Rheem water heater (C) Daniel Friedman Find Water Heater Age or Manuals
Water Heater, Geyser, Cylinder, Calorifier Contacts & Water Heater Manuals

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Water heater age decoders, water heater manual sources:

In addition to details of how to de-code water heater age for all water heater brands we give six ways to determine the age of a water heater. We also discuss the conditions, maintenance, and factors that affect how long a water heater can be expected to last.

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? DECODING GUIDES for water heater age, 5 data tag decoding documents, books, methods. Geyser & cylinder warranties & water heater life.

We give contact information for water heater, geyser, cylinder, calorifier manufacturers and for water heater installation, operation, & troubleshooting manuals.

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.

Green links show where you are. © Copyright 2017, All Rights Reserved.

How to Determine the Age of a Water Heater

Rheem water heater (C) Daniel Friedman

Article Contents


WATER HEATER AGE DECODING GUIDES - six methods for figuring out the age of a water heater - listed just below:


Our photo above 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.

[Click to enlarge any image.]

Water Heater Age Decoding Charts & Tables: Six ways to find out how old your water heater actually is

1. Specific Water Heater Age Decoding Guides by Brand

Specific Water Heater Age Decoding Guides by Brand are given below in an alphabetical list starting at at WATER HEATER DECODING by BRAND - list of water heater brand names, manuals, contact information, found below in this article.

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.

Carson Dunlop Technical Reference Guide (C) Carson Dunlop AssociatesHow 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.

2. HVAC Data Tag Decoder Carson Dunlop Associates Technical Reference Guide HVAC & Water Heater Serial Number De-Coding Book

Carson Dunlop Associates 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.

3. Scott LeMarr's Water Heater Age Determination Chart

AO Smith water heater label shows age (C) Daniel FriedmanScott LeMarr has generously shared his free WATER HEATER AGE DETERMINATION CHART that decodes both furnace age and water heater age from label data.

Scott includes data for many brands of water heater, including hot water systems produced by the manufacturers listed just below. [PDF linked to return here. You can also use the "BACK" button on your browser to return to this page.


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.

Mr. LeMarr has also shared his FURNACE AGE DECODING CHART with InspectApedia readers.

You can also use the "BACK" button on your browser to return to this page.

4. Energy Label on Water Heaters or other Equipment Year May Help Decode the Equipment Age

Our photo (at above left) is from the A.O. Smith EnergySaver water heater in our laboratory. Enlarging this image you will see a date 12/26/02.

[Click to enlarge any image]

Scott points out that

On occasion there is a yellow "Energy" label on the unit and at the bottom (sometimes middle) will tell you what ANSI Spec it was built to or it may give you an estimated cost on a particular year. If it reads ANSI Spec 1994 that it would have to be 94 or newer typically these specs come out every 2-3 years.

5. Direct help from water heater manufacturers

For page speed & reader convenience we moved this topic to a separate article - at WATER HEATER COMPANIES by country: Australia, New Zealand, USA, UK etc

6. How to Decode Non-Standard, Unknown Water Heater Serial Numbers & Data Tags to Guess Water Heater Age

Rheem water heater label (C) Daniel FriedmanApproaches to finding the age of any water heater / cylinder / geyser are given here. If your water heater brand or trader name doesn't appear in the list at WATER HEATER DECODING by BRAND you can use this general data tag decoding guide.

  1. Find the data tag (as I've discussed above) that will allow us to decode the date of manufacture of the heater.

    Look for reasonable apparent year ecodings in the equipment serial number in format MM YY

    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.

    In a second water geyser age (cylinder age, water heater age) 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.

    General approach to decoding unfamiliar water heater serial numbers to get water heater date of manufacture

    Typically the manufacturer used

    a two digit month and two digit year,

    1 digit month that used alphabetic characters

    2 digit week (1-52) and 2 digit year

    WITH sometimes a plant ID code in the serial number, typically a letter, separating the numeric or other age and serial number digits.

