What Does Flushing a Tankless Water Heater Do?

Flushing a tankless water heater is a crucial maintenance task that helps maintain the unit’s efficiency and longevity. Unlike traditional tank water heaters, tankless models do not store hot water. Instead, they heat water on demand, providing an endless supply of hot water.

However, tankless water heaters are still susceptible to issues like mineral buildup, particularly in areas with hard water. Flushing the unit helps address these issues and ensures optimal performance.

1. Removing Mineral Buildup

One of the primary reasons for flushing a tankless water heater is to remove mineral buildup, particularly calcium and magnesium deposits. These minerals can accumulate on the heating elements and other internal components over time, especially in areas with hard water.

This buildup, often referred to as scale, can reduce the efficiency of the heat exchanger and cause the unit to work harder to heat the water. Flushing the system with a descaling solution helps dissolve these deposits, restoring the heater’s efficiency.

2. Maintaining Energy Efficiency

As mineral deposits accumulate, they act as an insulating barrier between the water and the heating elements. This makes it more challenging for the heater to transfer heat to the water, resulting in longer heating times and increased energy consumption.

Regularly flushing the tankless water heater removes these deposits, allowing the unit to heat water more efficiently and use less energy, which can reduce utility bills.

3. Extending the Lifespan of the Heater

Scale buildup not only reduces efficiency but can also cause long-term damage to the water heater’s internal components. Over time, the accumulation of minerals can corrode parts of the system, leading to leaks and other malfunctions.

By flushing the system regularly, homeowners can prevent these issues and extend the lifespan of their tankless water heater, delaying the need for costly repairs or replacements.

4. Improving Water Quality

Mineral buildup can also affect the quality of the water produced by the heater. As scale accumulates, it can break off and flow through the water lines, potentially leading to discolored water or an unpleasant taste. Flushing the heater removes these deposits, helping to ensure that the water remains clean and free from impurities.

5. Preventing System Shutdowns

In some cases, a tankless water heater may shut down or operate inefficiently if scale buildup becomes severe. Many modern tankless water heaters have sensors that detect issues like overheating, which can occur if scale prevents proper heat transfer.

Regular maintenance, including flushing the unit, helps prevent these shutdowns and keeps the system running smoothly.

How Often Should You Flush a Tankless Water Heater?

The frequency of flushing a tankless water heater depends on several factors, including water hardness and usage patterns.

Generally, it’s recommended to flush the system at least once a year. In areas with hard water, more frequent flushing may be necessary, perhaps every six months, to prevent excessive scale buildup.

Steps to Flush a Tankless Water Heater

1. Turn off the Power: Ensure the unit is powered down and the water supply is turned off.
2. Disconnect the Water Supply: Attach hoses to the service ports for flushing.
3. Run the Descaling Solution: Use a pump to circulate a descaling solution through the heater for about 45 minutes to an hour.
4. Rinse the System: After descaling, flush the system with clean water to remove any remaining solution and loosened minerals.
5. Reconnect and Restart: Reconnect the water supply and restore power to the unit.

Flushing a tankless water heater is an essential maintenance task that helps remove mineral buildup, maintain energy efficiency, extend the lifespan of the unit, improve water quality, and prevent system shutdowns. Regular flushing, at least once a year, is recommended to ensure the heater operates efficiently and reliably. By taking these steps, homeowners can enjoy consistent hot water supply while minimizing energy costs and avoiding potential damage to their tankless water heater. If you’re unsure about how to perform this maintenance task, consider consulting a professional plumber to ensure it’s done correctly and safely.