Home Maintenance University

Flushing Your Water Heater

Written by MyHomeQB | Dec 10, 2024 4:53:20 PM

How to Flush Your Water Heater: A Step-by-Step Guide

Flushing your water heater is an essential maintenance task that can help extend its lifespan, improve efficiency, and prevent costly repairs. Over time, sediment and mineral deposits can build up inside both tank and tankless water heaters, reducing their efficiency and potentially causing issues. By flushing your water heater regularly, you can keep it running smoothly.

Here’s a step-by-step guide on how to flush both traditional tank-style and tankless water heaters. 

See below for a step-by-step guide on how to do it & why it's important!

Why Flush Your Water Heater?

Sediment buildup from minerals like calcium and magnesium can accumulate at the bottom of your water heater tank. This buildup can cause a variety of issues:

  • Reduced heating efficiency
  • Longer warm-up times
  • Overheating, which can damage the heating element
  • Increased energy consumption
  • The potential for clogs in the plumbing
  • It saves you money - see how here!

For tankless water heaters, though there is no standing water to collect sediment, mineral buildup on the heat exchanger can reduce efficiency and cause malfunctions.

Regular flushing (usually once a year) can help prevent these issues.

Flushing a Tank-Style Water Heater

Tools & Materials Needed:

  • Garden hose
  • Bucket (optional)
  • A flathead screwdriver or wrench (for draining valve)
  • Towel (for spills)
  • Gloves (optional)

Step-by-Step Instructions:

  1. Turn off the Power and Water Supply:

    • Electric Water Heater: Switch off the circuit breaker that powers your water heater.
    • Gas Water Heater: Turn the gas valve to the "OFF" position.
    • Turn off the cold water supply to the tank. This is usually done by closing the valve on the cold water pipe leading into the water heater.

  2. Connect a Hose to the Drain Valve:

    • Find the drain valve near the bottom of the tank (often on the side or bottom).
    • Attach a garden hose to the drain valve. Ensure the hose is securely attached, and the other end of the hose is positioned outside or into a bucket.

  3. Open the Hot Water Faucet:

    • Open a hot water faucet in your home. This will help relieve pressure in the tank and allow the water to drain more easily.

  4. Drain the Tank:

    • Slowly open the drain valve. Water will begin to flow through the hose. Be cautious, as the water may still be hot.
    • Let the tank drain completely, which can take several minutes.

  5. Flush the Tank:

    • Once the tank is drained, turn the cold water supply valve back on for a few seconds to flush out any remaining sediment. The water will be pushed out through the hose.
    • Repeat this flushing process until the water runs clear, meaning most of the sediment has been flushed out.

  6. Close the Drain Valve:

    • Once the water runs clear, close the drain valve and disconnect the hose.

  7. Refill the Tank:

    • Close the hot water faucet and open the cold water supply valve again to refill the tank.
    • Allow the tank to refill completely before turning the power or gas back on.

  8. Restore Power/Gas:

    • Electric Water Heater: Switch the circuit breaker back on.
    • Gas Water Heater: Turn the gas valve back to the "ON" position.

  9. Check for Leaks:

    • After the tank is refilled and the system is back on, check for any leaks around the drain valve or other connections.

Flushing a Tankless Water Heater

Flushing a tankless water heater is slightly different from flushing a traditional tank water heater. Tankless models use a heat exchanger that can become clogged with mineral deposits, especially in areas with hard water.

Tools & Materials Needed:

  • A pump (submersible or a specialized descaling pump kit)
  • White vinegar or a descaling solution
  • Hoses to connect the pump to the water heater
  • Wrench (for disconnecting the water lines)

Step-by-Step Instructions:

  1. Turn Off Power and Water Supply:

    • Electric Tankless Heater: Turn off the power to the unit via the circuit breaker.
    • Gas Tankless Heater: Turn off the gas supply.
    • Turn off the cold and hot water supply valves connected to the tankless unit.

  2. Disconnect the Water Lines:

    • Using a wrench, disconnect the cold and hot water supply lines from the tankless heater.

  3. Set Up the Pump and Vinegar:

    • Place a submersible pump into a bucket and fill it with about 2-3 gallons of white vinegar or descaling solution.
    • Connect one hose from the pump to the cold water inlet and the other to the hot water outlet of the tankless water heater.

  4. Flush the Heater:

    • Turn on the pump and allow it to circulate the vinegar or descaling solution through the system. Let the solution run for about 45 minutes to an hour, ensuring it reaches all areas of the heat exchanger.
    • After the descaling time is up, turn off the pump.

  5. Rinse the System:

    • After descaling, remove the vinegar solution and replace it with clean water in the bucket.
    • Run the pump again with fresh water for about 5-10 minutes to rinse the system thoroughly and clear out any remaining vinegar or sediment.

  6. Reconnect Water Lines:

    • Disconnect the hoses and reconnect the cold and hot water lines to the tankless water heater.

  7. Turn the Water and Power Back On:

    • Turn the cold and hot water supply valves back on and check for leaks.
    • Turn the power (or gas) back on and allow the system to return to normal operation.

  8. Check Functionality:

    • Test the water heater by running hot water at a faucet and checking if the temperature and pressure are consistent.

How Often Should You Flush Your Water Heater?

  • Tank-style Water Heaters: Flushing once a year is generally sufficient for most homes. If you live in an area with hard water, you might need to do it more frequently.
  • Tankless Water Heaters: It is recommended to flush your tankless water heater once a year, especially if you have hard water. Some manufacturers recommend more frequent flushing, depending on usage and water quality.

Final Thoughts

Flushing your water heater is an easy and cost-effective way to ensure it operates at peak performance. Whether you have a tank or tankless water heater, regular maintenance can prevent issues like sediment buildup, inefficiency, and reduced lifespan. Always follow manufacturer guidelines, and if you’re unsure or uncomfortable performing the task yourself, consider hiring a professional to help.

 

 
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