Ao Smith Water Heater Age

  • POST a QUESTION or COMMENT about how to find out the age of an AO Smith water heater

Smith Model Numbers. AO Smith rating plates look a little different, but have all the same info. Their date decoding is a little different. AO Smith puts the year first (1991), and the month second (07, or JULY). It’s a little harder to find the info on the AO Smith plate, but it’s all there! American Water Heater Model Numbers.

  • Determine the age of your Tucson water heater by learning how to find and decode data on the water heater. AO Smith and American.
  • Take an inside look at the A.O. Smith Vertex Water Heater assembly. After watching this you'll agree that our water heaters are top quality, and they're made.

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A.O. Smith Water heater age decode key & water heater manual sources.

Age decoding guid for water AO Smith water heaters, manuals, repair & maintenance guides.

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

We include a table of common error codes given on some models of A.O. Smith water heaters.

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.

We also provide a MASTER INDEX to this topic, or you can try the page top or bottom SEARCH BOX as a quick way to find information you need.

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 AO Smith water heater date code

Ser# YYWW123456 example 1604123456 decodes to YY=Year=2016 and WW=Week No. 04 of that year.

However on some AO Smith water heaters, particularly older models, you'll see a confusion of letters and numbers in the serial number that may be decoded into manufacturing date as shown below.

Older AO Smith water heater date codes

Ser# YYWW123456 - exampl: Ser# 9902123456 decodes to year 1999 and the week 02 - or early January. This A.O. Smith water heater date of manufacture code has been used since 2008.

Ser# MMYY1234567 - example: Ser# 03991234567 decodes to March 1999 this older style AO Smith water heater date code decodes as shown where MM = month and YY = 2 digit year.

Ser# MYY1234567 - example Ser# B0112344567 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.

Ser# FB00A123456 decodes to F=Factory code, B=month code using A - N for January - December (the letter I is not used) and the next two digits encode the year.
- example: Ser# GB92-03123456-789 decodes to Factory ID=G, Month=B or February, Year=92 or 1992.

Ser# N69-C-YY-12345 decodes provide year in the pair of digits shown as YY - found on water heaters from the 1970s

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

Ao Smith Water Heater Age

Contact Information & Service Manuals for AO Smith Water Heaters

Photo: A.O. Smith water heater data tag detail showing the water heater serial number

A.O. Smith water heaters are also sold under these brand names:

Glascote Water Heaters; PermaGlas water heaters

  • Contact: A.O. Smith Water Products, A. O. Smith Water Products500 Tennessee Waltz ParkwayAshland City, TN 37015USA, Tel: 800-527-1953.
    Website: http://www.hotwater.com/water-heaters/ - readers can find their type and model of AOS water heater and then find all of the documents concerning that model
    AO Smith water heater manufacaturer's water heater age page: https://www.aosmithinternational.com/manufacturing-date-device/
    A. O. Smith Corporation is one of the world's leading manufacturers of residential and commercial water heaters and boilers, offering a comprehensive product line featuring the best-known brands in North America, China, and India.
    The company was founded in 1874 in Milwaukee, Wisconsin where today the company is headquartered.
    - retrieved 2018/02/23, original source: https://www.aosmith.com/about/

Photos: Above: an A.O. Smith water heater installed, and the product packaging label data for that new AOS electric water heater.

Below: the data tag for this new A.O. Smith electric water heater.

The serial number for this A.O. Smith water heater is ME98-0041362-917

I decode this to E = May and 98 = 1998. We purchased this water heater as new old stock in 2015 - it was the last heater of this model series in stock at the local Poughkeepsie supplier.

[Click to enlarge any image]

