How long do tankless water heaters last?
Most tankless water heaters last 15 to 25 years. The Department of Energy says tankless water heaters last about 20 years or more, and parts can be replaced.
Tankless units last longer than tanks but need descaling, especially with hard water. Skipping it is the most common reason they fail early.
Typical lifespan: 15 to 25 years
The Department of Energy says tankless water heaters last about 20 years or more, and parts can be replaced.
Tankless water heater maintenance checklist by season
Spring
Check the exhaust vent and the intake for blockage. Look at the isolation valves and connections for mineral buildup or drips.
Summer
Clean the inlet water filter screen as the manual describes. Note any error codes and how long hot water takes to arrive.
Fall
Descale the heat exchanger. Makers commonly advise this about once a year, and more often with hard water. A plumber can do it, or you can with a descaling kit if your manual allows it.
Winter
In freezing weather, check that any freeze protection is working and that the vent termination is clear of snow. Keep power on to the unit, since most protection depends on it.
Signs your tankless water heater needs replacing
- Error codes for flow, ignition or heat exchanger that return after descaling.
- The water runs lukewarm or fluctuates, even with the correct flow.
- Visible scale in the filter or on the isolation valves.
- Leaks from the heat exchanger.
- The unit is past roughly 20 years or parts are no longer made.
Typical tankless water heater warranty
Heat exchanger warranties are commonly 10 to 15 years on the part, with shorter coverage of one to five years on other parts, and labor is often excluded after the first year. Terms vary, and professional installation is often a condition.
An appliance warranty tracker keeps your tankless water heater's coverage dates and receipt in one place.
What to keep for a tankless water heater
- The installation invoice, which often must show a licensed installer
- Model and serial number from the label on the unit
- The descaling log with dates
- The warranty card
Common questions
How long do tankless water heaters last?
Most tankless water heaters last 15 to 25 years. The Department of Energy says tankless water heaters last about 20 years or more, and parts can be replaced.
How often should a tankless water heater be flushed?
Many manufacturers suggest about once a year, more often if your water is hard. Check your manual.
Is a tankless water heater worth it?
It can save energy because it heats only when you use hot water, and the Department of Energy reports it can be more efficient than a tank. Compare the higher upfront cost and your household use before deciding.
How do I maintain a tankless water heater?
Follow your manual first. Each season: spring, check the exhaust vent and the intake for blockage. Look at the isolation valves and connections for mineral buildup or drips. Fall, descale the heat exchanger. Makers commonly advise this about once a year, and more often with hard water. A plumber can do it, or you can with a descaling kit if your manual allows it.