How to Winterize a Tankless Water Heater and Protect the Plumbing System

To properly prepare your tankless water heater for winter, it’s essential to take a few key steps to prevent damage from freezing temperatures.

Understanding how to winterize a tankless water heater ensures that your system stays functional and safe throughout the colder months. By following these guidelines, you can avoid costly repairs and maintain efficient performance.

How to Winterize a Tankless Water Heater: Tips to Prepare for Winter

Despite the presence of freeze protection features, all tankless water heaters rely on electric power, including the protection system (usually a heating element or sensor). In the event of a power outage, your tankless unit will fail. This was experienced by many people during the “arctic” winter at the end of 2017.

This is why it is crucial to properly winterize your tankless water heater and be prepared for cold days.

According to experts and many homeowners who have already taken action, the most effective way to prevent freezing during winter is by installing a tankless water heater in a heated room with wind-resistant features.

Nearly every tankless heater manufacturer specifies that the unit should not be installed in areas where the temperature can drop to 36°F or lower. Failure to take proper precautions, such as correct draining, may result in damage to the tankless unit and its components, which will not be covered under warranty. Additionally, adding an anti-freeze solution is not recommended, as it can cause damage to the heater’s components.

This is especially important if the tankless water heater is installed in locations like cabins, garages, or if you will be absent for an extended period.

Can Tankless Water Heaters Freeze?

Yes, tankless water heaters can freeze if proper precautions are not followed. While many modern models are equipped with freeze protection systems, such as electric heaters, they still rely on a consistent power supply to function effectively.

These heaters are installed on the heat exchangers and other internal components, activating when the temperature drops below a specific threshold to prevent freezing and damage to the unit. Some models periodically heat a small amount of water to keep the system frost-free.

It’s important to note that without power, the freeze protection features will be disabled. Additionally, manufacturers recommend installing a flue damper to minimize cold air entering through the venting system and insulating exposed pipes for added protection.

Most models from reputable brands like Rheem, Takagi, Noritz, and Rinnai protect the unit from freezing, with indoor models typically offering protection down to -22°F (without wind exposure) and outdoor models providing protection down to -5°F.

Winterizing a Tankless Water Heater: Step-by-Step Guide

So, how do you prepare a tankless water heater for winter?

• Turn the power off. Begin by turning off the electrical power and gas supply. Shut off the gas supply by using the main valve on the gas supply line. For electricity, either unplug the power supply cord or switch off the power at the breaker panel. If the unit has a display on the front, it should be black with no lights.
• Wait until water cools down. It is important to note that there may still be some hot water inside the unit. If the unit was recently in operation before draining, wait for the hot water to cool down before proceeding.
• Turn off water. Shut off the water supply to the tankless water heater by closing the main shut-off valve. This ensures that no additional water enters the system during the winterization process.
• Drain the system. Open all the hot water taps in your home to allow the system to drain and release any remaining water and pressure from the plumbing system. This step is crucial to prevent water from freezing and causing damage.
• Disconnect the pipes. Carefully disconnect the incoming and outgoing water pipes from the tankless water heater. This ensures that there are no water connections to the unit during the winter months.
• Remove the inlet water filter. Locate the inlet water filter on your tankless water heater and remove it. This allows for proper draining and prevents any debris from accumulating inside the unit.
• Ensure all water from the unit is removed. To ensure that all water is removed from the tankless water heater, use a bucket or container to collect any residual water. During the draining process, make sure that the system fully empties, leaving no water behind.

Some manufacturers recommend using air compressors to blow short bursts of air through the inlet connection to ensure that no water remains inside the heater.

By following these steps, your tankless water heater will be free of water and fully winterized.