AO Smith Water Heater Manuals & Troubleshooting Guides

  • A.O. Smith CONDENSING WATER HEATER TROUBLESHOOTING GUIDE [PDF], (2011) A.O. Smith Water Products Company500 Tennessee Waltz ParkwayAshland City, TN 37015Toll Free: 1‐877‐737‐2840
  • A.O. Smith PROMAX® ELECTRIC WATER HEATER 30 GALLON MANUAL [PDF] ProMax® electric water heaters for ProLine® water heater models ENT-30 ENT-40 ENTB-50 ENT-50 ENT-55 ENSB-30 ENS-30 ENS-40 ENS-50 ENLB-30 ENL-30 ENLB-40 ENL-40
  • A.O. Smith PROLINE® ELECTRIC WATER HEATER [PDF] ProLine® electric water heaters
  • A.O. Smith PROLINE® 50 Gallon LOWBOY MOBILE HOME WATER HEATER MANUAL [PDF] Proline Electric water heaters for models MHEW2-30L-035DV MHEW2-30H-035DV MHEW2-40R-035DV MHEW2-30L-030DV MHEW2-30H-030DV MHEW2-40R-030DV
  • A.O. Smith RESIDENTIAL GAS & ELECTRIC WATER HEATER SERVICE HANDBOOK [PDF] retrieved 2017/11/17, original source: https://www.hotwater.com/lit/training/320991-000.pdf
    This manual covers residential gas fired water heaters that are atmospherically vented and use a thermocouple as their electrical source, and residential electric water heaters having one or two heating elements and common wiring configurations.
    Excerpt:
    The information contained in this handbook is designed to answer commonly faced situations encountered in the operation of the Residential Gas and Electric product line and is not meant to be all-inclusive.
    If you are experiencing a problem not covered in this handbook, please contact the A.O. Smith Technical Information Center at 1-800-527-1953 or your local A.O. Smith Water Products Company representative for further assistance.
    Additional information is also available on the web site www.aosmithwaterheaters.com. This handbook is intended for use by licensed plumbing professionals and reference should be made to the instructional manual accompanying the product.
    This handbook contains supplemental information to the Residential Gas and Electric instructional manual.
  • AO SMITH GAS & ELECTRIC WATER HEATER SERVICE MANUAL [PDF] retrieved 2018/04/10, original source: AO Smith www.hotwater.com/lit/training/320991-000.pdf
  • AO SMITH ELECTRIC WATER HEATER WIRING INSTRUCTIONS [PDF] A. O. Smith Water Products 500 Tennessee Waltz Parkway Ashland City, TN 37015 USA Phone: 800-527-1953 A. O. Smith products, technical support, warranty or service needs Website: www.hotwater.com
  • A.O. Smith, INSTRUCTION MANUAL, GAS WATER HEATERS MODEL GDV GDVT [PDF] A.O. Smith Water Heaters, 500 Tennessee Waltz Parkway, Ashland City, TN 37015 USA, Tel: 1-800-433-2545 Website: www.aosmithwaterheaters.com Email: [email protected] 2018/05/04, original source: www.hotwater.com/lit/im/res_gas/186589-000.pdf
  • AO SMITH GAS WATER HEATER OWNERS MANUAL [PDF]
  • AO SMITH GAS WATER HEATER PARTS LIST [PDF]
  • AOS Bulletin 13 WATER HEATER MINERAL BUILD-UP [PDF] retrieved 2017/11/17 original source: https://www.hotwater.com/lit/bulletin/bulletin13.pdf
  • AOS Bulletin 14 HEATER ALUMINUM HYDROXIDE [PDF] retrieved 2017/11/17 original source: https://www.hotwater.com/lit/bulletin/bulletin14.pdf
  • AOS Bulletin 15 HEATER CONDENSATION [PDF] retrieved 2017/11/17 original source: https://www.hotwater.com/lit/bulletin/bulletin15.pdf
  • AO SMITH WATER HEATER DE-LIMING INSTRUCTIONS [PDF]
  • AOS Bulletin 11: WATER HEATER WATER HAMMER [PDF] retrieved 2017/11/17, original source: https://www.hotwater.com/lit/bulletin/bulletin11.pdf
  • AOS Bulletin 51 WATER HEATER PUDDLE ON FLOOR [at the water heater] [PDF] retrieved 2017/11/17, original source: https://www.hotwater.com/lit/bulletin/bulletin51.pdf
    and see AOS Bulletin 15 given above
  • Also see TAKAGI WATER HEATER MANUALS, AGE, ERROR CODES

AO Smith Water Heater Standard Error Codes

If your AO Smith condensing water heater code includes a circuit board or remote control it can show an error code. Contact your plumber or AO Smith technical support at the location given above in this article.

Watch out: your water heater model may use different codes or may provide error codes that are not given here. Therefore you'll want to consult the manual for your specific heater.

Table of AO Smith Condensing Water Heater Error Codes

Error CodeMeaning
005

Improper combustion, warning for 991 error.

Watch out: this is an unsafe condition risking CO hazards.

031Wrong dip switch setting, possibly LP gas set when the fuel is Natural gas, or vice versa
070Computer board failure - see 701
072False flame detected - see 721
074Remote control problem - see 741, 751
099

Improper combustion - see 991

Watch out: this is an unsafe condition risking CO hazards.

101

Improper combustion.

