Find Your WeatherKing Water Heater's Age
The fastest way to date a WeatherKing water heater is the serial number on its rating plate. WeatherKing is a Rheem Manufacturing brand — the same company behind Rheem, Ruud, and Richmond — and although the label is best known for furnaces and air conditioners, WeatherKing-branded water heaters roll out of Rheem factories with Rheem-style serial numbers. Enter your serial number in the free decoder above, or read on to decode it by hand.
Where to Find the Serial Number
Look for the rating plate (also called the data plate) — a silver or white sticker on the side of the tank, usually in the upper half on gas and electric tank models. It shows the model number, serial number, capacity, and input rating, and on many newer units it prints the manufacture date in plain text next to the serial.
How the WeatherKing Serial Format Works
Modern format (month + year). Ignore the letter prefix — WeatherKing serials may start with W, R, RN, RH, and similar factory prefixes, just like Rheem. The first four digits after the prefix are the date: two digits for the month, then two for the year.
Worked example — W 0321 B10488:
- Prefix:
W(ignore) 03= March (month)21= 2021 (year)- Result: manufactured March 2021
Older format (week + year). Some older serials encode the week of the year instead of the month. The first two digits are the week (01–52), the next two are the year. For example, W291013412 decodes to week 29 of 2010 — mid-July 2010.
If your serial doesn't fit either pattern, check the rating plate for a printed manufacture date, which overrides the serial.
Why the Age of Your WeatherKing Water Heater Matters
- Lifespan. Tank-style water heaters typically last 8–12 years. Past that window, the risk of tank corrosion and leaks climbs sharply — and a failed tank can release dozens of gallons of water into your home.
- Warranty. Rheem-family tank warranties commonly run 6, 9, or 12 years from the manufacture date (not the install date), depending on the model. The serial number tells you whether you're still covered before you pay for a repair.
- Replacement planning. Knowing the exact age lets you replace on your schedule — comparing quotes and choosing a model — instead of making an emergency decision after a failure.
- Buying or selling a home. Inspectors routinely report water heater age, and a unit near the end of its life often becomes a negotiation point.
Sources
Brand ownership and serial format details verified against the Building Intelligence Center's WeatherKing age guide (Rheem Manufacturing brand list and Rheem-style serial examples), Rheem's official serial number guide, the InterNACHI water heater dating chart, and InspectApedia's Rheem water heater age decoder.