Tips to Consider

• Vent Pipe Direction: Whether you’re installing a concentric or dual-vent system, avoid facing the vent pipes in the wind direction, as the “wind chill” effect can lower the temperature.
• Condensate Drain Tubing: Ensure condensate drain tubing is not installed in areas where it might freeze. It is recommended to install the drain pipe inside the wall for better protection.
• Negative Draft and Freezing Components: Tankless water heater components, especially the heat exchanger, can freeze due to negative draft in the venting. This happens when gas-powered devices, like a furnace, draw air from the water heater’s vent pipe, allowing cold air to enter the system and freeze the water in the heat exchanger.
• Solution for Negative Draft: To address negative draft, ensure a sufficient supply of combustion air for all gas-powered appliances in the building. This will help prevent freezing.
• Backdraft Reducer: Some manufacturers recommend using a backdraft reducer, which closes the internal flapper to limit backdraft and protect the unit.
• Protecting the Unit in Freezing Weather: In freezing conditions, protect the unit by opening the hot water tap and allowing a small stream of hot water to run (about 4 mm thick). Before doing so, turn off the power and close the gas supply valve. This helps protect both the heater and the piping.

Can I Fix a Frozen Tankless Water Heater (Unfreeze)?

If your tankless water heater becomes frozen, it is crucial to address the issue promptly and take steps to unfreeze it. The accumulation of ice can cause damage to internal components, particularly those made of plastic, as well as sensors and electronics.

Here are the steps to thaw out your tankless water heater:

1. Start by checking if your tankless unit or pipes are frozen. Look for any signs of frost or ice accumulation on the unit itself or along the pipes.
2. If you find that a pipe is frozen, you can use a hair dryer to defrost it. Apply gentle heat along the length of the frozen section, moving the hair dryer back and forth until the ice melts and the pipe is clear.
3. Before proceeding further, close the gas and water supply to the tankless water heater. This will prevent any potential leaks or water flow while you work on thawing out the unit.
4. Turn off the power to the tankless water heater by flipping the breaker to the off position. This ensures your safety and prevents any electrical mishaps during the process.
5. Next, carefully disconnect the unit from its installation and move it to a warmer room if possible. Alternatively, you can apply gentle heat using the hair dryer to warm up the surrounding area of the tankless water heater. It’s important to avoid applying excessive heat directly to sensitive elements like the heat exchanger, as it can cause damage.
6. Open a hot water tap connected to the tankless water heater. This will allow the flow of water through the system and aid in the thawing process.
7. Patience is key at this stage. Wait until the entire system thaws completely, ensuring that all ice has melted and water can flow freely.
8. While the system thaws, carefully inspect the tankless water heater for any signs of leaks or damages. Look for any cracks, broken components, or other visible issues that may require repair or replacement.
9. Once the system is completely thawed and inspected, drain all the water from the tankless water heater. This helps remove any residual water that may have accumulated during the freezing process.
10. If everything appears to be in order with the unit and no major damages or leaks are found, reinstall the tankless water heater in its original position.
11. Open the gas and water valves to restore the supply to the tankless water heater.
12. Finally, turn the power back on by flipping the breaker to the on position. Ensure that the unit powers up correctly and operates normally.

By following these detailed steps, you can effectively thaw out a frozen tankless water heater and address any potential issues caused by freezing. Remember to prioritize safety and seek professional assistance if you are uncertain or uncomfortable with performing these steps yourself.

Conclusion

While many tankless water heater manufacturers offer models with built-in protection against freezing, it is still advisable to winterize the unit, especially when away from home or during extended periods of inactivity. Unlike tank-type models, tankless water heaters require more attention and extra care due to their delicate features.

Understanding how to winterize a tankless water heater is crucial for preventing freezing and potential damage.

By following the appropriate steps to drain and protect the unit from cold weather, you can ensure its longevity and reliability.

However, if your tankless water heater does become frozen, it is essential to address the issue promptly and take the necessary steps to unfreeze and repair it.

By taking a proactive approach to winterization and addressing freezing issues, you can maintain optimal performance and enjoy uninterrupted hot water supply throughout the colder months.

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