Watch out: this is an unsafe condition.

Look for a blocked flue or chimney (or downdrafts in the chimney) or a problem with the draft inducer fan.

111

Ignition failure; the burners do not light.

Check for a bad igniter, flame sensor, gas valve. Check for gas supply. Check for a blown fuse on the circuit board.

121Burner flame lost. See code 111 above.
311

Output thermistor failure.

Check the thermistor and its wires on the heat exchanger. Replace the thermistor if you don't see a loose or disconnected wire.

321

Input thermistor failure.

Check the thermistor and its wires at the water inlet. Replace the thermistor if you don't see a loose or disconnected wire.

391

Air-fuel ratio rod failure.

Check wire connections and if no loose wire, replace teh AFR rod.

441

Inlet filter clogged, water flow problem.

Also check for loose wire connections.

510Gas valve failure. Inadequate gas pressure or flow.
551

Gas solenoid valve failure.

Check gas supply and if no problem the solenoid needs replacement.

661

Water heater fan motor failure.

Check for loose wires and if none found the fan needs replacement.

701

Computer board failure;

check for loose wires, electrical power supply, signs of damage to the board such as black or brown marks indicating overheating or burned

711

Gas solenoid valve drive circuit failure.

See Codes 111 & 121

721

False flame detected. Blinks 6 times.

Check for condensate accumulation, blocked or missing condensate drain, condensate leaks.

741

Remote control not communicating with the water heater, check remote batteries,

check remote sensor wiring, remote control access line of sight.

751Remote control not communicating with the water heater, check remote batteries, line of sight.
761

Easy Link system communication failure.

Check connection between multiple water heaters.

991

Improper gas combustion. Blinks 5 times.

Watch out: this is an unsafe condition risking CO hazards.
If this indicator is on from first activation of the heater it may not be properly adjusted for the elevation at which the heater is installed.

Check for blocked exhaust flue or under-sized exhaust flue.

Check for debris clogging the gas burner or for a failed or blocked fan.

How to use the A.O. Simth water heater error code table above

Watch out: some water heater defects represent dangerous conditions, risking fire, explosion, or carbon monoxide poisoning or scalding hazards. Work on these heaters must be by a qualifed service professional.

See the water heater manual or troubleshooting manual for your specific water heater model for expanded detail about the meaning and the corrective steps for each of these error codes.

See A.O. Smith CONDENSING WATER HEATER TROUBLESHOOTING GUIDE [PDF], (2011) A.O. Smith Water Products Company 500 Tennessee Waltz Parkway Ashland City, TN 37015 Toll Free: 1‐877‐737‐2840

Also see TAKAGI WATER HEATER MANUALS, AGE, ERROR CODES - Takagi water heaters are distributed in North America by A.O. Smith.

Also see this TB-A028-06 - A. O. SMITH - FVIR INTELLI-VENT TROUBLESHOOTING CHART that gives LED status codes for the AO Smith Intelli-Vent™ control.

Question: troubleshooting the Combustion Chamber Temperature Sensor - TCO thermal switch on an AO Smith Water Heater

(Apr 9, 2018) john said:
Hello, I have a bit of a situation on my hands and I would really appreciate some help. Our Promax Plus water heater suddenly stopped working a few days ago so we ran to lowes and purchased a universal thermocouple.

When we took out the old thermocouple I noticed that it had a TCO while the universal one did not, no big deal i thought so i installed the new universal thermocouple and the pilot fired right up, literally.

This was yesterday. Well for the rest of the day the heater stayed on, again literally, but i figured it was normal since it was a new thermocouple. Fast forward to today and the furnace was still turned on. Turned on like when someone is taking a shower or is using hot water. Now i know this isnt normal and very dangerous so we turned off the heater and turned the gas to off.

So to summarize the heater stayed on after we replaced the thermocouple with a universal one with no TCO. Could the lack of a TCO in the new thermocouple have caused this or is it something else?

Reply: TCO Temperature Cut-Off thermal reset switch on an A.O. Smith Water Heater.

Below is A.O. Smith corporation's description of their thermal cutoff sensor on the thermocouple:

COMBUSTION CHAMBER TEMPERATURE SENSOR - The C3 Technology water heaters will come equipped with a thermal cutoff (TCO) device that is integral with the thermocouple. Temperature cutoff points range from 160°C to 200°C depending on model. The TCO is an automatic reset thermal switch.

When activated it will open the thermocouple circuit and shut off the main and pilot burner gas flow. The pilot would have to be relit after the TCO has had sufficient time to cool down (sensor is below 120 degrees F).

