding Water Heater Date Codes
