How to Descale a Tankless Water Heater

A tankless water heater is an energy-efficient option for providing hot water on demand. However, like any appliance that heats water, tankless units can accumulate mineral deposits over time, especially in areas with hard water. These deposits, mainly composed of calcium and magnesium, can reduce the efficiency of your heater and even cause damage. Descaling is an essential part of annual tankless water heater maintenance that helps prevent these issues. 

What Does It Mean to Descale a Tankless Water Heater?

Descaling a tankless water heater involves removing mineral buildup that forms inside the unit yearly or every six months if you have hard water. This buildup, often called limescale, occurs when hard water passes through the heater and leaves behind mineral deposits. These deposits can reduce water flow, affect heating efficiency, and increase energy consumption. Descaling helps flush out the accumulated minerals, ensuring that your heater runs efficiently and lasts longer.

Why Do Tankless Water Heaters Need to Be Descaled?

There are several reasons why regular descaling is important for tankless water heaters:

• Maintaining Efficiency: Mineral deposits form on the heating elements and other internal components, forcing the heater to work harder to reach the desired water temperature. This results in higher energy consumption and decreased efficiency.
• Prolonging the Lifespan: Limescale buildup can damage your water heater’s internal components, potentially leading to costly repairs or even the need for a replacement. Regular descaling prevents this damage and extends the life of your unit.
• Preventing Blockages: Limescale buildup can clog water lines within the heater, reducing water flow and causing inconsistent water temperatures or low water pressure.
• Avoiding Costly Repairs: Ignoring descaling can result in issues that require expensive repairs, such as replacing heating elements or internal components. Regular descaling is a simple way to avoid these unnecessary costs.

How Do You Descale a Tankless Water Heater?

Descaling your tankless water heater is a straightforward process that can be done with a few basic tools and these steps:

Step 1: Turn Off the Water Heater

Before you begin, ensure that the water heater’s power and gas, if applicable, are turned off. For electric models, switch off the power at the circuit breaker. For gas models, turn off the gas supply.

Step 2: Shut Off the Water Supply

Locate the hot and cold water isolator valves on your tankless water heater and close them to stop water from flowing into and out of the unit. This isolates the water heater for descaling.

Step 3: Connect a Descaling Pump

You will need a submersible pump, drain hoses, and a bucket filled with a commercial descaling solution. Mix one gallon of water with one pint of the descaling solution. You can also use white vinegar without diluting it. Connect one hose to the hot water and one hose to the cold water service ports on your heater. The cold water inlet will pull the descaling solution into the unit, while the hot water outlet will allow the solution to circulate back out into the bucket.

Step 4: Run the Descaling Solution

Turn on the pump to begin circulating the descaling solution through your tankless water heater. Let the solution circulate for about 45 minutes to an hour. This process will dissolve the limescale and flush it out of the system.

Step 5: Rinse the System

After descaling, turn off the pump and dispose of the used solution. Rinse out the bucket and fill it with clean, cold water. Place the pump back into the bucket and run it for 15 minutes. Repeat this process until the water flows clearly and there is no more scale.

Step 6: Restart the Water Heater

Once the system has been thoroughly flushed, disconnect the hoses from the service ports, close them, and open the cold water and hot water isolator valves. Turn on the power or gas supply to the water heater. Verify the pilot light on the heater is relit. Run the hot water at a faucet to ensure everything works properly, and there are no leaks around your tankless water heater.

When to Get Help From a Professional Plumber

While descaling a tankless water heater is a task that many homeowners can take on, there are some situations where it might be best to call a licensed plumber. Some signs that you might need professional help include:

• Recurring Limescale Buildup: If you’ve descaled your heater but continue to notice problems with water flow, temperature fluctuations, or energy efficiency, a professional plumber can assess the issue and determine if something else is causing the problem.
• Complex Plumbing Setup: If your water heater is connected to a complex plumbing system or if you’re unsure how to access the service ports and valves, call a plumber to avoid damaging your system.
• Unusual Noises or Malfunctions: If your tankless water heater is making strange noises, like rumbling or banging, or malfunctioning before or after descaling, a professional inspection is recommended to prevent further damage.
• Time Constraints or Safety Concerns: If you don’t have the time, tools, or confidence to descale your water heater yourself, a plumber can handle the task safely and efficiently, ensuring that your unit is properly maintained.

Tankless Water Heater Maintenance, Repairs, and Installations in Southern California

Regular maintenance is crucial to keeping your tankless water heater running efficiently and avoiding costly repairs. If you’re uncomfortable descaling your water heater or if you’re experiencing persistent issues, it’s time to call a professional. At Lynch Plumbing, our experienced plumbers specialize in tankless water heater installation, maintenance, and repair services. Contact us today to schedule service in the San Fernando Valley and throughout Los Angeles and Ventura counties.