The principle of heat recovery

In today’s world, where energy efficiency and sustainability are becoming increasingly important, heat recovery systems are a crucial element in modern ventilation technologies. Especially in decentralized ventilation systems, heat recovery ensures that energy is not lost but is used sensibly to reduce heating costs and optimize the indoor climate.

Systems with heat recovery are not only energy-saving, but also environmentally friendly. They reduce energy consumption and at the same time improve the CO₂ footprint of a building. An example: A ventilation unit with an energy consumption of only 1 kW can recover up to 20 kW of heating energy – a clear advantage for sustainable construction.

Why is residential ventilation so important?

1. Protection of the building fabric: Moisture produced by breathing, cooking, or showering can lead to mold growth if ventilation is inadequate. Intermittent ventilation is often not enough to reduce moisture in the long term.
2. Health benefits: Ventilating by opening windows often brings noise, pollen, and pollutants into the house. However, with the windows closed, odors and vapors accumulate, which can lead to respiratory diseases.
3. Sustainability and comfort: Ventilation systems provide controlled ventilation and prevent energy loss through open windows.

What is heat recovery and why is it important?

Heat recovery refers to the process of transferring heat from the exhaust air of a room to the fresh air that is fed into the room. This takes place in a heat exchanger, which acts as the heart of the system. The aim is to use the heat contained in the air instead of allowing it to escape unused. This reduces energy consumption, as less heating energy is required to bring the room to the desired temperature.

In conventional ventilation systems, a large part of the heat energy is lost with the exhaust air, which then has to be recovered through additional heating. Heat recovery makes it possible to recover and reuse this heat energy, resulting in significant energy savings. Especially in times of rising energy prices and increased environmental awareness, heat recovery is an important step toward more sustainable construction and living.

It is important for installers to understand that heat recovery not only helps to reduce heating costs, but also significantly improves the indoor climate. In times of energy crises and rising heating costs, the efficient use of ventilation technology with heat recovery is a central component of modern building equipment. Those working in this field must be familiar with the different systems and how they work in order to find the best solutions for customers.

The advantages of heat recovery

Efficient ventilation is essential in modern new buildings and renovated buildings, as these structures are particularly airtight. Inadequate ventilation can not only reduce air quality, but also endanger the building fabric. In this article, you will learn why ventilation systems with heat recovery are a sustainable choice and which system types are suitable for different requirements.

Ventilation systems with heat recovery (HR) are not only efficient, but also environmentally friendly. Here are three compelling reasons:

• Energy savings: HR can reduce ventilation heat losses by up to 85%, thereby lowering heating requirements by around 40%. This means that the heating system can be smaller, saving costs.
• Sustainability: Recycling heat energy minimizes the carbon footprint.
• Long-term cost savings: The investment in HR systems pays for itself through reduced operating costs.

Influence of air flow rate and temperature difference on efficiency

The air flow rate and the temperature difference between fresh air and exhaust air are the two decisive parameters for the efficiency of a heat recovery system. The greater the temperature difference, the more heat can be transferred. It is therefore important to set the correct air flow rate to ensure maximum system efficiency. Insufficient air volumes lead to inadequate heat transfer, while excessive air volumes can unnecessarily increase energy consumption.

When selecting the right heat exchanger, it is important to pay attention to its dimensions and efficiency. An optimally dimensioned heat exchanger can significantly increase the energy efficiency of the ventilation system and thus reduce the building’s energy consumption. In addition, factors such as materials, maintenance requirements, and service life also play a decisive role in the selection of a suitable heat exchanger.

The heat exchanger in a ventilation system is therefore an essential component that helps to improve the comfort and energy efficiency of a building.

Heat recovery in decentralized ventilation systems: Technical requirements and solutions

The technical requirements for decentralized ventilation systems with heat recovery include air volume flows, heat exchanger efficiency, sound insulation, and control options. It is crucial that the systems are highly efficient in order to reduce energy consumption and ensure sustainable ventilation. Modern decentralized ventilation systems offer innovative solutions to meet these requirements. The integration of highly efficient heat exchangers that enable efficient heat recovery is a key factor. In addition, quiet fans and optimally coordinated controls are essential to ensure the comfort of residents.

