Functionality of instantaneous water heaters

Intro

Instantaneous water heater

Heat on demand: Your direct way to save.

With an instantaneous water heater, you can enjoy hot water exactly when and where you need it. Whether specifically for rooms such as your kitchen, bathroom or even your entire home. We will guide you through the different types of instantaneous water heaters, explain what is important and help you to find the perfect domestic hot water solution for your needs.

Functionality of instantaneous water heaters

Operating principle of instantaneous water heaters

Hot water exactly when you need it.

An instantaneous water heater effortlessly delivers hot water to your tap the moment you need it. Cold water flows through the unit and is rapidly heated to your desired temperature. You can choose from efficient gas or electric models, both featuring a high-performance heat exchanger at the core of their design.

Gas-powered instantaneous water heater utilize finned tubes positioned above the burner to quickly heat the water as it passes through. Electric instantaneous water heaters employ a powerful heating block that instantly raises the water temperature.

Good to know:Instantaneous water heater are sometimes mistakenly called "boilers." A boiler generates steam under high pressure, providing a constant supply of hot water. An instantaneous water heater only heats cold water to the required temperature on demand.

Advantages of instantaneous water heaters

Small, but powerful.

Direct desired temperature.
Instantaneous water heaters heat the water to exactly the temperature you want without waiting.
Highly efficient.
Instantaneous water heaters don't waste energy on storing hot water. It also avoids heat losses caused by standing water in boilers.
Low acquistition costs.
In addition to the low operating costs, which are only incurred when using the instantaneous water heater, there is also no need to purchase a hot water storage tank.
Very hygienic.
As the water is only heated when required, stagnant water and legionella formation are avoided. In addition, there is no hot water tank in which germs could multiply.

Different use cases

The right instantaneous water heater for every need.

Electric instantaneous water heaters are particularly effective when it comes to heating water quickly and reliably. They offer the advantage of not requiring any special connections or exhaust systems, and maintenance costs are minimal compared to other options.

Bathroom
Kitchen
Guest restroom

The bathroom typically requires more hot water than other areas, due to activities like showering and bathing. It's essential to select an electric instantaneous water heater with enough capacity to meet these needs. Our models electronicVED exclusive and electronicVED, are especially suited for this purpose.

In the kitchen, hot water demand is typically lower than in the bathroom, mainly needed for dishwashing and occasional cooking. A smaller, less powerful under sink electric water heater, like the electronicVED with adjustable temperature, is sufficient.

For occasional hot water needs at the kitchen sink, an electric small storage unit is a viable alternative. Our eloSTOR 5-liter under-sink model can heat water up to 85°C ans store it making it availabe just when you need it for dishwashing and quick rinsing of kitchen appliances.

What do hot water and installers have in common? You don't wait long for either of them.

Get in contact with local partner

Types of instantaneous water heaters.

Hydraulic, electric and fully electric water heaters.

Instantaneous water heaters can be divided into two categories: hydraulic and electronic/fully electronic units. Hydraulic technology is older and rarely produced today, as it heats water in large steps and consumes a lot of energy. Modern units are electronic, measuring water temperature for much more precise and efficient operation.

Electronic instantaneous water heaters.
An electronic instantaneous water heater measures the incoming water temperature and flow rate. Using a predefined heating curve, it precisely controls the water temperature, right up to the unit's maximum output.
Fully electronic instantaneous hot water heaters.
Fully electronic instantaneous water heaters offer even more precise temperature control by measuring outgoing water temperature and adjusting output instantly. This closed-loop system ensures water is always at your desired temperature, accurate to within a degree. Even with high flow rates, integrated flow control maintains consistency, reducing volume if needed.
Hydraulic instantaneous water heaters.
Hydraulic instantaneous water heaters offer staged heating based on water pressure, accommodating varying hot water needs. However, they may experience temperature changes when multiple taps are in use, requiring careful management to optimise efficiency in water and energy use.

Instantaneous water heater or hot water cylinder?

Heating efficiently starts with the right choice.

Instantaneous water heater or hot water storage tank? That's the question many homeowners face. Choosing the right system for your hot water needs, centralized with a tank or decentralized with an instantaneous heater, is a key decision. Understanding the differences between these two approaches is crucial for creating the perfect comfort in your home.

	Instantaneous Water Heater	Hot Water Tank/Cylinder
Supply Type	Decentralised	Centralised
Energy Source	Gas, Electricity	Operated by heating system
Operation	Only when needed	Always in operation
Number of Taps (usable simultaneously)	One or more	Multiple or all
Space Requirement	Low	Medium to high
Cost-effectiveness with high water demand	Low	High
Low water demand	High	Low
Purchase Costs	Low to mid-range	Mid-range to high
Compatible with renewable energies	In cold months, reheating of pre-heated water from a solar storage tank is possible	Yes
Hot water output for shower/bath	Low to medium	High

Vaillant tip: instantaneous vs. storage tanks—choose the perfect water heater for your needs.

Modern instantaneous water heaters cut renovation costs in older homes and free up space compared to bulky storage tanks. New builds often meet energy standards, making them perfect for low-temperature systems with storage tanks.

Instantaneous heaters are ideal for occasional hot water use, while storage tanks offer comfort and efficiency for larger households with regular needs.

Frequently asked questions

Still have questions? We have the answers.

Is it possible to mount an instantaneous hot water heater myself?

Installing an electric instantaneous water heater yourself is generally not recommended unless you have experience with both plumbing and electrical work. These installations can be complex and require knowledge of local building codes and safety standards. Additionally, improper installation can lead to safety hazards, such as electrical shocks or water leaks. Many areas require a licensed professional to perform electrical work, and hiring a professional ensures the installation is safe, compliant, and may preserve the warranty. We strongly advise to contact a professional for support.

Get expert consultation

What's the difference between central and decentral hot water supply?

A central hot water system with an efficient instantaneous water heater and storage tank ensures reliable hot water supply to all taps in your home. With a circulation system, enjoy immediate access to warm water as it keeps water moving and heated. Maintaining water at a minimum of 60°C safeguards hygiene by preventing bacteria like Legionella. Even in larger buildings, this system optimises heat retention for consistent warmth.

In a decentralised hot water system, each tap has its own hot water supply via an instantaneous water heater or small storage tank. Our heaters provide hot water on demand, eliminating the need for extensive piping and circulation systems. Modern heaters deliver water at your desired temperature, enhancing efficiency by removing the need to mix hot and cold water. Compact storage tanks offer immediate hot water with minimal standby heat loss, maintaining your preferred temperature.

How much does a 10-minute shower with an instantaneous water heater cost?

The cost of a 10-minute shower using an instantaneous water heater depends on several factors, including the power rating of the heater, the temperature setting, and local electricity rates. Generally, instantaneous water heaters have power ratings between 12 kW and 24 kW.

Let's assume:

Power rating of the heater: 18 kW
Duration: 10 minutes (which is 10/60 hours)
Local electricity rate: €0.20 per kWh (for example)

Calculation:

Energy used: 18 kW x (10/60) hours = 3 kWh
Cost: 3 kWh x €0.20 = €0.60

So, a 10-minute shower could cost approximately €0.60, depending on your specific electricity rate and heater power rating. Adjust the numbers accordingly to your situation.

What is the downside of an instant hot water heater?

Dive deeper into efficient heating.

Hot water storage in front of wall in utility room

Woman in front of electric boiler in kitchen

Instantaneous water heaters: instant hot water, endless comfort.