    So if we have no other data, we look for a pattern that can decode to a reasonable year using those schemas.

    Using Rheem water heaters as an example many, not all, water heaters made by Rheem were sold under other brand names such as Montgomery Ward.

    Modern Rheem water heaters use a 10 digit code:

    MMYYX12345 where X is the plant code and 12345 a consecutive unique ID and of course MM YY are month and year.

Wards Signature 500 glass lined water heater geyser cylinder (C) InspectAPedia DP
  1. Find the installation and service manual for this particular water heater.

    Often the installation guide is stuck behind a pipe or overhead nearby. The manual may include a purchase of sale receipt, handwritten notes on installation date, or even lacking these, it will have a publication date that gives the earliest-likely manufacturing age of this specific heater.
  2. Note the age of the building where the heater (geyser, cylinder) is installed.
  3. Note the age of components used to install the heater such as its wiring and plumbing materials
  4. Contextual clues of water heater age: Note the age and location of the building. That will give us some context. Also note the age of remodeling or building changes.

    Here is an example commentary about water heater age we provided to a reader:

    Your Signature 500 electric water heater (or geyser or cylinder depending on where you live) looks like a much newer installation. I see light colored wood 2x studs (recent construction) and shiny copper electrical wiring at the ground connection at the heater top. Also I see the use of modern red PEX tubing used for the temperature/pressure relief valve discharge tube.

    Certainly the heater could be older than its present wiring and plumbing, but if those are any guide, this is not a very old unit.

    Depending on where you live we could get a more accurate estimation of the year of installation of the water heater plumbing as presently shown even before finding the heater's data tag (which I am betting is there somewhere). PEX surged in popluarity in the U.S. beginning around 2000.

    For example, in the United States, California, one of the last adopters, did not approve the use of PEX (cross-linked polyethylene tubing) for household plumbing until 2007 (on a case by case basis) and not until 2009 for all homes.

    More about PEX plumbing pipes used for building water supply and hot water heating applications can be read at PEX PIPING INFORMATION.

  5. Look around the heater for a water heater service tag, perhaps stuck in a floor joist or on a wall top nearby - that can give an idea when the heater was installed or may give that precise date.

Water Heater Age Decoding, Manufacturers, Manuals, Contact Information by Brand - alphabetical list

Bradford White water heater identification (C) Daniel FriedmanWhile the most complete water heater age de-coding charts and tables are in the book and PDF files we list above, here we also list water heater age or serial number decoding charts for particular water heater brands or products requested by readers.

Because some water heater manufacturers (such as American) produce heaters (or calorifiers or cylinders) sold under multiple brands, you may also find your water heater's age decoder by using your browser's On-Page Search feature (Ctrl-F or CMD-F).

For example, Ace, Apex, Aqua Temp, Aqua-Therm ... Tru-Value, Whirpool and more brand names are all produced and decoded by the American Water Heater Age Decoder.

If your water heater does not appear in this list you are welcome to contact us using the page top or bottom CONTACT link and we'll help reseach your question at no charge.

If the serial number in your water heater data tag format does not match what's given in each of these guides, see DATA TAG DECODING ADVICE for NON-STANDARD DATE CODES.

Aerco Gas Fired Water Heater Manuals

American brands Water Heater Age

Check the American water heater serial number, not the model number.

