Choosing a tankless water heater in Europe can be one of the smartest upgrades for your home, especially if you want better energy efficiency, modern comfort, and consistent hot water without relying on a bulky storage tank. Many European households are now switching to tankless systems because they save space, reduce energy waste, and offer a cleaner and more convenient way to heat water on demand.
However, buying the wrong tankless water heater can quickly turn into an expensive mistake. Some homeowners end up with poor water pressure, inconsistent temperatures, high installation costs, or a system that does not match their home’s plumbing and electrical setup. Since European homes vary greatly in building age, water hardness, and heating infrastructure, it is important to make a careful and informed choice.
This guide will walk you through the most common mistakes people make when buying a tankless water heater in Europe, and how to avoid them so you can confidently choose the right solution for your household.
Mistake #1: Choosing a Tankless Water Heater Without Checking Flow Rate Needs
One of the most common buying mistakes is assuming that all tankless water heaters provide the same amount of hot water. In reality, the performance of a tankless system depends heavily on how much water your household needs at the same time.
In European homes, it is common to run multiple hot water sources at once, such as a kitchen sink, a bathroom shower, and a washing machine. If your system is not designed for that level of demand, you may experience temperature drops or weak hot water delivery during peak usage.
Before buying, you should estimate your household’s typical flow rate requirements. A single shower might require around 6 to 10 litres per minute, depending on the showerhead and pressure. A kitchen tap may require 4 to 6 litres per minute. If two people shower at the same time, your demand could easily exceed what a smaller tankless water heater can handle.
Many buyers only consider the number of bathrooms, but the correct approach is to consider how many hot water sources may run simultaneously. A mismatch here is one of the fastest ways to end up disappointed with your purchase.
Mistake #2: Ignoring the Temperature Rise Requirement in Cold Regions
Europe has a wide range of climates, and water inlet temperature can vary significantly between countries and even between seasons. A system that works perfectly in southern Spain may struggle in Norway or northern Germany during winter.
A tankless water heater must heat incoming water to your desired output temperature. This difference is called the temperature rise. If you underestimate how cold your incoming water is, you may end up with lukewarm showers, especially when water flow is high.
Many homeowners in colder European regions assume they can simply buy a compact model and still get strong performance. Unfortunately, colder inlet water requires a more powerful heating system, which usually means a higher capacity electric model or a gas-powered option.
To avoid this mistake, you should always check your average winter inlet water temperature and compare it with the heater’s performance rating. If the specifications are based on mild conditions, the real-world performance may be lower than expected.
Mistake #3: Buying Electric Without Checking Electrical Capacity
Electric tankless water heaters are extremely popular in Europe because they are compact, clean, and easy to integrate into modern homes. However, a major mistake is buying an electric model without confirming if your home’s electrical system can support it.
Many electric tankless water heaters require a high power draw. Some models require 3-phase power, while others may need heavy-duty wiring upgrades. If your home is older, especially in historic European buildings, the electrical panel may not have enough capacity to safely support a powerful tankless water heater.
This mistake often results in unexpected installation costs. Homeowners sometimes buy the heater first, then discover they need a new circuit breaker, upgraded cabling, or even a full panel upgrade. In some cases, they may find that installation is not possible without significant renovation work.
Before buying an electric tankless water heater, it is important to consult an electrician or installer. You should verify your amperage capacity, your wiring condition, and whether your home supports the required voltage and phase configuration.
Mistake #4: Assuming Gas Models Are Always Easy to Install
Gas tankless water heaters can be highly efficient and powerful, especially for larger households. Many European buyers choose gas because it delivers strong hot water flow even in colder climates. However, gas models come with their own installation challenges, and many people underestimate them.
One major requirement is proper ventilation. Most gas-powered systems require a flue or venting system to safely remove combustion gases. Depending on your home’s structure, this can be easy or extremely difficult. Apartment buildings may have strict regulations, and older homes may not have the correct venting route available.
Another issue is gas line sizing. If your existing gas line is not designed for the higher demand of a tankless water heater, it may require resizing or replacement. This adds cost and complexity.
In some European areas, homeowners also need permits or must follow strict building codes. Buying a gas tankless water heater without checking these requirements is one of the biggest mistakes that can delay installation or even force you to return the product.
Mistake #5: Overlooking Water Pressure Requirements
Water pressure is a key factor in tankless performance, but many buyers ignore it until problems appear. If your home has low water pressure, a tankless water heater may struggle to activate properly or deliver consistent hot water flow.
In many European cities, older buildings have lower water pressure due to aging infrastructure. Apartments on higher floors may also have weaker pressure unless a booster pump is installed.
If your water pressure is too low, the heater may fail to maintain stable heating, especially if multiple taps are open. Some models are designed to operate at lower pressure, but not all.
