How Do You Replace a Water Heater Filter?

By Rowan Guthrie

June 18, 2024

Few things are as comforting as a warm shower or a hot cup of tea on a chilly day, and your water heater plays a pivotal role in ensuring that warmth. This means you should keep your water heater functioning optimally, and regular maintenance is vital.

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One aspect some people often overlook is the water heater filter.

How Often Do You Need to Replace a Tankless Water Heater Filter?

Before looking into the replacement process, it's important to understand how frequently you should change the filter in a tankless water heater. Unlike traditional systems that may require periodic flushing, tankless water heaters typically feature filters that need to be replaced less frequently. Generally, you should replace the filter every six months to a year, depending on water quality and usage. However, it's wise to consult your manufacturer's recommendations for specific guidance tailored to your system, as every water heater design is unique.

Step-by-Step: How Do You Replace a Water Heater Filter?

Replacing a water heater filter may seem daunting if you're new to the process, but you may be surprised by how simple it is.

Step 1: Gather Materials

Make sure you have all the necessary tools and materials to hand before you begin so you can complete the job efficiently. You'll typically need:

A new water heater filter cartridge that's compatible with your system
An adjustable wrench or filter wrench
A towel or rag for cleaning up
A bucket to catch any residual water if you don't have a drain nearby, such as a sink

Step 2: Shut off the Water Supply

As with all DIY jobs, think safety first. Locate the shut-off valve for your water heater and turn it off. It’s normally located near the heater, often along the water supply line leading to it. This step prevents water from flowing into the unit while you work, minimizing the risk of leaks or spills.

Step 3: Drain Any Remaining Water

While not always necessary, draining any remaining water from the system can make the process smoother. If your unit has a drain valve, attach a hose and direct it to a suitable drainage area. Open the valve and let the water drain completely. Use a bucket if there isn’t a nearby drainage area.

Step 4: Locate and Remove the Old Filter

Depending on your tankless water heater model, the filter may be inside the unit or attached to the water inlet valve. Use your wrench to loosen and remove the filter housing. Be prepared for a small amount of water or sediment to escape when removing the old filter. If possible, lay the towel or rag underneath your work area to soak up any drips.

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Step 5: Install the New Filter

Take your new water heater filter cartridge and insert it into the filter housing, ensuring it's seated properly. If the filter is directional, pay attention to the arrows indicating the correct flow direction. Once in place, reattach the filter housing securely using your wrench.

Step 6: Turn the Water Supply Back On

Slowly turn the shut-off valve back on and check for leaks around the filter housing. Don’t turn the valve back on too quickly because you'll risk a sudden surge in water pressure, which has the potential to damage your water heater pipes and components. Tighten connections if necessary.

Step 7: Check for Proper Operation

When water flow is restored, it's common for air pockets to form in the pipes, especially if the system has been drained. To purge air from the lines, open a nearby hot water faucet and let it run for a few minutes until the water flows smoothly and without sputtering. This helps ensure proper circulation and prevents airlocks in the system.

Step 8: Clean up and Maintenance

Dispose of the old filter cartridge responsibly and tidy up any spilled water or debris. Note the replacement date for future reference, and consider setting a reminder on your phone for the next filter replacement to ensure consistent maintenance.

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