A TruFlo water heater was made by American (Tru-Test or Tru Value water heaters) or by U.S. Craftsmaster, then the age is encoded in the serial number as follows:


First two digits of the serial number are the year

Second two digits of the serial number are the week

Example: 9201nnnnn would translate as 1992, first week [i.e. January 1-7 in 1992]

American brand water heaters may be distributed under any of the following names:

Ace Hardware, Ace water heaters, American Hardware water heaters, America's Best, Apex Water Heaters, Aqua TempWater Heaters, Aqua Therm Water Heaters, Aquamatic water heaters, Best Water Heaters, Best DeluxeWater Heaters, Craftmaster Water Heaters, Champion water heaters, De-Limer Water Heaters, Deluxe Water Heaters, Eagle Water Heaters, Earl's Water Heaters, Envirotemp Water Heaters, Flame-Guard water heaters, Four-Most Water Heaters, GSW water heaters, Hotmaster Water Heaters, Hotstream Water Heaters, John Wood water heaters, King Water Heaters, King Clean water heaters, King Line water heaters, Lowes water heaters, Master Plumber Water Heaters, Mor-Flo Water heaters, Mor-Flo/American water heaters, Nationaline Water Heaters, Neptune Water Heaters, Penquin Water Heaters, Polaris water heaters, Premier water heaters, Prestige Water Heaters, PRO-Line Water Heaters, also Proline Plus water heaters, Quaker Water Heatersr, Quick-Flo Water Heaters, Raywall Water Heaters, Revere Water Heaters, Riviera Water Heaters, SABH Water heaters, Sands Water Heaters, Sentinal Water Heaters, Servistar Water Heaters, Shamrock Water Heaters, Special-Deluxe water heaters, Standard Brand Water Heaters, Super-Eagle Water Heaters, Super-Flo Water Heaters, Supreme Brand Water Heaters, Sure-Fire Water Heaters, Thoro-Clean Water Heaters, True-Test Water Heaters, Tru Value Hardware Water Heaters, U.S. Craftmaster Water Heaters, U.S. Supply Water Heaters, Whirlpool Brand Water Heaters, XCL Energy Water Heaters, Whirlpool water heaters.

Contact Information for American Brand Water Heaters

American water heater company history

American Water Heater was founded in 1996, based in Johnson City TN., GSW, a long-standing manufacturer or water heaters located in Canada and with operations in both Canada and the United States was the parent company of American Water Heater company from 2002 ro 2006.

On 3 April 2006, American Water Heater under the aegis of GSW was purchased by A. O. Smith Water Products Co.. The company also operates in Mexico, Nanjing China, and Veldhoven, Netherlands.

Also see

A.O. Smith Water Heater Age Decoding Tips

A.O. Smith Water Heater Age Determination - reader comment: (May 11, 2012) AO Smith employee said: To tell the age of any AO Smith water is the first 4 numbers.

The first 2 are the year and the second 2 are what week it is. I work in the Q.C. Department there and make the serial plates all the time. Hope this information helps some people out - A.O.S. employee.

Current date code: Ser# YYMM123456

Example 1: Ser# 9902123456 decodes to the year 1999 and the week 02 - or early January. This A.O. Smith water heater date of manufacture code has been used since 2008.

Previous date code: Ser#MYY123456

Example 2: Ser# B011234456 decodes to February 2001: the first letter encodes the month using A - N for January - December (the letter I is not used) and the second two digits encode the year.

Other AO Smith water heaters that may be sold under different brand names include Glascote water heaters, National water heaters & Perma-Glas water heaters.

Contact Information & Service Manuals for AO Smith Water Heaters

Bosch Water Heater Technical Support & Water Heater Manuals

Also see

Bradford White Water Heater Age Decoding Guide

Bradford White water heater age is encloded as two letters in water heater's serial number as follows:

Current Bradford White water heater date code format: YM234567...

First letter = year of manufacture

Beginning with A = 1964 or A = 1984 r for newer water heaters made after 2003, A = 2004

Ending with Z = 2003 or M = 2015 etc.

Second letter = month of manufacture

Later model water heaters may replace letters with an actual year and month encoding as numeric digits.

Beginning with A = January and ending with M = December

Example: Bradford White water heater serial number ZJnnnnnnn = 2003, September

Note: in the month code the company encodes the month in A - M and does not make use of letters I, O, Q, R, U or V)

Jetglas water heaters made by Bradford White use the following date enoding:

YM1234567 encoding the year and month alphabetically using A-M for month (skipping the letter I) and a series of year-series for alphabetic letters. A - 1983, B - 1984, C - 1986, D-1987, etc.

