Top 5 Tankless Water Heater Maintenance Tips

By Tony Escamilla

Tankless water heaters are becoming increasingly popular due to their energy efficiency and space-saving benefits. However, like all appliances, they require regular maintenance to function properly and efficiently over time. Here are some maintenance procedures for tankless water heaters:

Tools You Will Need

To flush a tankless water heater, you can purchase a kit or you will need the following tools:

1. Bucket or container: You will need a bucket or container to collect the water and debris that is flushed out of the unit.
2. Pump: You will need a pump to circulate the descaling solution through the tankless water heater. You can use a small submersible pump, a utility pump, or a specialized descaling pump.
3. Descaling solution: You will need a descaling solution to remove any mineral buildup or sediment in the heat exchanger. You can use a commercial descaling solution designed specifically for tankless water heaters or make your own using white vinegar.
4. Hoses: You will need hoses to connect the pump to the tankless water heater and drain the descaling solution and water from the unit. Make sure to use hoses that are compatible with hot water and can withstand the pressure of the pump.
5. Wrench: You may need a wrench to remove the drain valve on the tankless water heater to facilitate flushing.
6. Protective gear: You should wear protective gear, including gloves, safety glasses, and a face mask, to protect yourself from the descaling solution and any debris that may be flushed out of the unit.

Before you begin flushing your tankless water heater, make sure to consult the owner's manual for specific instructions and safety precautions. If you're not comfortable performing the maintenance yourself, it's best to hire a professional plumber.

Check and clean the air filter

Tankless water heaters operate by using a heat exchanger to quickly heat water as it flows through the unit. The heat exchanger requires a steady supply of fresh air to function properly. However, this air supply can become restricted if the air intake filter becomes clogged with dust, debris, or other particles. This can cause the unit to work harder than it needs to, reducing its efficiency and potentially leading to malfunctions. To prevent these issues, it's important to check the air filter on your tankless water heater regularly and clean it as needed. The frequency of cleaning depends on the environment in which the unit is located. For example, if it's installed in a dusty or dirty area, it may require more frequent cleaning. In general, aim to check the filter every six months and clean it as necessary. To clean the air filter, follow these steps:

1. Turn off the power to the unit: Before cleaning the filter, make sure to turn off the power to the tankless water heater. This will ensure your safety and prevent any damage to the unit.
2. Locate the air filter: The air filter is usually located on the bottom or side of the unit. Consult your owner's manual for specific instructions on where to find the filter.
3. Remove the filter: Depending on the model of your tankless water heater, you may need to use a screwdriver or other tool to remove the air filter. Once removed, inspect the filter for any signs of damage or excessive buildup.
4. Clean the filter: If the filter is dirty, use a soft brush or vacuum cleaner to gently remove any dust or debris. Alternatively, you can rinse the filter with water, but make sure to let it dry completely before reinstalling it.
5. Reinstall the filter: Once the filter is clean and dry, carefully reinstall it in the unit. Make sure it fits snugly and securely in its housing.

Flush the system

Over time, minerals, sediment, and other debris can accumulate in the tankless water heater's heat exchanger, causing it to lose efficiency and potentially leading to malfunctions. Flushing the system regularly can help remove these deposits, keeping the unit running smoothly and extending its lifespan. Here's how to flush a tankless water heater:

1. Turn off the power to the unit: Before flushing the system, make sure to turn off the power to the tankless water heater. This will ensure your safety and prevent any damage to the unit.
2. Shut off the water supply: Locate the shut-off valves for the cold water supply and hot water output lines to the tankless water heater. Close both valves to stop the flow of water to the unit.
3. Drain the unit: Open the drain valve at the bottom of the tankless water heater and drain all the water from the unit. You can use a bucket or hose to collect the water.
4. Connect a descaling solution: Once the tankless water heater is drained, connect a descaling solution to the cold water inlet valve. Follow the manufacturer's instructions for the specific solution you're using.
5. Run the descaling solution through the unit: Turn on the cold water supply and let the descaling solution run through the tankless water heater for the recommended amount of time, usually around 45 minutes.
6. Flush the system: After the descaling solution has run through the unit, turn off the cold water supply and drain the tankless water heater again. Flush the unit with clean water until all traces of the descaling solution have been removed.
7. Restore power and water supply: Once the system has been flushed and drained, close the drain valve and open the shut-off valves for the cold water supply and hot water output lines. Turn on the power to the unit.