Before buying, you should check your home’s water pressure level and compare it to the heater’s minimum operating requirement. This is especially important if you live in an older flat or a multi-storey building.
Mistake #6: Not Considering Hard Water and Limescale Buildup
Hard water is extremely common in many European countries, including areas of the United Kingdom, France, Spain, Germany, and Italy. Hard water contains minerals such as calcium and magnesium, which can create limescale buildup inside a tankless water heater.
Limescale reduces efficiency, restricts water flow, and can shorten the lifespan of your heater. It also increases energy consumption because the heating elements or heat exchanger must work harder to reach the desired temperature.
Many homeowners make the mistake of buying a tankless water heater without planning for descaling maintenance. Some assume the heater will remain efficient forever, but in hard water regions, regular cleaning is essential.
To avoid this issue, it is important to consider models that are designed to handle hard water better, and to plan for maintenance such as descaling every 6 to 12 months depending on your water hardness level. Installing a water softener or scale prevention filter may also be a smart long-term investment.
Mistake #7: Choosing the Cheapest Option Without Looking at Long-Term Costs
A low price tag can be tempting, especially when shopping online. Many buyers focus only on upfront cost and ignore the long-term expenses that come with low-quality models.
Cheaper tankless water heaters may have lower efficiency ratings, weaker temperature control, and shorter lifespans. They may also require more frequent repairs or have limited warranty coverage.
In Europe, where energy costs can be high, a poorly performing tankless water heater can increase your monthly electricity or gas bills. Over several years, the extra operating cost can easily exceed the savings from choosing the cheapest model.
The better approach is to look at overall value. A high-quality tankless water heater with strong efficiency and reliable performance may cost more initially, but it can save money over time through reduced energy waste and fewer maintenance issues.
Mistake #8: Ignoring EU Energy Efficiency Ratings and Standards
Europe has strict energy efficiency regulations, and buyers have access to useful rating systems that help compare models. However, many homeowners ignore these labels and choose based only on marketing descriptions.
A tankless water heater should meet EU standards and have clear performance documentation. Choosing a heater without proper certifications can be risky, especially when it comes to safety, warranty, and legal installation requirements.
Some imported models may not meet European compliance standards. Even if they are cheaper, they may not be approved for installation in your region.
To avoid this mistake, you should always check that the tankless water heater is compliant with EU regulations and comes with proper energy efficiency labeling. This ensures better safety, better performance, and fewer installation issues.
Mistake #9: Buying the Wrong Size for Your Home Layout
European homes come in many different layouts, from compact city flats to multi-level countryside homes. A major mistake is buying a tankless water heater without thinking about how far the hot water needs to travel.
If the heater is installed far from the bathroom or kitchen, you may experience a delay before hot water reaches the tap. This results in wasted water and reduced comfort.
Some homeowners assume tankless systems provide instant hot water everywhere, but the truth is that tankless heating is instant only at the heater itself. The distance between the heater and the tap still affects delivery time.
If your home has long pipe runs, you may need a recirculation system or a point-of-use tankless heater near the most frequently used areas. Choosing the wrong setup can lead to frustration, especially in larger European homes with multiple floors.
Mistake #10: Forgetting to Check Noise Levels
Noise is often overlooked when purchasing a tankless water heater. Some models can be louder than expected, especially gas-powered systems with internal fans and burners.
In Europe, where many people live in apartments with thin walls, noise can be a serious concern. A loud heater can be disruptive, particularly if installed near a bedroom or living room.
Before buying, it is smart to check product reviews and specifications for noise levels. Quiet operation is often a sign of better engineering and higher build quality.
Mistake #11: Not Planning for Professional Installation
Many buyers assume a tankless water heater is a simple replacement for a traditional tank system. In reality, installation is often more complex, especially in Europe, where plumbing standards and building regulations vary.
Gas models may require venting work and gas line adjustments. Electric models may require dedicated circuits and electrical upgrades. Even water pipe connections may need modifications depending on your current system.
Trying to install a tankless water heater without professional support can lead to leaks, safety issues, or system failure. It can also void your warranty if the manufacturer requires certified installation.
The best approach is to factor installation costs into your budget and work with a qualified installer who understands local regulations.
Mistake #12: Choosing a Model Without Smart Temperature Control Features
Temperature stability is one of the biggest reasons people upgrade to tankless water heaters. However, not all models offer advanced temperature control.
Some cheaper systems can fluctuate when water flow changes, such as when someone flushes a toilet or uses another tap. This can cause uncomfortable hot and cold shifts during showers.
Many modern tankless water heaters offer digital temperature displays, thermostatic control, and smart settings that improve comfort and safety. These features also help prevent scalding, which is especially important in homes with children or elderly family members.
