Every effort is undertaken to offer you correct and concise information to assist you in determining the age or manufacture date of HVAC equipment. Anytime anyone is dealing with numbers and letters in determining data, mistakes and misinterpretation are bound to happen. For this reason if you find during your research that we may have erred please contact us. In addition perhaps you have come across a brand, model or serial number format that we have not addressed. Email us information or pictures of data/nomenclature plates of the unit and we will attempt to assist you in your determinations. Email
This page was last updated: 8 October 2009
There are two styles found for Rheem
Style 1
Rheem – Late 70’s to Present Day
Serial Number format: CB5D302F099903346
(This serial number was transcribed from an actual unit during a home inspection).
Using the four digits located after the last letter in the serial number (usually an “F” or “M” located in the center or 8th digit of the serial number) CB5D302F099903346 you will find the week and year of manufacture. The first two digits are the week of manufacture and the last two digits are the year. This unit was manufactured in the 9th week of 1999.
Week of manufacture: CB5D302F099903346
Year of manufacture: CB5D302F099903346
Style 2
Rheem – 1955 to Early 70’s
Serial Number format: 123451872
(This serial number is fictitious).
Using the last four digits of the serial number, 123451872 you will find the week and year of manufacture. The first two digits are the week of manufacture and the last two digits are the year. This unit was manufactured in the 18th week of 1972.
Week of manufacture: 123451872
Year of manufacture: 123451872