How To Keep Tankless Water Heater From Freezing?

A tankless water heater is a modern marvel that provides on-demand hot water efficiently and cost-effectively. However, during the frigid winter months, the risk of it freezing is a concern. In this comprehensive guide, we will explore ways to safeguard your tankless water heater from freezing and ensure it continues to provide hot water even in the harshest winter conditions.

Tankless water heaters are a fantastic solution for providing hot water on demand while saving energy. However, during the winter months, they are susceptible to freezing, which can result in inconvenience and costly repairs. To keep your tankless water heater running smoothly throughout the winter, you must take preventive measures.

Understanding the Risks

Before delving into prevention techniques, it’s essential to understand why tankless water heaters are susceptible to freezing. These heaters operate differently from traditional tank-based systems. While the on-demand heating provides many benefits, it can also leave the internal components vulnerable in cold weather. The heat exchanger and water lines may freeze when left unattended, causing damage.

Importance of Preventing Freezing

Preventing freezing in your tankless water heater is not just about maintenance – it’s about protecting your investment. Here are some compelling reasons to take the necessary precautions:

Costly Repairs

When your tankless water heater freezes, the aftermath can be financially painful. The cold weather can cause significant damage, often necessitating costly repairs. Here’s what you might be facing:

Component Replacement

The intricate components of a tankless water heater can suffer severe damage when they freeze. Heat exchangers, sensors, valves, and other vital parts may become dysfunctional. Replacing these components is not only a complex process but also an expensive one. Your bank account may take a considerable hit.

Professional Service Costs

Bringing in a professional to repair your frozen tankless water heater comes with service fees. These experienced technicians must diagnose the issue, disassemble the unit, and install new components. Each step adds to the overall cost.

Unexpected Expenses

Furthermore, repair costs are often unforeseen expenses. You budget for your utilities, but when your water heater malfunctions due to freezing, you’ll need to allocate funds for a sudden, unexpected repair.

Interruption of Service

The most immediate and uncomfortable consequence of a frozen tankless water heater is the interruption of hot water service, especially during the frigid winter months.


Imagine stepping into a cold shower during the winter. It’s an uncomfortable and unwelcome experience. Whether it’s washing dishes, taking a warm bath, or simply having hot water for daily tasks, a frozen water heater can disrupt your daily routine and make life much less comfortable.

Unwanted Discomfort

Heating your home during the winter is a necessity for comfort. However, if your tankless water heater fails due to freezing, you might find yourself without hot water for heating. This situation can lead to discomfort, particularly if you have no alternative heating system in place.

Extended Lifespan

While the consequences of a frozen tankless water heater can be dire, preventing freezing can lead to a more positive outcome – a longer lifespan for your water heater. Here’s how:

Reduced Frequency of Replacements

When you protect your tankless water heater from freezing, you extend its lifespan. By maintaining the unit’s integrity and functionality, you decrease the need for frequent replacements. A well-cared-for water heater can serve you for many years without the need for a costly upgrade. This not only saves you money in the long run but also reduces the environmental impact of manufacturing and disposing of water heaters.

In summary, the financial strain of costly repairs, the inconvenience of service interruption, and the benefits of a longer lifespan underscore the significance of preventing tankless water heater freezing. Investing in preventive measures can not only save you money but also preserve your comfort and peace of mind during cold winter months.

Preventive Measures

Let’s dive into the preventive measures that will shield your tankless water heater from freezing:


Proper insulation is your first line of defense. Insulate both the water lines and the heater itself. For the water lines, consider using pipe insulation to keep the water warm during its journey through your plumbing. For the heater, invest in a specialized tankless water heater cover. These covers are designed to protect against extreme temperatures, ensuring your unit remains operational.

Use Freeze Protection Kits

Freeze protection kits, which include copper components, are designed to monitor the temperature around your tankless water heater. If the temperature drops to a critical point, the kit activates the heater to prevent freezing. These kits are particularly useful in regions with extremely cold climates.

Scheduled Maintenance

Regular maintenance is key. It’s important to have your tankless water heater inspected by a professional at least once a year. They can ensure that all components are functioning correctly and that there are no leaks or issues that could contribute to freezing.

Keep Tankless water heater from freezing 

1. Insulation is Key: Protecting Your Heater from the Cold

To keep your tankless water heater from freezing, start by insulating the unit itself. Water heater blankets or covers are designed specifically for this purpose. They help in retaining heat and preventing the unit from dropping below-freezing temperatures. Additionally, if your water heater is located in an area exposed to the cold, consider using both pipe insulation and a water heater blanket for added protection.

