How Often Should You Descale a Tankless Water Heater in a Hard Water Area?

How often a tankless water heater should be descaled depends on the manufacturer, water quality and how heavily the system is used. In Arlington and Fort Worth, where water typically ranges from moderately hard to hard, many manufacturers recommend descaling about once a year, although a household’s water usage or the use of a water softener may justify more or less frequent descaling. 

Why Hard Water Is a Problem for Tankless Water Heaters

Tankless water heaters do not store gallons of water in a tank, but that does not mean they are immune to mineral buildup. Instead of collecting in the tank, calcium and other minerals are gradually deposited in a tankless water heater’s heat exchanger and internal water passages.

That buildup can reduce the efficiency of heat transfer and gradually restrict water flow.

What Happens If You Never Descale a Tankless Water Heater?

As with traditional tank water heaters, tankless water heaters may continue operating fine for years without any maintenance or descaling. The decrease in performance and efficiency is gradual, but without any intervention, the buildup will eventually result in:  

• Reduced heat-transfer efficiency
• Restricted water flow through the unit
• Less consistent water temperature
• Error codes or shutdowns
• Accelerated wear on the heat exchanger and other components

What Does Tankless Water Heater Descaling Involve?

Descaling removes mineral deposits from the internal waterways and heat exchanger.

The process generally involves:

1. Disconnecting the water heater from the home's plumbing
2. Connecting hoses to the service valves
3. Using a small pump to circulate vinegar or an approved descaling solution through the unit
4. Flushing the system with clean water
5. Reconnecting it to the home’s plumbing

Unlike a traditional tank water heater, which many homeowners can often flush themselves by connecting a garden hose to the tank’s drain valve and letting it drain outside, tankless water heaters typically benefit from professional descaling by plumbers.

Does a Water Softener Eliminate the Need for Descaling?

Water softeners or other whole-home scale-control systems can often reduce the amount of mineral scale that forms inside a tankless water heater, but they do not necessarily eliminate maintenance altogether.

The appropriate maintenance schedule still depends on the water heater, water quality and manufacturer recommendations.

How Can You Tell Scale Is Affecting Your Tankless Water Heater?

Because mineral buildup is gradual, most homeowners will not experience a sudden change in hot water performance. As scale increases, you may begin to notice:

• Hot water that does not stay at a consistent temperature
• Reduced hot-water flow
• Longer waits for water to reach the expected temperature
• Recurring error codes
• More frequent shutdowns
• A gradual decline in performance compared with when the unit was newer

Those symptoms can have other causes, so they do not automatically mean the water heater needs descaling. If performance has changed, a plumber can inspect the system and determine whether scale or another problem is responsible.

Call Tom's Mechanical for Tankless Water Heater Service in Arlington and Fort Worth

Regular tankless water heater maintenance can help support efficient operation, consistent performance and a longer service life. Call Tom's Mechanical at (817) 277-4493 to schedule tankless water heater descaling or service.