Life Expectancy for a Tankless Water Heater

Life Expectancy for a Tankless Water Heater

Learn how to properly care for your tankless water heating system

By Kathryn Keep

Tankless Water Heater
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Tankless water heaters, also called demand or instantaneous water heaters, offer an alternative to the traditional storage variety by heating water as needed rather than keeping a whole tank of water hot. This saves space as well as energy. In general, tankless water heaters last longer than storage water heaters, but there are many factors to consider when determining the life expectancy for a tankless water heater.

Time Frame

The average storage water heater can be expected to last 10 to 15 years. In contrast, a tankless water heater should last more than 20 years. This lifespan can be extended by replacing the heat exchanger, which is the main part of the tankless water heater, rather than replacing the whole unit. This is not an option when a traditional water heater's tank fails.


A tankless water heater can use either a gas or electric heating element, with gas providing the most hot water at any given time due to a higher flow rate. The typical tankless water heater can provide about two to five gallons of water every minute. This may seem like a lot, but if you are running a dishwasher and a washing machine or multiple showers at the same time, a tankless water heater won't be able to keep up.


Regular maintenance is essential to ensure your tankless water heater reaches its maximum life expectancy. A service technician or plumber can clean your tankless water heater with a special flush kit. If your tankless water heater becomes clogged, it will automatically shut off and require a reset to prevent permanent damage. It is often recommended to flush your water heater annually. However, some models are self-flushing, eliminating the need for regular maintenance.


The biggest consideration in the life expectancy for a tankless water heater is the water going through it. You may need to treat your water if it is either too hard or too acidic. Hard water will cause scale or minerals to build up, which will void your warranty. Acidic water will cause corrosion.

Further Insight

Proper installation is also important to ensuring your tankless water reaches its maximum life expectancy. Improper venting of a gas tankless water heater is also a serious safety hazard. Some tankless water heaters can be installed outdoors, but even a unit with freeze protection can freeze if the power goes out. Damage due to freezing voids your warranty as well.

About the Author

Kathryn Keep is a regular contributor to DexKnows. She is an eco-consultant, with expertise in environmental issues, home decorating, green building, and general sustainable living.

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