Rheem and Ruud water heater age by serial number

Reviewed 2026-10-156 primary sourcesSee sources

Rheem’s technical bulletin describes two serial layouts. Older serials start with the month and year. From April 2012 the factories moved, one by one, to a layout that starts with a plant letter, then the week and year.

Covers: Rheem, Ruud and Richmond tank, tankless and heat pump water heaters.

Where to find the serial number

• The serial number is on the product rating label. Labels used since 2012 also print the date of manufacture on their third line.^[1]

Date formats Rheem documents

Month + year + plant linebefore the 2012 changeover

Rheem gives a two-digit year without the century. We read it within 1980–2014, which is our assumption.^[1]

Plant + week + yearfrom April 2012

A letter after the number marks a converted unit. Rheem’s newer rating labels also print the manufacture date on the third line.^[1]

What Rheem says

• The Mexicali plant started the new layout on April 2, 2012 and Nuevo Laredo on June 4; other plants switched as they moved to a new system. Rheem doesn’t give their dates.^[1]
• Rheem’s consumer web page still shows only the older month-and-year example; the technical bulletin adds the 2012 layout.^[2]

Worked examples

• M141209135: Mexicali plant, week 14 of 2012 (Rheem’s example).^[1]
• Q231299996: Nuevo Laredo plant, week 23 of 2012 (Rheem’s example).^[1]
• 0912D01234: Older layout: September 2012, plant line D (Rheem’s example).^[1]

What the serial can’t tell you

• Warranty is based on the manufacture date and the warranty code in the model number, not on the serial alone. Rheem asks owners to call its warranty line to confirm.^[1]
• The newer layout gives a week, not a month or day, and Rheem doesn’t define how weeks map to dates.^[1]
• When you ask Rheem for service it wants the model, the serial and the date of original installation; the serial doesn’t carry the installation date.^[5]
• The year the Nuevo Laredo plant changed layouts (Rheem prints only “June 4”), and the dates for its other plants.
• Rheem serial formats before the month-and-year layout.

Recalls on record

The U.S. Consumer Product Safety Commission lists these recalls naming Rheem equipment. Check the recall notice itself for the exact models and serial ranges.

• Rheem Recalls to Repair Water Heaters Due to Fire and Burn Hazards; Sold Exclusively at Home Depot (2016-05-26, recall 16177)^[6]

Ask Rheem

• Ruud water heater age calculator: Ruud’s own tool takes a serial number and returns the manufacture date.^[4]
• Where Rheem puts the serial number: Rheem’s page on finding the serial on tank, tankless and hybrid models.^[3]