Whirlpool Water Heater Age: Serial Number Decoder
Whirlpool-branded water heaters were built by American Water Heater Company (an A.O. Smith brand) and sold at Lowe's, so they use the same serial date code: the first four digits are the build date, with the first two being the year and the next two the week. That gives you an exact year, with no 20-year guesswork.
How old is my Whirlpool water heater?
The first four digits of the serial number are the build date: the first two are the year and the next two are the week. Type your serial for an instant date, or read it by eye with the steps below.
e.g. Where's my serial number?
Standard Whirlpool tank models use this code. Some specialty or non-standard units may use a different serial format.
Where to find your serial number
- Find the rating/specification label on the tank. On Whirlpool units the location varies by model — check the side and front first, then lower on the tank near the burner access.
- The serial number sits next to the model number; the first four digits are the date code (for example, 1104T403904).
- Whirlpool's own support says the serial may be on a label near the bottom of the water heater, so check there if you cannot find it higher up.
How to read a Whirlpool serial number
Rules last verified 2026-06-01Read the first four digits of the serial number. The first two are the year (20YY) and the next two are the week of that year (01 through 53). A single letter may sit in front of the digits. Whirlpool used this numeric code for its whole run, roughly 2000 to 2017.
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Find the rating plate and serial number
Look for the rating/specification label on the tank. On Whirlpool units it is often on the side or front, and sometimes lower on the tank near the burner access. The serial number sits next to the model number.
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Read the first two digits for the year
The first two digits are the year of manufacture. For example, 11 means 2011 and 01 means 2001. A single letter in front of the digits can be ignored.
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Read the next two digits for the week
The third and fourth digits are the week of the year, 01 through 53. Week 04 is late January, week 28 is mid-July, week 40 is early October. That gives you the approximate month.
Worked examples
1104T403904 11 is the year 2011; 04 is week 4, in late January. Built around January 2011.
0128104380 01 is the year 2001; 28 is week 28, in mid-July. Built around July 2001 — the same numeric code goes back to the start of the Whirlpool line.
Who actually made Whirlpool water heaters
Whirlpool Corporation did not build these water heaters. They were made by American Water Heater Company — an A.O. Smith brand based in Johnson City, Tennessee — and sold under the Whirlpool name, primarily at Lowe's, from about 2000 until Lowe's switched to the A.O. Smith brand around 2017. That is why a Whirlpool water heater uses the exact same first-four-digit date code as American and A.O. Smith. This page is for Whirlpool water heaters; Whirlpool refrigerators, washers, and other appliances use a different serial date code and are not covered here.
What your manufacture date tells you
Warranty
Whirlpool water heaters were sold in warranty tiers (commonly 6, 9, or 12 years on the tank), and the number in the model name usually matches the tank-warranty length. Coverage generally runs from the original installation date; when install proof is missing, the serial's manufacture date can serve as a fallback estimate. Because the line is discontinued, check coverage through the Whirlpool Owner Center warranty lookup with your serial number.
Check warranty by serial at Whirlpool ↗
How long they last and when to replace
A.O. Smith, which built Whirlpool water heaters, puts most of its water heaters at about 8 to 12 years and suggests replacement is worth considering after 10 years if the unit leaks or runs erratically.
Home inspectors generally treat 10 to 12 years as the typical service life for a tank water heater, and many flag units past 15 years for replacement. (Industry guidance.)
Whirlpool's range was almost entirely tank water heaters; tank units rarely run past 15 years.
Watch for these replacement warning signs:
- Age past 10 to 12 years. At or beyond typical tank service life; start planning a replacement, especially since Whirlpool parts are harder to source now.
- Pilot will not stay lit. A common Whirlpool/American complaint — often a failed thermocouple or a clogged combustion air-intake screen. See the known-issues note below.
- Rusty hot water. Discoloration from the hot tap can signal internal tank corrosion.
- Leaks at the base. Water around the base needs immediate attention and often means the tank is failing.
Why the age matters
Whirlpool recalls and your serial
Whirlpool-branded gas water heaters were part of A.O. Smith's recall of about 616,000 Ultra-Low NOx units (30, 40, and 50 gallon) over a fire hazard. These were sold primarily in California, and the recall is keyed to the same first-four-digit serial code this page decodes. The burner screen can tear and let the burner throw excess radiant heat.
- Affected models
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30, 40 & 50-gallon gas Ultra-Low NOxSold as Whirlpool / American / A.O. Smith / State / Kenmore / Reliance / U.S. Craftmaster - Affected serials
- First four serial digits 1115 through 1631 — week 15 of 2011 through week 31 of 2016 (built April 8, 2011 to August 1, 2016). CPSC recall announced November 8, 2018.
- Hazard
- A torn burner screen can cause excess radiant heat and a fire if the heater sits directly on a wood or other combustible floor.
- Remedy
- Check your model and serial at waterheaterrecall.com for a free repair kit, or call the Whirlpool / American / U.S. Craftmaster recall line at (866) 854-2793.
Two other issues affect older Whirlpool units: a 2005 recall of Robertshaw R110 gas control valves (made July 25 to August 14, 2005) covered Whirlpool among many brands, and a class-action settlement (reported 2008) covered Whirlpool Flame Lock / Flame Guard gas heaters bought roughly 2000 to 2006 over thermocouple and pilot-light failures. That settlement's claim window closed years ago — it is historical context, not a current remedy.
