Ruud serial number lookup: age of a furnace, AC or heat pump
The serial number is on a tag on the back of the outdoor unit or inside the front cover of the indoor unit. Ruud equipment is built by Rheem: the two digits after the last letter in the serial are the week and the next two are the year.
Decode a Ruud serial number
How to read a Ruud serial number
Plant letter, then week and year
Find the last letter in the serial. The two digits after it are the week and the next two are the year.
Shape: ends with a letter followed by nine digits. Older serials have a prefix of letters and digits in front.
7351M280616735 reads as week 28 of 2006 (around July).
Rheem does not publish its week calendar, so the month shown for a week is approximate. Rheem water heaters use a different code.
Where to find the serial number
A split system has two tags: one on the back of the outdoor unit and one on the inside of the front cover of the indoor unit.
A packaged unit has a single tag on an outside corner.
If the serial number does not decode
- Ruud heating and cooling equipment is built by Rheem and differs from Rheem equipment only in its label. Ruud model numbers begin with U where Rheem model numbers begin with R.
- Many Ruud plates also print the month and year of manufacture at the upper right, as in “MFD. 07/04”. Use it to check the decoded week.
- Ruud water heaters use a different code. Choose “water heater” for those.
- The manufacturer can confirm the date from the serial: Ruud registration, warranty or serial lookup.
What the age tells you
| Equipment | Typical service life |
|---|---|
| Furnace | 15 to 22 years |
| Central air conditioner | 10 to 21 years |
| Heat pump | 15 to 16 years |
What size is it?
The model number on the same rating plate gives the size: the tonnage of an air conditioner or heat pump, or the heating input of a furnace. Rheem model number tonnage shows where the digits sit and reads them for you.
About Ruud
Ruud was founded in Pittsburgh in 1897 and was bought by Rheem in 1960. Ruud water heaters, furnaces and air conditioners are built by Rheem and carry Rheem serial numbers.
Brands that share this serial system: Rheem.
Questions and answers
Which characters in a Ruud serial number show the date?
Find the last letter in the serial. The two digits after it are the week and the next two are the year. This applies to units built since the early 1990s.
Who makes Ruud heating and cooling equipment?
Ruud heating and cooling equipment is built by Rheem and differs from Rheem equipment only in its label. Ruud model numbers begin with U where Rheem model numbers begin with R.
Sources
- CPSC recall: Rheem electric furnaces and air handlers sold 1992 to 1995, date code after the letter in the serial (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/1999/cpsc-rheem-manufacturing-announce-recall-to-repair-electric-furnaces-and-air-handlers
- CPSC recall: Rheem and Ruud oil furnaces sold 2006 to 2008, date code after the letter M in the serial (US Consumer Product Safety Commission): https://www.cpsc.gov/Recalls/2009/rheem-recalls-to-repair-oil-fired-furnaces-due-to-fire-hazard
- Building Intelligence Center: Rheem HVAC age (independent reference): https://www.building-center.org/rheem-hvac-age/
- Rheem: how old is my equipment (sample serials) (manufacturer): https://www.rheem.com/how-old-is-my-equipment/
- Building Intelligence Center: Ruud HVAC age (independent reference): https://www.building-center.org/ruud-hvac-age/
Formats last checked against these sources on October 5, 2026. Found a serial that does not fit? Send a correction. How formats are verified: method and sources.