List of Bradford White Water Heater Brands

Bradford White water heaters, Jetglas water heaters

Contact Information for Bradford White Water Heaters

Chrysler AirTemp Water Heater Age Decoding Guide

Chrysler Air Temp Water Heater Age Query:  (Mar 16, 2012) Dan said: Need to find age of Chrysler Airtemp Gas Furnace: Model #4208-10, Ser #'s hard to read. Could be: Ser# 00584865, 06584865, or 0G584865 

Reply: best guess 1970.

From Carson Dunlop Associates comprehensive Technical Reference Guide

Chrysler Air Temp Products: see AirTemp and Fedders. In HVAC serial numbers the first digit is a key to the year of manufacture beginning with 1970. So SN# 42599229 would de-code to be manufactured in 1974

Contact information for Chrysler Air Temp

Envirotron - Envi-ro-Temp Water Heater Age Decoding Guide

Envirotron Water Heater Age Query: (Nov 7, 2011) Jackie said: I need warranty information also. Product #0726021 Serial #0214115365  model #GIF4034T3NV . It's an Envirotemp water heater. Need to know if it's still under warranty.

Reply: Year 2002, week 14. Details are at ENVIROTRON WATER HEATER AGE

Contact Information for Envirotron or Enviro-Temp water heaters:

Fowler Electric Water Heater Age Decoding

Fowler electric water heater ad (C) InspectApedia

Question: how to decode the age of a Fowler Electric Water Heater - Republic Thermo-Glas

2016/02/09 said:
Can you tell me the age of a water heater with Model number 52-E-LD-5 Serial number 41464? It has finally given out and needs to be replaced. I'm just curious about to how old it is. The information on the front says Republic Thermo-glas, and mfg. tag says Fowler Manufacturing which I understand is, or was, a division of Republic.
Thank you.


As I'm on assignment out of the U.S. I don't have Carson Dunlop's water heater age decoder at hand. Sorry. Fowler produced both electric and gas fired water heaters until the late 1960's.

But the Fowler Manufacturing's Republic Thermo-Glas is not a brand for which we have a decoding chart. I GUESS from what we know of the Fowler Water Heater company history and the serial number on your unit that it was made in April of 1964.

That's based on looking for a reasonable two digit year in the number and guessing that the manufacturing month precedes it.

Fowler: xxMYY

Fowler gas water heater patent (C) InspectApedia

Fowler electric water heaters are dated as early as 1917 and continued into the 1960's. Patent research and trademark research give us some of these dates as well as the originator, Paul L. Fowler who is cited his 1958 patent for a concentric gas and air burner for water heaters, U.S. Patent No. US2564358 A filed in 1947.

Republic Glass-lined "Thermo-Glas" rust resistant water heaters may have been a re-brand of Fowler products. Republic brand electric water heaters were sold at least into the 1960's based on a screen of advertrisements archived by Google. It's possible that the actual water heater tank was produced by Republic Steel Company that in turn was purchased by Rheem Manufacturing in the 1930's.

Republic Thermo-Glas water heater ad from ca 1955

General Electric Forced Air Furnace & Water Heater Age De-Coding Guide

QE Furnace Age Query:  (Nov 18, 2012) Lyn said: I am trying to determine the age of my electric f.a. furnace. It is a General Electric made in Toronto, Ontario.
The Serial number is Ser# 398 870 T21 
The model number is BWL730G172B.
If someone could please advise the age of my furnace, it would be greatly appreciated.
Thanking you in advance.

Reply: You've sent us a warm air heating system code not a water heater code. This article and comment page are for water heaters. For details on age determination for heating boilers & furances see AGE of HEATERS, BOILERS, FURNACES.

