Water heaters

How old is my Reliance water heater?

Reliance water heaters carry the build date inside the serial number. We know 3 serial formats for this brand; the decoder tries each one and shows every reading that fits.

How to read a Reliance serial number

Year and week (about 2008 to today)

The first two digits are the year and the next two are the week of that year. An S in front is a factory code and is ignored.

1211A018632 reads as week 11 of 2012.

Two sources agree Building Intelligence Center, Energy Trust of Oregon serial charts, InterNACHI inspector forum

Month letter, then the year (older, through about 2008)

The first letter is the month (A is January, M is December, I is skipped). The two digits after it are the year.

D03304410 reads as April 2003.

Two sources say 1990s Reliance tanks used fiscal-year month letters (A for October), so on those the month could be about three months off and October to December units a year later. The 2000s units use calendar months.

Two sources agree InterNACHI water heater dating chart, Energy Trust of Oregon serial charts, Inspector's Journal decoder, Fast Water Heater Co.

Factory letter, month letter, then the year (older, ended July 2004)

The first letter is the factory. The second letter is the month. The two digits after it are the year.

AJ03123456 reads as September 2003.

Two sources agree Building Intelligence Center, Inspector's Journal decoder

Where to find the serial number

Water heater: the rating label on the side of the tank, near the EnergyGuide sticker. On a tankless unit it is on the side or bottom of the cabinet.
Use the line marked Serial No. or S/N, not the model number. If the plate prints a manufacture date, use that.

How long should it last?

Typical life of a tank water heater: 8 to 12 years

A standard tank water heater usually lasts 8 to 12 years. Some make it to 15 with soft water and a replaced anode rod; some fail at 7.

How long does a tank water heater last? · Should I replace my water heater? · DC Dept. of Energy & Environment, InterNACHI

Should I replace it?

Should I replace my water heater?

Other brands in this group

A.O. Smith · American Water Heater · U.S. Craftmaster · Bradford White · State · Kenmore · Whirlpool · Rheem · Ruud · Richmond · GE · Marathon · Rinnai · Navien · Noritz · Takagi · Bosch (tankless water heater) · Lochinvar · GSW / John Wood · Paloma · HTP / Westinghouse / American Standard (water heaters) · Giant · EcoSmart / Eemax · Stiebel Eltron

Parts that help it last

Anode rod The sacrificial rod that rusts instead of the tank. Checking it every few years is the cheapest way to add life.
Flush kit A hose and fittings for draining sediment from the bottom of the tank once a year.
Expansion tank Soaks up pressure swings in a closed plumbing system. Ask a plumber whether yours needs one.
Leak alarm A small alarm that goes on the floor beside the heater and warns you before a slow leak becomes a flood.

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