2. Seal Cracks and Gaps: Weatherproofing the Surrounding Area

Inspect the area around your water heater for cracks or gaps that might allow cold air to seep in. Utilize weatherproofing materials such as weather stripping, caulk, or expanding foam to seal these openings. This simple step can go a long way in retaining the heat and preventing your tankless water heater from freezing.

3. Adjust the Temperature: Ward Off Freezing Temperatures

During winter, consider increasing the temperature setting on your tankless water heater. By setting it a few degrees higher, you ensure that the water inside the unit remains warm, reducing the risk of freezing. However, be cautious not to set it too high, as this could lead to scalding water.

4. Freeze Protection Kits: A Preventive Measure

Some tankless water heaters come with freeze protection kits. These kits are equipped with a heating element that activates when temperatures drop significantly. This additional heat source prevents freezing and ensures your water heater continues to operate smoothly.

5. Drain the Water Heater: A Preventative Measure for Extended Freezing Periods

If you expect an extended period of sub-zero temperatures and your tankless water heater won’t be in use, consider draining it. Draining removes the water from the unit, eliminating the risk of freezing. When doing this, follow the manufacturer’s instructions to avoid any damage to your water heater.

6. Strategic Placement: Choose a Location Wisely

When installing a tankless water heater, opt for a location that is less exposed to cold drafts and extreme temperatures. Placing it in a heated area or using a space heater can help maintain a consistently warmer environment for your water heater.

7. Recirculation Systems: Keeping Water Moving

A recirculation system constantly circulates warm water through your plumbing, reducing the chances of freezing in the pipes or the tankless water heater itself. This is especially useful in preventing frozen pipes.

8. Regular Maintenance: Stay Ahead of Freezing

Routine maintenance is crucial. Clean or replace filters as needed and check for any issues that might lead to freezing. A well-maintained water heater is less likely to develop problems.

By following these proactive steps, you can prevent your tankless water heater from freezing and enjoy uninterrupted hot water even during the harshest winter conditions. Protecting your investment by insulating, sealing gaps, and practicing good maintenance ensures that your tankless water heater remains functional and provides hot water whenever you need it. Don’t wait until winter is in full swing; take these precautions to keep your tankless water heater in top working condition.

Summary Table: Safeguarding Your Tankless Water Heater from Freezing

1. InsulationUse water heater blankets and pipe insulation.
2. Seal Cracks and GapsEmploy weatherproofing materials to seal openings.
3. Adjust TemperatureIncrease temperature slightly during winter.
4. Freeze ProtectionConsider units equipped with freeze protection kits.
5. Drain the HeaterIf not in use, follow manufacturer’s instructions to drain.
6. Strategic PlacementChoose a less exposed location for installation.
7. Recirculation SystemKeep water moving to prevent frozen pipes.
8. Regular MaintenanceConduct routine maintenance for a well-functioning unit.


Can I use a regular water heater blanket for my tankless water heater?

While it is not recommended, a regular water heater blanket can provide some insulation for a tankless unit.

How low can the temperature drop before my tankless water heater freezes?

Most tankless water heaters are designed to withstand temperatures as low as -30°F, but it’s best to take preventive measures before reaching such extremes.

Is it safe to drain my tankless water heater for an extended period?

Draining your tankless water heater for a few days or weeks is safe, but consult your manufacturer’s guidelines for longer durations.

Are freeze protection kits available for all tankless water heaters? 

No, not all tankless water heaters come with freeze protection kits. Check with the manufacturer or consider retrofitting a kit if necessary.

Is a recirculation system beneficial in preventing frozen pipes during winter? 

Yes, a recirculation system can keep water moving, reducing the risk of frozen pipes in colder regions.


In conclusion, safeguarding your tankless water heater from freezing is a crucial step in maintaining its efficiency and prolonging its lifespan. With the proactive measures outlined in this article, such as proper insulation, sealing gaps, temperature adjustments, and considering freeze protection kits, you can prevent costly repairs and ensure uninterrupted hot water during cold winter months. 

Ensuring your tankless water heater remains free from freezing is vital to maintaining its functionality and extending its lifespan. By understanding the risks, the importance of prevention, and implementing the right measures, you can enjoy the convenience of hot water throughout the winter months. Don’t wait until the temperatures plummet – act now to safeguard your tankless water heater.

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