But I make this code as March 1998

For a complete guide to GE or General Electric HVAC and other equipment you will need to see the pages of data on GE found in Carson Dunlop Associates comprehensive Technical Reference Guide. Generally for GE water heaters the first one or two digits are the month and the next two the year of manufacture. So your heater was made in month 3 and in year 98 - March 1998.

Contact Information for General Electric Water Heaters

Giant Water Heater Age, Data Tags, & Manuals

Data tag details: pending; images of Giant water heater data tag wanted. Use our page bottom or top CONTACT link - Ed.

Question: where to find Giant brand water heater manuals

I am not sure I have come to the right place however are you able to tell me where I could find a 2006 Giant Electric Water Heater Manual for Model 172ETE-3F5m? - Anon in Toronto, Ontario, by private email 2016/07/27


Giant electric water heaters are manufactured by

Usines Giant Factories, Inc.,
40 Avenue Lesage
Montreal-East, Quebec, Canada H1B 5H3
Tel: 1-800-363-9354


The company has a "literature request" page at

The Giant 172 series water heaters, aka "Super Cascade" are
described by
and by

The company's engineering data sheet tells us that a Giant water heater Model 172ETE - 3F5m is not listed but the company currently lists a 172ETE-3F7M as a 74 gallon (279L) or 61 imperial gallon electric water heater using 4500W 240V.

Here is the company's link to the Installation Manual for the Giant 17E heaters:

I am attaching a link to a typical Giant electric water heater installation and operation manual [PDF about 16MB]

GSW Hot Water Heater Age De-Coding Procedure - Quel âge a votre chauffe-eau?

GSW Water Heater Age Query: (Mar 1, 2013) Lee Harding said: I'm trying to determine the age of my GSW hot water heater. Model 6G505DE1
Serial # 50704 535391. I can't tell from these numbers.

Reply: best guess: week 50 of year 1970

Normally the first two digits of the serial number give the GSW heater's year of manufacture. Your serial numbers don't match this system, perhaps because of wear or smearing or heater particulars. From your serial number we'd guess week 50 year 1970 - which seems a bit antique. Re-check that you're really seeing a 50 in the first two digit positions.

For GSW water heaters manufactured before 2008 the heater the age is encoded as the first four digits of the serial number as two digits of year followed by two digits of month.


For GSW water heaters produced after 2008 the water heater age is also encoded in the first four digits of the serial number but as two digits of year followed by a two-digit week number (weeks 01-52).


Contact information for GSW Water Heaters

From GSW's website (2017), GSW produces for-sale as well as rental-water heaters in Canada.

Hi Test Hoyt Water Heater Age De-Coding Tips

Hoyt Water Heater Age Query: (Nov 5, 2012) Alexandra said: I am trying to find the age of my Hi Test Hoyt water heater. The Serial is SN A87RNH1373190, model A40HM

Reply: best guess 1987. Details along with contact information for Hoyt water heaters are at HOYT WATER HEATER AGE

Hotpoint Water Heater Data Tag Decoding & Water Heater Age

Data tag for Hotpoint water heater shows model and serial number encoding age and features (C) JG

[Click to enlarge any image]

Reader question: can we move this Hotpoint water heater over an inch?

... here is a photo of my hot water heater data: here is a photo of my hot water heater data:

It still works fine. I don't understand how it can produce 50 gallons for its size. We wanted to move it over 1 inch to accommodate a new washing machine but it appears bolted to the floor. I hate to mess with something that appears to be working fine but worry about the day that it stops. - Anonymous by private email 2016/07/19

Reply: Hotpoint water heater Serial Number decode:

Hotpoint water heaters prior to about 1980 such as those bearing the data tag shown above use serial numbers in the format AAAWWYY 

Your Hotpoint water heater data tag serial number looks like 1TU2270 leading me to guess that the last two digits may be the year of manufacture (70 in this example). The preceding two digits (22 in this example) may be the week of manufacture.

Looks like this Hotpoint water heater or calorifier was made in 1970? Is that possible?

