How Often Should You Flush a Tankless Water Heater in Middle Tennessee?

“How often should I flush my tankless heater?”

This is one of the first questions homeowners ask me — and the internet gives about 30 different answers.

So here’s the actual, Middle Tennessee–specific answer based on Rinnai recommendations and real-world results from homes I service every week.

The True Maintenance Schedule for Middle Tennessee Homes

• Once a year is ideal for most homeowners

This keeps scale low, preserves heat efficiency, and prevents burner strain.

• High-use homes may need flushing every 9 months

Especially homes with:

• Large families

• High hot water demand

• Recirculation pumps

• Low-use, lightly occupied homes can go 12–18 months

This applies to lake homes, empty nesters, or Airbnb properties with intermittent use.

Why Middle Tennessee Needs Annual Service

Our water quality isn’t the worst — but it does contain enough minerals to create scale inside the heat exchanger over time.

You’ll start noticing signs like:

• Temperature fluctuations

• Lower flow on hot water

• Noisy operation

• Delayed heating

• Error codes tied to flow or combustion

Once these appear, scale buildup is almost always the root cause.

Why Waiting Too Long Causes Bigger Issues

Minor scale buildup is easy to remove.

Heavy buildup? Not so much.

If a system goes 3–6 years without a flush, it can lead to:

• Overheating

• Premature heat exchanger failure

• Sensor malfunction

• Poor ignition/combustion

• Reduced lifespan overall

Maintenance is cheaper than repair — and tankless repairs can get expensive fast.

The Bottom Line

If you’re a homeowner in Middle Tennessee, the simplest rule is:

Flush your tankless system once a year for best performance and peace of mind.

It’s one of the few services where you immediately notice the difference.