Read the official CPSC recall notice ↗ Recall list last checked 2026-06-01
Can't read the serial number?
If the rating plate is corroded, painted over, or missing, try these in order.
- If the rating plate is damaged, check a building permit, install sticker, or service tag for an installation date as a rough age.
- Use the Whirlpool Owner Center warranty lookup with the serial number to confirm the build date and any remaining coverage.
- Because Whirlpool water heaters share parts and dating with American, the American resources can also help date an older unit.
Model number vs serial number
The model number identifies the unit's size and warranty tier, not its build date. Only the serial number's first four digits carry the year and week. On many Whirlpool models the number in the model name matches the tank-warranty length (for example, a 12-year model), and a separate two-digit number often indicates the nominal tank capacity in gallons — confirm exact specs on the official spec sheet.
Frequently asked questions
How do I tell the age of my Whirlpool water heater?
Read the first four digits of the serial number on the rating plate. The first two are the year (for example, 11 = 2011) and the next two are the week of that year. Enter the serial in the decoder above for an instant build date.
What do the first four digits of a Whirlpool serial number mean?
The first two digits are the year of manufacture (20YY) and the next two are the week, 01 through 53. A single letter in front of the digits can be ignored. The week tells you the approximate month.
Who makes Whirlpool water heaters?
American Water Heater Company, an A.O. Smith brand in Johnson City, Tennessee, built Whirlpool water heaters and sold them under the Whirlpool name (mostly at Lowe's). Whirlpool Corporation did not manufacture them, which is why they share the A.O. Smith-family serial date code.
Does Whirlpool still make water heaters?
No. Lowe's switched from Whirlpool to the A.O. Smith brand around 2017, so Whirlpool water heaters are no longer made. The Whirlpool Owner Center still supports existing owners with warranty checks, manuals, and parts help.
Is this the same as a Whirlpool refrigerator or washer serial number?
No. This page is only for Whirlpool water heaters, which use the A.O. Smith first-four-digit year-and-week code. Whirlpool appliances like refrigerators and washers use a different serial date code and are not covered here.
Where is the serial number on a Whirlpool water heater?
On the rating/specification label on the tank, next to the model number. The location varies by model — check the side and front, and lower on the tank near the burner access if you cannot find it higher up.
My Whirlpool water heater pilot will not stay lit. Is that an age problem?
It is a very common Whirlpool/American complaint, usually a failed thermocouple or a clogged combustion air-intake screen rather than age alone. Older Flame Lock and Flame Guard models were part of a class-action settlement over this, though that claim window has long closed. Knowing the build date helps you decide between a repair and replacement.
My Whirlpool serial doesn't start with four digits. How do I read it?
Whirlpool water heaters generally use the four-digit numeric code from the start of the line, so a serial that does not begin with four digits is unusual. Use the Whirlpool Owner Center warranty lookup with your full serial, and treat any older or unusual format as an estimate.
How long do Whirlpool water heaters last?
A.O. Smith, which built Whirlpool water heaters, puts most tanks at about 8 to 12 years, with replacement worth considering after 10 years. Because the brand is discontinued, plan ahead — sourcing original parts gets harder over time.
Is my Whirlpool unit part of the Ultra-Low NOx recall?
Whirlpool-branded gas Ultra-Low NOx units with serial first-four-digits 1115 through 1631 (built April 2011 to August 2016) were recalled for a fire hazard. Check your model and serial at waterheaterrecall.com, or call (866) 854-2793.
Sources & verification
The serial and date-code rules and examples are sourced below — from manufacturer and inspector references — with recall data from the CPSC. Edge-case formats and broader context (lifespan, inspection, insurance, code) are separately sourced too. Confirm an individual unit with the official lookup.
Whirlpool water heaters use the first-four-digit year+week date code; documented examples 1104T403904 = 2011 week 4 and 0128104380 = 2001 week 28. Only numeric YYWW styles are shown — no letter-based Whirlpool format.
Official owner center for existing Whirlpool water-heater owners: warranty-status check, manuals, troubleshooting, service-provider lookup, and recall notice. No current product catalog (the brand is no longer sold new).
American Water Heater Company (Johnson City, TN) supplied Lowe's Whirlpool-branded water heaters; American's parent GSW was acquired by A.O. Smith, completed April 2006. Whirlpool Corporation did not build the heaters — it was a licensed brand on American/A.O. Smith product.
A class-action settlement (reported 2008) covered Whirlpool Flame Lock / Flame Guard gas water heaters purchased roughly 2000–2006 over thermocouple / pilot-stays-lit failures, offering a free upgraded manifold door assembly and limited thermocouple reimbursements.
~616,000 30/40/50-gallon gas Ultra-Low NOx water heaters built Apr 8 2011–Aug 1 2016 (serial first-four-digits 1115 through 1631) recalled for a burner-screen fire hazard (recall announced Nov 8 2018); sold under A.O. Smith, State, American, Kenmore, Reliance, U.S. Craftmaster, and Whirlpool. Check model+serial at waterheaterrecall.com. Recall hotline differs by brand: American/Whirlpool/U.S. Craftmaster 866-854-2793; A.O. Smith/State/Reliance/Kenmore 866-880-4661.
2005 recall of Robertshaw R110 gas control valves (made July 25 to August 14, 2005) installed on water heaters from many brands (including Bradford White and A.O. Smith-family units); broken valve screws could leak gas (explosion/fire risk).