Later Hotpoint water heaters, manufactured by Rheem, use serial numbers in the format AAMMYY123456 begin with two letters (in position AA)

then follow with two digits of production month (in position MM and numbered 01-12)

followed by two digits of production year in position YY.

Hotpoint Catalog Number decode:

The Hotpoint water heating calorifier or cylinder Catalong No. (or model number) is 100WBSC521035, leading me to guess that the catalog number, giving water heater features, decodes as follows:

Last four digits give the wattage of the top and bottom heating element as 35 = 3500 Watts, and 10 = 1000 Watts.

The data tag also indicates

Bolted to floor - sounds as if you're in an earthquake zone. A bit of unbolting, re-plumbing, and then re-securing the heater to the structure would be required. A bit of work but perhaps justified if that's where you need to place your new washing machine.

Contact Hotpoint Appliances

Hoytt Water Heaters

Hydraulics Institute Heaters

Hydraulics encodes the date of manufacture as two digits of week and two of year in positions 1-4 of the serial number


Intertherm Water Heater Age Decoding Guide

Intertherm Water Heater Age Query: Hi, can you tell me the date an Intertherm water heater was made?

Model #IHMS960E4 - Serial #K07433029

Reply: best guess 1974. Details and contact information for Intertherm water heaters are at INTERTHERM WATER HEATER AGE

John Wood Water Heaters Age & Manuals JW Water Heaters

Contact: GSW Water Heating Company, 5999 Hill St. West, Fergus, Ontario N1M 2X1 Canada

Lochinvar Water Heater Age & Manuals

Lochinvar sold water heaters under these brands: Lochinvar, Energy Saver water heaters, Golden Knight Water Heaters, and Knight Water Heaters.

YM123456 where Y encodes the year equating A to 1964 or 1984 or 2004 etc. and M encodes the month using A - N for January - December (the letters I O Q R U V are not used in these coding schemes)

For more about Lochinvar Water Heaters - see BRADFORD WHITE

Marathon water heater age decoding from serial number

On Marathon water heaters the age is encoded as the first four digits of the serial number.


Contact Information for Marathon water heaters

Marathon water heaters are currently (2015) a Rheem product.

De-code Older Montgomery Ward water heater serial numbers in format Ser# TE22780

Wards Water Heater Age Query: 01/24/2014: G M Wagner said: Montgomery Ward Electric Water Heater-Model 94-SHT-2861A, Serial # TE22780' . Would you please tell me how old it is. Remodeling the basement and finally putting in a new one. thank you.

Reply: 1980. Details and contact information for Wards water heaters are at MONTGOMERY WARD WATER HEATER AGE

Reliance Water Heater Manuals & Age Decoding

Reliance Water Heater company produces both gas and electric water heaters in a range of sizes and models for residential use, mobile home use, and point of use applications. Models also vary by warranty period including 6-year, 9-year, 12-year warranties.

Reliance also produces a wide range of tankless water heaters in indoor and outdoor models, ultra low NOx models, Non-conden sing models, and set-up for burning either propane or natural gas.

Notice: the reliance water heater manuals listed here are a representative subset of the enormous number of electric, natural gas, propane gas water heaters with various features. In the Reliance Water Heater Company contact information below we provide a link to the company's current list of all of their water heater models.

Electric Water Heater Manuals from Reliance Water Heater Company

Natural Gas Fired Water Heater Manuals from Reliance Water Heater Company

Propane Gas Fired Water Heaters from Reliance

Tankless Water Heaters From Reliance

Contact the Reliance Water Heater Company

Reliance Water Heater Company, 500 Tennessee Waltz Parkway, Ashland City TN 37015 USA,

Tel: 800-644-9306 Website: Reliance Water Heater

Parts: TEL 1-800-365-4054 (You will need model and serial number as well as the item number and part description from your water heater's manual)

Rheem water heater age determination & serial number decoding

Modern Rheem water heaters use a 10 digit code:

MMYYX12345 where X is the plant code and 12345 a consecutive unique ID and of course MM YY are month and year.

