Reliance Water Heater Age
Reliance water heaters are made by A. O. Smith and use its date code. On newer tanks the first four digits are the year and the week. Enter the serial below to decode it.
Part of the water heater age lookup
Serial number age lookup
Where to find the Reliance serial number
The label is on the side of the tank: above the gas control on gas models, between the element covers on electric ones. Reliance model numbers usually begin with a digit for the warranty term, then the capacity and fuel, for example a model starting 6 40 is a 6-year, 40-gallon tank. The serial is the separate line beneath it.
How the Reliance date code works
Reliance follows A. O. Smith’s two eras:
- About 2008 onward: first two digits = year, next two = week.
1647A123456is week 47 of 2016 (late November). - Before 2008: the second character is a month letter (A = January … M = December, no I) and the next two digits are the year.
JF05123456is June 2005.
- Year
- Week
- Not part of the date
- Month
- Year
- Not part of the date
Worked examples
| Serial | Built | Format |
|---|---|---|
| 1647A123456 | November 2016 (week 47) | Year (2 digits) + week (2 digits) (2008–present) |
| 0915A654321 | April 2009 (week 15) | Year (2 digits) + week (2 digits) (2008–present) |
| 2108B112233 | February 2021 (week 8) | Year (2 digits) + week (2 digits) (2008–present) |
| JF05123456 | June 2005 | Month letter + year (2 digits) in characters 2–4 (before 2008) |
Example serials are made up to show the format; they don't belong to real units.
Reliance vs Reliance Home Comfort
This trips up a lot of people in Canada and the northern US. Reliance is a water heater brand made by A. O. Smith. Reliance Home Comfort is a separate Canadian home-services company that rents water heaters and HVAC equipment. A rental tank might carry the rental company’s sticker but be built by A. O. Smith, Rheem, Bradford White or GSW. Always decode using the manufacturer’s brand printed on the rating label, not a service sticker.
If you rent your water heater, the age matters differently. Under most rental agreements the provider is responsible for repairs and replacement, so an old rented tank is usually the provider’s problem. Check your agreement before you pay for anything.
How long Reliance water heaters last
| Type | Typical life |
|---|---|
| Gas tank | 8–12 years |
| Electric tank | 10–15 years |
Reliance is positioned as a value brand, and the tanks are mostly standard-warranty models. In hard water, a magnesium anode can be used up within a few years; checking it around year four is cheap insurance.
Common Reliance issues
- Pilot outages on older gas models: usually a thermocouple, or on newer flammable-vapor-resistant models a tripped sensor that needs attention.
- Lukewarm water on electric models: often a failed upper element or thermostat. Both are inexpensive to replace.
- Rumbling: sediment. Flushing helps if done before it hardens.
What to do with your result
Under 6 years: repair, and check whether the tank is still under warranty.
6 to 10 years: service it and budget for a replacement.
Over 10 years: replace on your own schedule, sooner if the heater is in a finished space. For a like-for-like swap, any A. O. Smith-family tank of the same size and venting type is a straightforward replacement.
Frequently asked questions
How do I read a Reliance water heater serial number?
On tanks built since about 2008, the first two digits are the year and the next two are the week, so 1647… is week 47 of 2016, which is late November. Older tanks have a month letter in the second position followed by a two-digit year.
Who makes Reliance water heaters?
A. O. Smith. Reliance is one of its brands, so the tanks share A. O. Smith's engineering, parts and serial code.
Is Reliance the same as Reliance Home Comfort?
No. Reliance Home Comfort is a Canadian company that rents and services water heaters. The tanks it installs can be from various manufacturers, so read the brand on the tank's own label before decoding.
How long do Reliance water heaters last?
About 8 to 12 years for a standard tank, longer with regular flushing and an anode replacement.
Sources and accuracy
The A. O. Smith / State / Reliance decoder is built from these references and cross-checked between them. Facts are restated in our own words; any mistakes are ours.
Status: being verified against real data plates. Rules last reviewed 2026-10-18; page updated 2026-10-30. Not affiliated with A. O. Smith / State / Reliance. Report a wrong result.
Part of the water heater age lookup
This page covers one brand. For all water heater brands, go to the water heater age lookup.