The TCO performs two primary functions:

• In the event of flammable vapor ignition inside the combustion chamber, it senses the corresponding increase in temperature and shuts off gas flow to the main and pilot burners.

• If excessive temperatures inside the combustion chamber indicate poor combustion due to a clogged LDO screen or inadequate air for combustion, the TCO will shut off gas flow to the main and pilot burners.

John, from the above you'll see that the absence of a TCO on a thermocouple would not be likely to force a burner to stay on. I think more-likely the thermocouple you installed is defective or is not properly installed. I've found, for example, occasional operating problems when the end of the thermocouple that screws into the gas valve is not properly seated.

Watchout: The situation you describe is unsafe. I would leave the heater off pending proper repair.

Reader follow-up:

I really appreciate your response. The heater has been off since yesterday and wont be turned on again until the problem is fixed. The installation itself was actually something that I was going to double check.

Someone suggested the thermostat be replaced, is a faulty thermostat a possibility? This seems unlikely since it was working fine before.

Reply: details of the TCO on an AOS water heater

(Apr 10, 2018) (mod) said:
John

When a gas fired water heater burner won't turn OFF indeed I suspect a bad temperature sensor or thermostatic control. That's because the thermocouple has a more narrowly-defined job: confirming that there is a proper gas flame. The thermocouple is intended to shut OFF the burner IF there is no gas flame - so as to avoid continuing to pour explosive gas, un-ignited, into the building.

It's a safety device focused on proper gas ignition.

If your burner has GOT proper ignition and is burning on continuously, AND if no hot water is being taken out of the tank, it'd make sense to look for a bad thermostatic control.

What's troubling of course is that I inferred from your question that previously the heater was not turning ON and you had no hot water.

Below is a photo of AO Smith's 160 deg TCO.

Also see this AO SMITH GAS & ELECTRIC WATER HEATER SERVICE MANUAL [PDF] at inspectapedia.com/plumbing/AO-Smith-Gas-Electric-Water-Heater-Service-Manual.pdf retrieved 2018/04/10, original source: AO Smith www.hotwater.com/lit/training/320991-000.pdf

Reader Comments & Q&A

On 2020-09-15 - by (mod) -

James
SEARS KENMORE WATER HEATER AGE & MANUALS should be more accurate than a mere guess of Aug 1997 - see
https://inspectapedia.com/plumbing/Sears-Kenmore-Water-Heater-Age-Manuals.php

On 2020-09-15 by james Bique

Have a Kenmore Power Miser 6 Model 220.394100 serial# S 0897C11602 what is the year of manufacturing?

On 2020-09-01 by ted friedberg

Ao Smith Water Heater Age

what is age of my ao smith water heater Model ELJ40 S# AEB308165-Z99

On 2020-08-31 by Maureen

How old is my water heater? Thank you

Ao Smith Water Heater Age By Serial

On 2020-04-10 - by (mod) -

As your serial number format doesn't exactly match the examples we've found for de-coding AOS water heater age,
a guess is
AD6A067772
Ser# FB00A123456 decodes to F=Factory code, B=month code using A - N for January - December (the letter I is not used) and the next two digits encode the year.
- example: Ser# GB92-03123456-789 decodes to Factory ID=G, Month=B or February, Year=92 or 1992.
so AD - D = April and 06 = 2006
Let's do a sanity check: how old is the house where this heater is installed? What are the country and city? Are there any service tags or is there a manual with the heater (and what's the publication date of the manual?)
Please attach a photo of the data tag

On 2020-04-10 - by (mod) -

As your serial number format doesn't exactly match the examples we've found for de-coding AOS water heater age,
a guess is
AD6A067772
Ser# FB00A123456 decodes to F=Factory code, B=month code using A - N for January - December (the letter I is not used) and the next two digits encode the year.
- example: Ser# GB92-03123456-789 decodes to Factory ID=G, Month=B or February, Year=92 or 1992.
so AD - D = April and 06 = 2006
Let's do a sanity check: how old is the house where this heater is installed? What are the country and city? Are there any service tags or is there a manual with the heater (and what's the publication date of the manual?)
Please attach a photo of the data tag

On 2020-04-10 by Charlotte Skipper

Our water heater (electric) has serial number AD6A067772. What is the age, please?
Thanks!