We discuss Rheem-manufactured water heater date codes in more detail below.

Rheem produced water heaters sold under many other brands including

ABS water heaters, Aqua Therm water heaters, Cimarron water heaters, Citation water heaters, Coast to Coast water heaters, Energy Master General Electric water heaters, Intertherm & Miller water heaters, Lowe's water heaters, Mainstream water heaters, Montgomery Ward water heaters (see MONTGOMERY WARD WATER HEATER AGE), Professional water heaters, Rheem water heaters, Rheem/Ruud water heaters, Richmond water heaters, Ruud water heaters, Servi-Star water heaters, True-Value water heaters, Vanguard water heaters,

Reader question:

(Oct 26, 2012) meme said:

how many years should a Rheem hot water cylinder last


Meme, Rheem's warranty period for hot water heating equipment (cylinders, geysers) varies by product series but is typically 5-10 years.

You will need your product name and model number as well as serial number to look up the exact information for your unit. For example, the HPWH has a 10-year tank leak warranty and a 10-year parts warranty and a first year in-home labor warranty is included as well.

Some Rheem heating equipment such as gas furnaces includes longer periods for the heat exchanger, such as 20 years or "lifetime".

You should be sure to register your hot water cylinder at the company's website as that will aid in any future warranty claim. You can call Rheem directly for help. In North America call 1-800-621-5622 and listen for the prompt to take you to warranty information provided by the company

Rhyeem serial numbers on modern heating equipment can be decoded by mapping the corresponding digits of the unit's serial number as follows:



MM = month of manufacture

YY = year of manufacture

P = plant identifying code

nnnn = a consecutive serial number for your individual unit

Rheem water heaters that may be sold under other brand names include

AquaTherm water heaters, General Electric water heaters, Hotpoint water heaters, Professional Brand water heaters, Vanguard water heaters & Western Auto water heaters.

- retrieved 6/24/2014

Contact information for Rheem Water Heaters

Richmond Water Heater Age Decoder

Richmond water heaters include the water heater's month and year of manufacture in the first four digits of the serial number as in this example:


Rinnai Water Heater Age Decoder

Rinnai water heaters encode the manufacturing date in the first four digits of the heater's serial number, as YY MM for Year and Month

Ruud Water Heater Age Decoding

Ruud water heater serial numbers encode the heater age in the first four digits of the serial number as


Other Ruud water heaters that may be sold under a different brand name include

Professional Water Heaters and Richmond Water Heaters.

Contact information for Ruud Water Heaters, Inc:

State Water Heater Age Decoding Information

State water heaters, produced by State Industries, encode the age in the first three positions of the State water heater serial number as


Where M is a one-letter month code, encoded corresponding to A = January through M = December and the second two digits are the numeric year.

On some State water heaterrs age is encoded in the firsrt four positions of the State or Apollo Comfort Products Water Heater serial number as

MMYYnnnnn such as 0910123456 where the heater was made September 2010.

Note that I've seen some guides claiming the opposite encoding, that is YYMMnnnnn

Other water heater brands by State or using the same format include

Apollo Comfort Products water heaters

State Industries produced water heaters sold under these brand names

Ace Water Heaters, Ambassador water heaters, Barnett water heaters, Century water heaters, Crosley water heaters, Energy Stretcher water heaters, Freedom water heaters, Hardware House water heaters, Kenmore water heaters, Master Plubmer water heaters, Master Plumber True5 water heaters, Mission water heaters, National line Water heaters, also Nationaline water heaters, Patriot water heaters, Penfield water heaters, President water heaters, Regency water heaters, Reliance water heaters, Sears water heaters, State Industries, State water heaters, The Plumbery water heaters, Thermo-king water heaters, Top Line water heaters

Contact information for State Water Heaters, Inc.

