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Clean Tankless Water Heater Water Filter and Air Filter

Materials Cost: FREE
Difficulty Level: 1

Introduction

Tankless water heaters contain an air filter and a water filter screen, which require regular cleaning.

Why

Tankless water heaters have two filters – an air filter and a water filter. Cleaning these filters on your tankless water heater every 6-12 months ensures the highest efficiency and performance. For example, if the air intake filter becomes clogged with dust or debris, the water heater will stop working until the air filter is cleaned.

What You'll Need

  • Soft bristled brush
  • Dish soap
  • Lint-free towel
  • Pliers (optional)
  • Toothpick or cotton swab

1. Turn off the water heater.

Instructions are provided below for electric water heaters and gas water heaters. Consult the instruction manual for specific instructions and filter locations for your model.

Electric: Unplug the unit from the wall. Remove the front cover, as shown in Figure 1.

Gas: Turn off the power to the unit. Wait for the water heater to cool down. Close the manual gas shutoff valve. Then open the water heater unit. Consult the manufacturer’s instructions to ensure proper shutdown.

Figure 1. Use a screwdriver to remove the front panel of a tankless water heater to access the air filter or other internal components (Source: PNNL).

2. Remove Air Filter

Locate the air filter and remove it. If you cannot locate the air filter, consult the product specifications for your water heater. Figure 2 shows the location of the air filter in two different tankless water heaters. Air filters come in various shapes, depending on the model (Figures 3 and 4). The filter is often located near the top of the water heater between the air intake pipe and the fan.

Figure 2. The white arrows indicate the location of the air filters in two different tankless water heaters (Source: PNNL).
Figure 3. In some tankless water heater models, the air filter is clearly labeled; this reusable filter slides out of its slot for easy cleaning (Source: PNNL).
Figure 4. Bugs managed to get trapped in the air filter of this tankless water heater (Source: PNNL).

3. Clean Air Filter.

Gently scrub the air filter with a soft bristled brush and a mild dish soap solution, as shown in Figure 5. Rinse the air filter with clean water and dry with a lint-free towel or air dry. Re-install the air filter. Next clean the water filter.

Figure 5. Clean the air filter of your tankless water heater with soapy water and a soft bristled brush (Source: PNNL).

4. Shut off and Drain Tank.

Electric: Close the cold-water inlet valve. Figure 6 shows an example of the water inlet valve. The location of the valve will be specified by the manufacturer.

Gas: Close the water inlet valve. 

Turn on hot water faucets in the house to drain residual water from the tank. Once the flow subsides, turn off the faucets.

Figure 6. Close the water inlet valve before cleaning the water line filter on this tankless water heater (Source: PNNL).

5. Remove Water Line Filter.

Locate the water line filter above the water inlet valve and place a bucket beneath to catch any water still in the unit. The filter has a black cap and can be unscrewed manually, as shown in Figure 7. If the filter cap is too tight, gently use a set of pliers to loosen it. 

Figure 7. Loosen the cap to remove the water line filter on this tankless water heater (Source: PNNL).

6. Clean the Water Filter.

Gently tap the water filter to dislodge debris (Figure 8). Use a cotton swab, toothpick, or old toothbrush to remove debris from the filter (Figure 9). Place the filter under running water to clean further.

Figure 8. This water filter from a tankless water heater is very clogged with debris (Source: PNNL).
Figure 9. An old toothbrush works great for cleaning the inlet water filter on a tankless water heater (Source: PNNL).

7. Re-Install the Water Filter.

Screw the water filter back into place; hand tighten only.

8. Turn the Water Heater On.

Electric: Turn the water inlet back on by turning the valve. Ensure no water leakage occurs from the filter. Plug the water heater back in and turn on.

Gas: Turn the water inlet back on by turning the valve. Turn the manual gas shutoff valve back on. Power the water heater back on.

Consult the instruction manual for specific instructions for your model.

Additional Info

Videos

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Tankless Water Heater

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Author(s)
Home Innovation Research Labs
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Home Innovation Research Labs
Description
Video from Home Innovation Research Labs giving a background on efficient tankless water heaters.
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Disclaimer

This content is a work created with funding provided by the United States Department of Energy under Contract no DE-AC05-076RL01830 for the operation of Pacific Northwest National Laboratory. The information and guidance provided by Pacific Northwest National Laboratory (PNNL) in the content are intended solely for educational purposes only and do not constitute formal training or certification. It is provided with the explicit understanding that neither the United States Government nor the United States Department of Energy, nor the Contractor, nor any or their employees, nor any jurisdiction or organization that has cooperated in the development of these materials, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness or any information, apparatus, product, software, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof, or Battelle Memorial Institute. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Viewers assumes full responsibility for all actions that they may take from information provided in this content including ensuring the safety, code compliance, and proper functionality of any products they choose to install. Installation and use of such products should be performed in accordance with local regulations and manufacturer instructions.