On 2020-02-21 - by (mod) -

Can't say Rosemarie as we have not a shred of data, just six words of text.
But if your water heater is an AO Smith unit, take a look at the data tag on your heater, find the serial number, then compare it's format and characters with the AO Smith water heater decoding guides given above on this page.
You are also welcome to try the 'add image' button to post a photo of your heater's data tag.
Knowing the country, city, and age of the home are also useful.

On 2020-02-21 by Rosemarie Grimmell

How Old is this water heater?

On 2019-11-16 - by (mod) -

Jack,
AO Smith water heater age decoders are given on the page above.
Your format SN # F06A147109 looks closest to this decoding example given above
Ser# FB00A123456 that's explained in the article, as
Ser# FB00A123456 decodes to F=Factory code, B=month code using A - N for January - December (the letter I is not used) and the next two digits encode the year.
- example: Ser# GB92-03123456-789 decodes to Factory ID=G, Month=B or February, Year=92 or 1992.
but it's not an exact match.
1. Is this an A.O. Smith water heater?
2. if so and if it doesn't match the known codes we can guess at 2006 or you could try asking them [email protected]
3. Let's have a 'sanity check' - what are the country and city of your water heater and what is the age of the building where it's installed?
The company's more-recent water heater data tags encode the year as
YYWW123456 where YY = year and WW = week number from 1-52
Please attach a sharp photo of the data tag found on your water heater by using the add image button

On 2019-11-16 by Jack

Trying to figure out year of hot water heater. SN # F06A147109

On 2019-10-20 - by (mod) -

I don't know I would need more information to even make a guess. Perhaps you can attach a photo.

On 2019-10-20 by George

Installed by previous owner, no manual. Black plastic cover exploded onto floor under heater. What gives?

On 2019-10-20 by g

george

On 2019-07-19 by (mod) -

Anon
Let me know which manual you're looking at - one of ours? And that'll make it easier for me to research its publication date.

On 2019-07-19 by Anonymous

Need publication date for owners manuals. No date on manuals, but identified as part numbers 184165-003 and 320388-001.

On 2019-07-07 by Caryn

We own a AO smith has water heater. It flashes six times but no hot water. We unplugged it. It went through four cycles but then just shuts down. Any ideas?

On 2018-12-25 by (mod) -

EG
You can turn off the water heater when leaving for several days or longer, and will save a little money - standby losses from modern water heaters are not very great.
Conventional wisdom is that one can reduce the cost of electric hot water, if you use hot water at fairly regularly times, by having have an electrician install an automatic timer that turns the heater off for periods when it will not be in use -

see TIMERS for ELECTRIC WATER HEATERS inspectapedia.com/Energy/Hot_Water_Heater_Timers.php
Interestingly, Elk and Auberg found that timers don't save much energy, but that where hot water use occurs at regular times, turning the heater down (or maybe off) after the last daily use can save money. Here is an excerpt:
It is apparent that for no-flow standby loss reduction, the use of a clock-timer is marginal at best~ A more appropriate test sequence would be one which represents a typical household water use pattern, allowing the tank to be de-energized prior to the final hot water use during the day. Under idealized conditions, the upper limit of savings achievable with a clock-timer would be to reduce standby losses to zero for the duration of the u'off' time by completely using the last tankful of heated water.
A more realistic limit would be to use the last tankful down to about 100degF which would reduce the temperature differential to about 30 degrees over ambient the off period.
Calvin W. Ek, P.E. and Co Douglas Auburg, PeE., CEM, ELECTRIC WATER HEATER STANDBY LOSSES: COMPARISON OF CONSERVATION STRATEGIES AND THEIR ENERGY SAVINGS, Bonneville Power Administration (un-dated), retrieved 2018/12/25, original source: aceee.org/files/proceedings/1984/data/papers/SS84_Panel5_Paper_06.pdf
You can find a copy of this paper at InspectApedia.com at
inspectapedia.com/plumbing/Water-Heater-Standby-Loss-Elk.pdf
Other interesting facts about standby losses of water heaters:
Gas water heaters have higher standby losses than electric water heaters as additional heat from the water tank is lost through the exhaust flue (an automagic flue damper can reduce that loss)
Larger water heater tanks, because of their larger surface area, tend to have higher standby losses.
Tankless water heaters that do not maintain any reservoir of hot water have zero standby losses.

On 2018-12-25 by EG

I have older model AO Smith electric water heater in this apartment I moved into. Is it better to keep the power turn on or turn it on and off to conserve electricity?

On 2018-08-22 by Tony

My A.O. Smith just started leaking water . serial number 75167-1h17155 model number KGL -40-751. So 1975 water heater.

