Homeowner Resources

Find the rating plate (the label on the side of the tank or tankless cabinet) and look for the serial number. Most brands hide the manufacture date in the first few characters, and some newer labels print a manufacture date outright. Pick your brand above, type in the serial number, and the calculator shows the month and year it was made and how old it is today.

On a tank water heater, the rating plate is usually on the side of the tank in the upper half; on gas models it is often just above the gas control. On a tankless unit, check the side or bottom of the cabinet. The serial number sits next to the model number. Don't use the yellow EnergyGuide sticker or a service tag.

Rheem puts the typical life of a tank water heater at about 8 to 12 years, and notes that hard water, heavy use and skipped maintenance wear a heater out faster. The U.S. Department of Energy says tankless water heaters can last more than 20 years, compared with 10 to 15 years for storage tanks. ENERGY STAR suggests considering a replacement once a tank is more than 10 years old.

It mostly comes down to age and what's wrong. On a tank heater under about 6 years old, most problems are parts made to be replaced (like a thermostat, heating element or anode rod), so a repair usually makes sense; check your warranty first. From about 6 to 10 years, compare the repair quote with the price of a new heater: if the repair is more than about half the cost, replacing is usually the better investment. At 10 years or more, replacement is often the smarter move. A leak from the tank itself can't be patched at any age.

Not always. A heater can sit in a warehouse or on a shelf before it is installed, so the install date is usually a bit later. Each manufacturer sets its own warranty rules; many start the warranty at installation when you have proof and use the manufacture date when you don't, so keep your receipt.

Bradford White's year letters repeat every 20 years and GE's repeat every 12. The calculator uses clues in the serial (like the length of Bradford White's production number) to narrow it down. If two dates are still possible, look at the label: the ANSI/CSA standard year printed there is usually a few years older than the heater, never newer, and a UEF rating means mid-2017 or later.

Not necessarily today, but it's smart to plan ahead. ENERGY STAR suggests considering replacement after 10 years so you aren't making a rushed decision after a failure. Have a licensed pro check it for leaks, rust and sediment and walk you through your options.

Double-check look-alike characters (0 and O, 1 and I, 5 and S, 8 and B) and make sure you copied the serial number, not the model number. Look for a printed manufacture date on the label. If it still won't decode, contact the manufacturer with the model and serial number, or ask your plumber.

Most do. Navien, Rinnai, Noritz and newer Takagi serials include a date code, and the calculator decodes them. Older Takagi units used plain sequential numbers, so check the label or contact Takagi.