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Ruud Water Heater Age Lookup

Ruud shares Rheem's engineering and date-code format across its full residential and commercial range. Enter your serial number to decode the exact manufacture date and age. Free with instant results.

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Ruud Water Heater

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Finding Your Ruud Serial Number

Check these four spots on your Ruud water heater

Ruud water heater serial number locations

Common Locations

1
Side panel
near the bottom
2
Front panel
access / service door
3
Behind covers
removable access panels
4
Jacket label
upper side or top of tank

What to Look For

  • White or metallic manufacturer sticker
  • Labeled "Serial No." or "S/N"
  • Typically 8–12 characters long
  • Usually near the model number

Can't find it? Try removing access panels or checking behind the temperature dial.

Ruud Serial Number Examples

Ruud
M092504723F05123456705.05-000021
Ruud decodes like Rheem (same serial as Rheem and Richmond): letter prefix + date code -- modern tanks use WWYY (2-digit week + 2-digit year), older units use MMYY (month + year). Tankless uses month.year-serial.

Don't worry if yours looks different - Ruud has multiple formats and our system can decode most variations.

About Ruud Water Heaters

Edwin Ruud, a Norwegian immigrant working in Pittsburgh, patented the automatic storage water heater in 1889 and founded Ruud Manufacturing in 1897. That invention is why a tank refills and reheats on its own instead of waiting for someone to light it, and it is the origin of the whole storage water heater category.

Ruud is now part of Rheem, and the two brands are the same equipment. A Ruud Achiever or Ultra is the wholesale channel twin of the corresponding Rheem Performance or Professional model, off the same line, with the same tank, the same gas valve, and in most cases identical warranty terms. Ruud is not an upmarket tier, it is a different label for a different distribution channel. The practical consequence is where you can buy one and who can get parts for it: a plumbing wholesaler, not a retail store.

Serials follow Rheem conventions. A letter prefix identifies plant and product, then four digits carry the month and year, with some plants using the production week instead, then the sequence, so RU1001DO4166 reads October 2001. Tankless units use a different layout, a dotted month and year, so a Ruud tankless serial will not read correctly against a tank chart.

Where to find the serial

Ruud rating plates wrap around the top of the tank near the cold inlet, very similar to Rheem (same parent company, same factories). Look for SERIAL NO. printed in black on the silver or white foil. On Ruud tankless units the label is on the side or bottom of the wall-mounted box.

What the serial actually looks like

RHLN12190155678
Week 12 of 2019, late March 2019. Ruud and Rheem use the same WWYY date code in positions 5-8 of the serial.
M271612345
Older style: M is September, 27 is the day, 1 is the year digit. Pre-2000 Ruud units used various older formats that need a lookup table to decode reliably.

Why the age is worth knowing

Ruud is Rheem's channel twin - the same units sold through a different distribution network - and most residential Ruud tanks carry 6 to 12 year tank warranties. The hybrid Ultra Series heat pump models get 10 years on the tank and 5 on the compressor. After year 10, even the premium models start showing anode rod failure if you have hard water.

Quick answers for this brand

Are Ruud and Rheem the same thing?

Both brands are owned by Rheem Manufacturing and built in the same factories using the same components and the same date code system. The differences are mostly cosmetic - paint color, badge, and which distribution channel sells them. Warranty coverage can differ slightly model to model.

How do I tell a Ruud tank from a Rheem tank by serial?

You can't - the serial format is identical. The badge on the front of the unit and the model number prefix are the only reliable way to tell them apart. The age decodes the same regardless of which brand badge is on it.

Where is Ruud sold?

Ruud is sold through HVAC wholesale distributors and contractor networks, while Rheem branded units appear at Home Depot and through plumbing wholesalers. Some markets see one brand more than the other depending on which distributor signed up first.