Cleaning & Descaling Your Tankless Water Heater

Like any home appliance, your tankless water heater needs some TLC to keep it in top-notch condition. This includes regular cleaning to avoid mineral buildup and ensure energy efficiency. This detailed guide offers step-by-step instructions on how to clean and descale a tankless water heater. But first, let's understand why it's so crucial and what tools you need.

Why Cleaning Your Tankless Water Heater is Important

A tankless water heater needs a good cleaning and descaling to function at its best. Over time, mineral deposits can build up, especially in hard water areas. This buildup interferes with heat transfer, leading to reduced efficiency and increased energy use.

Regular cleaning and descaling prevents issues such as reduced water flow, insufficient hot water supply, fluctuating water temperatures, and even system malfunctions.

So, how do you clean and descale a tankless water heater? Let's dive into the process.

Tools Needed for Cleaning

Cleaning a tankless water heater starts with gathering the right tools. You'll need:

• Soft brush or sponge.
• 5-gallon bucket.
• 1/6 HP submersible pump.
• Set of washer fill hoses.
• Garden hose.
• Descaling solution or 2 gallons of white vinegar.
• Towels.
• Protective gloves and safety goggles.
• Channel-lock pliers.

Note: You can also buy a descaling kit that will have many of the essential supplies listed above such as the pump, hoses, bucket and descaling solution. Buying the kit is typically more expensive but also more convenient that buying the items separately.

Before you start, ensure the power and water supply to the heater are turned off, along with the gas supply if applicable. Always follow the manufacturer's instructions for safety precautions.

Step-by-Step Guide on How to Clean a Tankless Water Heater

Follow this step-by-step procedure to clean and descale a tankless water heater:

1. Shut Off Power, Gas and Water Supply

Start by turning off the power supply at the house circuit breaker for the water heater. Shut off the gas supply if you have a gas water heater. Next, shut off the cold water supply valve and hot water outlet valve.

2. Drain the Water Heater

Remove the service cap of the cold inlet valve and attach a garden hose to the fitting. (You may need to use the channel lock pliers to remove the service cap and tighten the garden hose.) Direct the other end to a suitable drainage area. Open the drain valve to empty the unit, then close it and disconnect the garden hose.

3. Clean the Heat Exchanger

Follow the manufacturer's instructions to carefully remove the cover of the heat exchanger. Use soft brushes or cloths to clean it, ensuring all dust, debris, and sediment are removed. Reinstall the heat exchanger cover.

4. Descale the Water Heater

Use a manufacturer-recommended descaling solution or white vinegar to dissolve mineral deposits. Follow the instructions provided with the descaler so mix the solution. Thoroughly rinse the solution or vinegar from water heater afterwards. Here’s the basic descaling procedure:

1. Place a five-gallon bucket on the floor or a chair near the water heater. Fill the bucket with 2 gallons of white vinegar or descaling solution.
2. Connect one washer fill hose to the submersible pump and the other end to the inlet water service valve fitting. Place the submersible pump in the bucket. Open the Water Inlet Service Valve to allow water to flow into the water heater through the hose connected to water inlet service valve fitting.
3. Remove the service cap from the hot water outlet service valve. Connect the 2nd washer fill hose to the fitting and place the other end of the hose in the bucket. Open the Hot Water Service Valve to allow water to flow through the outlet hose and into the bucket.
4. Plug in the pump outlet cord and turn on the pump. It should immediately begin pumping vinegar from the bucket through the heater and back into the bucket in a continuous cycle. Run the pump for 45 minutes. If there’s significant mineral buildup, the vinegar or descaling solution will darken.
5. Shut off the pump and unplug it. Close the cold water inlet service valve and disconnect the hose. Reinstall the service cap and tighten it securely.
6. Close the hot water outlet service valve and disconnect the hose. Connect the garden hose to the outlet valve and direct the other end of the garden hose to a suitable drainage area. Open the outlet service valve.

5. Flush the Water Heater

1. Open the water heater inlet valve to flush supply water through unit and out through the garden hose for 3 minutes or until water draining out the garden hose is clean and clear.
2. Turn off the water supply inlet valve and the outlet service valve.
3. Disconnect the garden hose and reinstall the outlet service cap. Tighten the cap securely.
4. Open the cold water inlet valve and hot water outlet valve. Open a hot water faucet inside your home to vent any air out of the hot water heater and shut off the faucet once water flows freely.
5. Restore electrical power and the gas supply to the water heater so it resumes normal operation.

By following these basic instructions to clean a tankless water heater, you can keep your unit running smoothly. Always refer to your specific unit's manual for any manufacturer-specific instructions and recommendations.

Clean and descale your tankless water heater at least once a year or as recommended in your owner’s manual.