Buying a heater without stable temperature control is a mistake that can reduce the comfort benefits you expect from a tankless upgrade.
Mistake #13: Ignoring Maintenance Access and Placement
Placement matters more than most buyers expect. Some homeowners choose a location based only on available space, without considering whether the heater will be easy to access for maintenance.
In Europe, many homes have limited utility space, and it can be tempting to install the heater in a tight cupboard or small corner. But tankless systems require periodic servicing, descaling, and inspection.
If the heater is difficult to access, maintenance becomes more expensive and less likely to be done regularly. Over time, this can reduce efficiency and shorten lifespan.
A good installation location should provide enough clearance for servicing, proper airflow if needed, and safe drainage options if the system requires it.
Mistake #14: Forgetting About Warranty and Service Support in Europe
Warranty coverage and after-sales support are critical when buying any heating system. Yet many buyers focus on features and price while ignoring whether replacement parts and service technicians are available in their region.
A tankless water heater is a long-term investment, and repairs may be needed after several years. If the brand does not have strong support in Europe, you may face long delays or expensive repair costs.
Before buying, you should check warranty length, what is covered, and whether the manufacturer has service partners in your country. It is also wise to confirm that spare parts are available locally.
This is one of the most overlooked mistakes and often becomes a major problem only after the heater is installed.
How to Buy the Right Tankless Water Heater in Europe With Confidence
Avoiding mistakes is not only about knowing what not to do. It is also about following a smart buying process.
A confident purchase starts by understanding your household hot water usage, your local climate, and your home’s power or gas supply. It also includes checking installation requirements, water hardness levels, and long-term maintenance needs.
When you take the time to match the heater’s performance to your real-life needs, you greatly reduce the risk of poor comfort, wasted energy, or costly upgrades later.
Tankless water heaters can be an excellent solution for European homes, but only if the system is selected carefully. A well-matched tankless water heater will provide years of comfort, lower energy waste, and reliable hot water whenever you need it.
Final Thoughts: Avoid These Mistakes and Get the Best Tankless Water Heater for Your European Home
Buying a tankless water heater in Europe is not a decision you want to rush. The most common mistakes come from choosing the wrong size, ignoring electrical or gas requirements, underestimating cold climate performance, and failing to plan for hard water maintenance.
European homes have unique challenges, including compact spaces, strict regulations, and varying water pressure levels. When you choose a tankless water heater that fits your household's needs and meets European compliance standards, you protect your investment and enjoy better comfort every day.
By avoiding the mistakes covered in this guide, you can confidently choose the right tankless water heater and enjoy efficient, reliable hot water for years to come.
Frequently Asked Questions
What is the biggest mistake people make when buying a tankless water heater in Europe?
One of the biggest mistakes is choosing a tankless water heater without checking the required flow rate for the household. If the system is too small, it may not supply enough hot water for multiple taps or showers running at the same time.
Are electric tankless water heaters a good choice for European homes?
Electric tankless water heaters can be an excellent choice, especially for apartments and smaller homes. However, homeowners should always check if their electrical system can support the power demand, since some models require upgraded wiring or 3-phase electricity.
Why does my tankless water heater struggle during winter?
This usually happens when the incoming water temperature becomes much colder. A higher temperature rise is required in winter, which can reduce hot water output if the heater is not powerful enough for colder European climates.
Is a gas tankless water heater better than an electric one?
Gas tankless water heaters often provide stronger performance for larger households and colder regions. However, they require proper ventilation, gas line capacity, and compliance with local European installation regulations, which may increase installation costs.
How do I know what size tankless water heater I need?
You should estimate how many hot water outlets might run at the same time, such as showers, kitchen taps, and appliances. The more simultaneous usage your household has, the higher the flow rate capacity you will need.
Does hard water affect tankless water heaters in Europe?
Yes, hard water is common in many parts of Europe and can cause limescale buildup inside the heater. This can reduce efficiency, lower performance, and shorten lifespan if regular descaling maintenance is not done.
How often should a tankless water heater be descaled?
In areas with hard water, descaling is often recommended every 6 to 12 months. In softer water regions, maintenance may be needed less frequently, but regular checks are still important.
Will a tankless water heater give instant hot water?
A tankless water heater heats water instantly, but it does not always deliver hot water immediately at the tap. If your plumbing lines are long, you may still experience a delay while hot water travels through the pipes.
Can I install a tankless water heater myself?
It is not recommended. Most tankless water heaters require professional installation, especially in Europe, where electrical, gas, and plumbing regulations are strict. Improper installation can also void the warranty.
What should I check before buying a tankless water heater in Europe?
You should check your home’s water pressure, electrical capacity or gas connection, climate conditions, water hardness, installation space, and local building regulations. These factors will help ensure you choose a model that performs well and lasts longer.