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How long does a tankless water heater last? Often twice as long as a tank. Here’s what determines lifespan and how to tell when it’s time for a new one.
Average tankless water heater lifespan and tankless water heater life expectancy figures are below.
| Water heater type | Typical lifespan |
|---|---|
| Gas tankless | 20+ years |
| Electric tankless | 20+ years |
| Gas storage tank | 8–12 years |
| Electric storage tank | 10–15 years |
| Heat pump water heater | 10–15 years |
The U.S. Department of Energy notes most tankless water heaters have a life expectancy of more than 20 years, with easily replaceable parts that can extend their life further.
Look at the rating plate on the side of the unit or inside the front cover. Many show a manufacture date. If not, the serial number usually encodes the year and month; each brand uses its own format. Contact the manufacturer with the serial number. Rinnai, Navien and Rheem can all confirm age and warranty status.
To find the age of Rinnai tankless water heater units, look for the manufacture date on the rating plate or contact Rinnai with the serial number.
| Component | Typical residential coverage |
|---|---|
| Heat exchanger | About 10–15 years |
| Parts | About 5 years |
| Labor | Often 1 year |
Coverage varies by brand, model, residential vs commercial use, and whether the unit was professionally installed and registered. Some brands extend coverage when installed by their certified pros. Rinnai, Navien and Rheem publish warranty documents on their websites. See also our warranty policy.
For example, the Navien tankless water heater warranty and Rinnai tankless water heater warranty both offer long heat exchanger coverage on residential models.
When replacing, a like-for-like tankless swap is usually much cheaper than the original conversion. See the installation cost guide.
Compare current whole-house models and their warranty terms.
The U.S. Department of Energy says most tankless water heaters have a life expectancy of more than 20 years. Many last longer with good water quality and annual descaling.
Check the rating plate on the side or inside the front cover for a manufacture date. The serial number also encodes the date; Rinnai customer support can decode it if the plate doesn’t show the date clearly.
Typically the heat exchanger for a longer period and other parts for a shorter period, with labor coverage often limited to the first year. Coverage depends on residential or commercial use, professional installation and registration.
Usually yes if the heat exchanger is sound and the repair is a sensor, fan, igniter or board. If the heat exchanger leaks or is badly scaled on an older unit out of warranty, replacement is often better value.
This guide is general information for U.S. homeowners, not professional advice. Gas, electrical and venting work must follow the manufacturer’s instructions and local codes, and in most areas requires a licensed plumber, electrician or gas fitter and a permit. Specifications and prices change; always confirm details on the product page and in the installation manual.