On 2018-08-01 by (mod) - decoding the AO Smith data tag for manufacturing date

JT that's how I would read it, F = June, 01 = day.

On 2018-08-01 by JT

Looking for the manufacture date of: MF01-0047213-248
If I'm correct in this.... it was made in June of 2001 ... is that correct?

On 2018-07-13 by (mod) -

KC I would decode an AO Smith water heater serial number MB00-0070742 as follows:
Factory M

Month B = February

Year 00 = 2000

On 2018-07-13 1 by KC

My AO Smith water heater serial number is MB00-0070742. Would that indicate the heater was manufactured in 2000?

On 2018-07-07 by (mod) -

Yes that's how I'd interpret it, as K = Dec and 05 the year.

On 2018-07-07 by Paula

My hot water heater has serial number K05A143732. Am I correct that the date of manufacture is November of 2005?


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Technical Reviewers & References

  • 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 [ Website: www.HonestHomeInspections.com ], LLC. can be reached at 262-424-5587 or by email to [email protected]
  • 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.
  • Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 [email protected]
  • John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-873-8534 or by Email: [email protected]

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

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  • Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
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  • Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: [email protected] The firm provides professional HOME INSPECTION SERVICES and also extensive HOME INSPECTION EDUCATION and home inspection-related PUBLICATIONS. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
    Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
    The ILLUSTRATED HOME illustrates construction details and building components, a reference for owners & inspectors.
    Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page 'Promo/Redemption' space.
    TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop Weldon & Associates
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Predicting how long your water heater will last can be difficult — depending on the model and fuel source, its lifetime could be anywhere between 8 and 20 years. Common conventional electric water heaters tend to last 10–15 years, and typically come with a standard six-year warranty.

If you don’t know the age of your current unit, it’s worth checking to see if you’re nearing time for replacement. It pays to prepare before your water heater gives up or fails, which can be inconvenient (at best) or catastrophic (at worst).

Since finding the date of installation isn’t always straightforward, we came up with the handy guide below to help you decode your water heater’s serial number.


Check for a manufacturer label on the side of your water heater — this should include the installation date.

If the label is missing, or the installation date is not listed, you can use the serial number to determine the age of your unit.

Ao Smith Water Heater Age Chart

Serial number formats vary by manufacturer, with the installationdate placed differently in each case. Check the brand name on your water heaterand then use the following guide to determine the age of your unit:

Rheem and Ruud

MMYY****

MM = Month of manufacture

YY = Year of manufacture

Example: 1209D1234 = December 2009

American and AO Smith

Ao Smith Water Heater Age

2008–present:

YYWW*******

YY = Year of manufacture

WW = Week of manufacture

Example: 16051234567 = 2016, 5th week (early February)

Pre-2008:

*MYY******

M = Month of manufacture

A = January | B = February | C = March | D = April | E = May | F = June | G = July | H = August | J = September | K = October | L = November | M = December

YY = Year of manufacture

Ao Smith Water Heater Age Serial

Example: 4D051234567 = April 2005

Bradford White

Bradford White’s serial numbers are a little less straightforward. The year of manufacture is noted by the first letter of the serial number, and the month is the second letter.

YM*******

Y = Year of manufacture

A = 1984 or 2004 | B = 1985 or 2005 | C = 1986 or 2006 | D = 1987 or 2007 | E = 1988 or 2008 | F = 1989 or 2009 | G = 1990 or 2010 | H = 1991 or 2011 | J = 1992 or 2012 | K = 1993 or 2013 | L = 1994 or 2014 | M = 1995 or 2015 | N = 1996 or 2016 | P = 1997 or 2017 | S = 1998 or 2018 | T = 1999 or 2019 | W = 2000 | X = 2001 | Y = 2002 | Z = 2003

Note: Bradford White water heaters manufactured 20 years apart will have the same letter designation

Ao Smith Water Heater Age

M = Month of manufacture

A = January | B = February | C = March | D = April | E = May | F = June | G = July | H = August | J = September | K = October | L = November | M = December

Example: KH6511396 = August 2013

Is your water heater’s brand not listed above?

If your water heater’s brand isn’t listed, check NACHI’s or The Water HeaterHub’s serial decoder to learn more.

Due for a replacement?

Ao Smith Water Heater Age Warranty Check


If it’s time for your old unit to go, consider upgrading to an electric heat pump water heater. The super-efficient heat pump technology can save a three-person household up to $300 a year on utility bills, plus heat pump water heaters come with a standard 10-year warranty. Many utilities also offer installation rebates — check yours here.