U.S. Craftsmaster Water Heater Age Decoder

U.S. Craftsmaster water heater age is usually encoded in the first four digits of the heater's serial number as in this example:


Where WW is the week number (weeks 01 through 52) and of course YY indicates the last two digits of the year of manufacture.

U.S. Craftsmaster is an indpendent water heater manufacturer whose heaters have been sold under the following trade names or brand names

Ace Water Heaters, Ace Hardware Water Heaters, American Hardware Water Heaters, America's Best Water Heaters, Apex Water Heaters, Aqua Temp Water Heaters, Aqua Therm Water Heaters, Aquamatic Water Heaters, Best Water Heaters, Best Deluxe Water Heaters, Craftmaster Water Heaters, De-Limer Water Heaters, Deluxe, Eagle Water Heaters, The Earl's Energy Conservation Water Heater, The Earl's Energy Saver Plus Water Heaters, Envirotemp Water Heaters, Four Most Water Heaters, Hotmaster Water Heaters, Hotstream Water Heaters, King-Kleen Water Heaters, King-Line Water Heaters, Master Plumber Water Heaters, Nationaline Water Heaters, Neptune Water Heaters, Penquin Water Heaters, Prestige Water Heaters, Pro-Line Water Heaters, Pro-Line Plus Water Heaters, Quaker Water Heaters, Quick-Flo Water Heaters, Raywall Water Heaters, Revere Water Heaters, Riviera Water Heaters, Sands Water Heaters, Sentinal Water Heaters, Sentinel Water Heaters, Servistar Water Heaters, Shamrock Water Heaters, Special Deluxe Water Heaters, Standard Water Heaters, Supereagle Water Heaters, Super-Flo Water Heaters, Supreme Water Heaters, Sure-Fire Water Heaters, Thoro-Clean Water Heaters, True-Test Water Heaters, Tru Value Water Heaters, Tru Value Hardware Water Heaters, U.S. Craftmaster Water Heaters, U.S. Supply Water Heaters, Whirlpool Water Heaters, XCL Energy Saver Water Heaters

Watts Controls for Water Heaters

Watts S210-5 automatic thermostatic gas water heater shutoff valve - at InspectApedia.comDetails about automatic gas-shutoffs on gas water heaters are at AUTOMATIC GAS WATER HEATER SHUTOFF

Weil McLain Heater Age De-Coding Guide

Weil McLain Heater Age Query:  (Oct 25, 2012) carl said: how do you find an age of a Weil Mclain GV 3 Gold serial no cp 3406659

Reply: this looks like you have sent us a heating boiler brand and model number not a domestic water heater. Quoting product literature:

The Weil McLain GV boiler is a high efficiency, gas-fired direct vent water boiler with cast iron sections.

Using sealed combustion technology, the boiler reduces energy usage by eliminating air infiltration. The GV boiler is easy to install and service, and is useful for a wide variety of applications including residential, light commercial, multiple boilers, indirect-fired water heating, and radiant heating.

From Carson Dunlop Associates Technical Reference Guide, the most complete HVAC and water heater age decoding guide I've got (provided courtesy of CDA), Weil McLain heating boiler serial numbers beginning with 34nnnn were manufactured between 1998 and 2000.

This article and comment page are for water heaters. For details on age determination for heating boilers & furances

Watch out: for other Weil McLain boiler numbers one needs to consult the Guide cited above, as the encoding of serial numbers does not afford a formulaic de-code procedure. For example Weil McLain boiler serial numbers beginning with 32nnnnn were made beginning in 1997.

Contact information for Weil McLain heating equipment

Williamson Water Heater Manuals

What Determines Water Heater Life?

Flooded Water Heater (C) Daniel Friedman

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.

Details about water heater life expectancy: We have expanded and moved this topic to WATER HEATER LIFE

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 warranty coverage for the geyser or water heater for

Water Heater Performance Data


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