How old is my Ruud?
Type your Ruud serial number below to get the month and year it was built. 3 documented Ruud serial formats, covering 1980 to today.
Ruud is Rheem's second brand, built alongside Rheem with the same serial formats.
The serial number is on the metal rating plate. On a furnace it is usually inside the front door on the side wall; on an outdoor AC or heat pump it is on the back or side of the cabinet, near the refrigerant lines.
Type the Ruud serial exactly as printed. Spaces, dashes and lowercase are all fine.
Ruud serial number formats
Factory letter plus WWYY
1990 to present
Find the single factory letter (F, M, G, W or N) in the middle of the serial. The two digits right after it are the week and the next two are the year.
7351M280616735 reads as week 28 of 2006
Source: Building Intelligence Center · checked 2026-08-25
W-prefix
1990 to present
On W-prefixed serials, characters 2-3 are the week and characters 4-5 are the year.
W291013412 reads as week 29 of 2010
Source: Building Intelligence Center · checked 2026-08-25
MMYY water-heater style
1980 to 2010
The water-heater format, also used on some older Rheem HVAC units: digits 1-2 are the month and digits 3-4 the year.
0804B10488 reads as August 2004
Source: Building Intelligence Center · checked 2026-08-25
Where to find the serial on a Ruud
- Gas furnace: open the front door. The rating plate is on the inside side wall, usually near the top.
- Outdoor AC or heat pump: a metal or foil plate on the back or side of the cabinet, near where the copper lines enter.
- Mini-split: on the side of the outdoor unit, and on the indoor head behind the front flap or on its right side.
- Photograph the plate rather than copying it by hand. Misreading 0 for O, 1 for I or 5 for S is the most common reason a lookup fails.
Same serial format
These brands come off the same lines and decode identically:
Is your Ruud showing an error code?
Age tells you where the unit sits in its life. The fault code tells you what is wrong right now. We have 40 Ruud codes, each quoted from the manufacturer's own manual.
HVAC Code Lookup publishes these decoding rules from public industry references, not from Ruud. If the rating plate prints an explicit manufacture date, trust the plate over any decoder.