Tankless Water Heater Descaling: Why It Matters and How Often You Should Do It
- Mar 14
- 2 min read
Tankless water heaters are known for their efficiency and endless hot water, but they still require regular maintenance. One of the most important services for any tankless system is descaling, sometimes called flushing. If this maintenance is skipped, mineral buildup can slowly reduce performance and shorten the life of the unit.
What Is Tankless Water Heater Descaling?
Descaling is the process of circulating a cleaning solution through the heat exchanger inside the unit. This removes mineral deposits, mostly calcium and lime, that naturally accumulate from hard water. Even in areas with moderate water hardness, these minerals gradually coat the internal surfaces of the heat exchanger.
When buildup increases, the system has to work harder to heat water, which reduces efficiency and can eventually cause errors or shutdowns.
Why Descaling Is Important
Mineral scale creates several problems inside tankless units.
Reduced efficiency is one of the first signs. The heat exchanger cannot transfer heat as effectively, so the system burns more gas or uses more electricity to produce the same amount of hot water.
Flow restrictions can also occur. Heavy scaling can reduce the internal diameter of passages in the heat exchanger, which limits water flow and can cause inconsistent hot water.
Overheating is another risk. When scale builds up on heat transfer surfaces, hot spots can develop. Over time this can damage the heat exchanger, which is one of the most expensive parts of the unit.
Regular descaling helps prevent these issues and keeps the system operating the way it was designed.
How Often Should a Tankless Water Heater Be Flushed?
Most manufacturers recommend flushing the unit once per year. Homes with harder water may benefit from more frequent service.
If your home has any of the following conditions, annual descaling is especially important:
High mineral content in the water
A recirculation system
Heavy hot water usage
Older tankless units
Regular maintenance is also often required to maintain the manufacturer warranty.
Signs Your Tankless Water Heater May Need Descaling
A few common symptoms can indicate scale buildup.
Hot water runs out faster than usual
Water temperature fluctuates
Error codes related to flow or overheating appear
Reduced water pressure through hot fixtures
Sometimes there are no obvious symptoms at all, which is why preventative maintenance is recommended.
What Happens During a Tankless Flush Service
During a professional descaling service, the technician will isolate the water heater using the service valves, circulate a cleaning solution through the unit to dissolve mineral deposits, and clean any inlet water filters.
The system is then flushed with clean water and returned to normal operation. The service typically takes about an hour.
Protecting Your Tankless Investment
Tankless water heaters are designed to last a long time, often 15 to 20 years or more, but only if they are properly maintained. Routine descaling is one of the simplest and most effective ways to protect the heat exchanger and keep the system running efficiently.
If your tankless water heater has not been serviced recently, scheduling a flush is a good step toward preventing costly repairs down the road.
If you have questions about tankless maintenance or would like to schedule a descaling service, feel free to reach out. We are always happy to help homeowners keep their hot water systems running smoothly.