Functionality in decentralized systems

In decentralized ventilation systems, heat recovery is installed directly in each room or area, which has the advantage of not requiring central duct systems. These systems are particularly suitable for smaller buildings or apartments, as they offer a flexible and cost-effective solution without the need for major renovation work.

Decentralized systems make it possible to control the air volume and temperature individually for each room, which further increases efficiency. For tradespeople, this means that they can dimension and install the systems precisely for each project.

Compatibility with existing systems

In existing buildings in particular, the question often arises as to how heat recovery systems can be integrated into existing ventilation systems. Tradespeople must ensure that the new systems are compatible with the existing heating systems and ventilation ducts without impairing the operation of the existing systems. This often requires precise planning and possibly the adaptation of the air flow and system technology.

Combined ventilation systems – the right solution for every scenario

Combined ventilation systems combine different technologies to cater to all areas of a building. Here is an overview of the main approaches:

1. Separate ventilation areas: Children’s rooms and bedrooms are equipped with decentralized supply/exhaust air units, while free ventilation is used in living rooms and wet rooms. Components such as outside air vents (ALD) and overflow air vents (ÜLD) enable targeted air flow.
2. Overlapping ventilation areas: In rooms such as windowless bathrooms, ventilation systems in accordance with DIN 18017-3 are combined with free ventilation. This solution optimizes air exchange with minimal energy consumption.
3. Hybrid ventilation: Main systems such as shaft ventilation are supplemented by secondary systems (e.g., exhaust fans). These systems respond flexibly to changing requirements, such as those that occur during the transition period.

System optimization and fault diagnosis

System optimization of heat recovery systems is a crucial step in maximizing their efficiency and performance. Regular maintenance and fault diagnosis allow potential problems to be identified and rectified at an early stage.

Identifying sources of error

Even the best heat recovery system can become inefficient for a variety of reasons. Possible problems include clogged filters, insufficient air flow, or defective heat exchangers. In such cases, it is of course important to diagnose errors quickly and take targeted measures to remedy them. It is particularly important to check the air flow regularly to ensure that the heat exchanger is working efficiently. When diagnosing faults, it is crucial to identify potential problems such as leaks, contamination, or mechanical damage. Seek assistance from experts who have the necessary know-how and experience to make an accurate diagnosis. Systematic fault diagnosis enables targeted measures to be taken to optimize the system. This includes cleaning filters, checking pipes for leaks, and calibrating sensors.

Optimization tips

Regular air exchange and adjustment of air volumes are essential for long-term good performance of the system. The use of intelligent controls that automatically adjust the air flow to the respective conditions can also help to increase efficiency.

An important aspect of system optimization is checking the air flow and the heat exchanger. Inadequate air circulation can impair the efficiency of heat recovery. It is therefore important to ensure that all components are functioning properly and are correctly dimensioned.

By regularly performing system optimizations and fault diagnostics, you can ensure that your heat recovery system is functioning optimally and that energy efficiency is guaranteed.

Planning and balancing according to DIN standards

All systems must be planned and designed in accordance with DIN 1946-6 to ensure optimum efficiency and functionality. Balancing is carried out in accordance with DIN V 18599-6, taking into account different ventilation areas in proportion to their surface area.

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Heat recovery is an efficient way to save energy and protect the environment. By using heat exchangers in ventilation systems, the heat from the exhaust air is used to warm the fresh supply air without wasting energy. Technical fundamentals such as the heat exchanger and optimal system integration are crucial for the effectiveness of heat recovery. Installers play an important role in the professional installation and optimization of these systems in order to maximize their performance. Through careful system optimization and regular fault diagnosis, heat recovery can be continuously improved to offer customers innovative solutions that are both environmentally and economically beneficial.