Alternatively, you can hire a professional plumber to flush the tankless water heater for you. They will have the necessary tools and expertise to complete the job quickly and safely. By flushing the system regularly, you can remove any buildup in the heat exchanger and keep your tankless water heater running efficiently and reliably for years to come.

Check the pressure relief valve

The pressure relief valve is a critical safety feature that protects your tankless water heater from potentially dangerous overpressure situations. It is designed to open and release pressure if the pressure inside the unit exceeds a certain level. If the valve is faulty or not functioning properly, it can put your tankless water heater at risk of damage or even explosion. Here's how to check the pressure relief valve:

1. Turn off the power to the unit: Before checking the pressure relief valve, make sure to turn off the power to the tankless water heater. This will ensure your safety and prevent any damage to the unit.
2. Locate the pressure relief valve: The pressure relief valve is usually located on the top or side of the tankless water heater. Consult your owner's manual for specific instructions on where to find the valve.
3. Inspect the valve: Check the pressure relief valve for any signs of damage, such as corrosion or leaking. If you notice any issues with the valve, it may need to be replaced.
4. Test the valve: To test the pressure relief valve, lift the lever on the valve slightly and release it. You should hear a rush of air as the valve opens and closes. If you don't hear anything, the valve may be stuck or not functioning properly.
5. Replace the valve: If the pressure relief valve is damaged or not functioning properly, it should be replaced immediately. Consult your owner's manual or contact a professional plumber for guidance on how to replace the valve.

Inspect the venting system

Proper ventilation is essential for the safe operation of tankless water heaters. The venting system allows for the safe disposal of exhaust gases produced by the unit. If the venting system becomes blocked or damaged, it can affect the performance of the unit and even pose a safety hazard. Here's how to inspect the venting system:

1. Turn off the power to the unit: Before inspecting the venting system, make sure to turn off the power to the tankless water heater. This will ensure your safety and prevent any damage to the unit.
2. Locate the venting system: The venting system is usually located on the top or side of the tankless water heater. It consists of a vent pipe that runs from the unit to the outside of your home.
3. Inspect the vent pipe: Check the vent pipe for any signs of damage or blockages. Look for cracks, holes, or other damage that could allow exhaust gases to leak into your home. Also, check for any debris or other blockages that could obstruct the flow of exhaust gases.
4. Check the vent hood: The vent hood is located on the exterior of your home where the vent pipe terminates. Check the vent hood for any blockages or damage that could affect the venting system's performance.
5. Hire a professional plumber: If you notice any issues with the venting system, it's best to hire a professional plumber to repair them. They will have the necessary tools and expertise to diagnose and fix any problems with the venting system safely.

Check the Water Temperature

Checking the water temperature is an important part of tankless water heater maintenance. It ensures that the unit is heating water to the desired temperature and that the temperature setting is adjusted to prevent scalding or insufficient hot water. Here's how to check the water temperature:

1. Turn on a hot water faucet: Turn on a hot water faucet in your home and let the water run for a few minutes. This will allow the tankless water heater to start heating the water.
2. Use a thermometer: Use a thermometer to measure the temperature of the hot water coming out of the faucet. Make sure to hold the thermometer in the stream of water to get an accurate reading.
3. Check the temperature setting: Check the temperature setting on the tankless water heater to ensure it matches the temperature of the water coming out of the faucet. If the temperature is too high, adjust the setting to prevent scalding. If the temperature is too low, adjust the setting to ensure you have enough hot water for your needs.
4. Repeat the process: Repeat this process periodically to ensure that the temperature setting remains accurate and adjusted as needed.

It's important to note that the maximum safe temperature for hot water is 120°F (49°C). Any higher than that can cause serious burns, especially in children and the elderly. If you have small children or elderly individuals in your home, consider setting the temperature lower to prevent accidental burns.

Schedule professional maintenance

Consider scheduling a professional maintenance check at least once a year. A professional plumber can perform a comprehensive inspection of the unit, clean the heat exchanger, and ensure everything is functioning properly. By following these maintenance procedures, you can keep your tankless water heater in good condition and enjoy reliable hot water for years to come.