Importance and necessity of hydraulic balancing and why there are two methods (A and B)

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Since 2023, there has been an important change in the area of heating technology in Germany: Hydraulic balancing in accordance with method B is now mandatory for all new and modernized heating systems.

Anyone who has ever lived in a house with heating problems — rooms that are too hot or too cold, loudly noisy radiators — knows how important it is that a heating system is optimally adjusted. The solution to such problems is often a correctly performed hydraulic adjustment. Hydraulic balancing ensures that all rooms in a building are heated evenly and efficiently. It not only optimizes the indoor climate, but also saves energy and therefore costs.

Hydraulic balancing ensures that the heating system works optimally. The goal: Each room receives exactly the heat it needs. This not only improves wellbeing, but also contributes to energy savings of up to 15-20%. But what is hydraulic balancing in detail and why are there different methods for carrying it out?

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Basics of hydraulic balancing: What does hydraulic balancing mean?

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Hydraulic balancing

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Hydraulic balancing is an essential process for optimising heating systems. In this process, the actual amount of heat required for each room is determined, taking into account factors such as the energy quality of the building, the condition of the windows and the insulation of the outer walls. Based on this data, the required amount of heating water and the correct pump output are then calculated. The aim is to maximize the efficiency of the heating system, reduce energy consumption, reduce heating costs and extend the life of the system.

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Heating system and heating surface optimization

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A heating system basically consists of a heating source, distribution lines, control technology and heating surfaces. These heating surfaces, such as radiators or floor heating systems, are responsible for transmitting the generated heat to the rooms. An optimized heating surface is essential to ensure uniform and demand-oriented heat distribution. Without hydraulic balancing, heating surfaces can be oversupplied or undersupplied, which impairs living comfort and increases energy consumption. Adapting the heating fluid flow rate to the individual requirements of each room plays a central role in optimising the efficiency of the entire system.

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Flow temperature and return temperature

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The flow temperature is the temperature of the heating water when it is directed from the heating source (e.g. heat pump or boiler) to the radiators, floor heating systems or other heating surfaces in the building. It is largely responsible for how much heat is emitted to the rooms. The higher the flow temperature, the more heat is released into the room. After the heating water has transferred heat to the rooms, it flows back to the heating source — now at a lower temperature. This temperature is known as the return temperature. A lower difference between flow and return temperature indicates efficient heat transfer and therefore a well-adjusted heating system. Conversely, a large temperature difference can indicate inefficiency and potential need for optimization.

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example: Imagine a building in which the heating system is designed for a room temperature of 20-22°C. There are two different types of heating surfaces in this building: small radiators and floor heating.

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• small radiators: Due to their small size, these types of heating surfaces have a smaller surface area to transfer heat to the room. A higher flow temperature is therefore required to achieve the desired room temperature. This can cause the heating system to use more energy to generate and maintain the higher temperature. For example, a flow temperature of around 60-70° C. could be necessary here.
• floor heating: In contrast, floor heating has a larger surface area for heat transfer, as the entire floor area of the room is used. This makes it possible to achieve the desired room temperature with a significantly lower flow temperature. In this case, a flow temperature of 35°C could be sufficient.

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Differences between procedures A and B: How do procedures A and B differ in detail?

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The method A

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Method A of hydraulic balancing is a simplified method which is primarily designed for smaller and less complex heating systems, as are common in single-family homes or small apartment buildings. In this process, standardized values and empirical values (tabular values) are used. The heating load is determined on the basis of room size and room type, the valve settings regulate the volume flow of the heating water on the basis of standardized values, and the output of the circulation pump is often adjusted to the determined heat load using standard values.

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The method B

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Method B, the focus of this article, is a more detailed and precise method for hydraulic balancing. It takes into account the individual characteristics of each room, such as size, thermal insulation, window areas and external conditions. Through precise calculations and measurements, the required heating load for each room is determined in order to achieve the optimal adjustment of valves and pump output. This process is particularly suitable for larger and more complex heating systems and can significantly contribute to energy savings.

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Historical context: Until 31.12.2022, method A was mainly used for hydraulic adjustments. As a rule, the heating systems here were oversized simply to be on the safe side because the cost differences were too low. In the case of heat pumps in particular, however, oversizing not only leads to significant purchase costs, but also to increased operating costs (see Blog article about oversizing WP). Over time, awareness of energy efficiency and technology has therefore evolved, so that more accurate and individual solutions such as method B have been required to meet the various requirements and conditions of buildings.

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Process and duty: Hydraulic balancing is not only useful for optimising heating systems, but is also required by law for certain renovations or new installations. The aim is to reduce energy consumption and CO2 emissions in order to significantly reduce environmental impact.

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Technical aspects of process B: What are the key technical points of process B?

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The precise calculation of building and room heating loads is a central element of method B. Here, the building heating load indicates how much energy is required in total to heat the entire building, while the room heating load specifically takes into account the energy requirements of each individual room.

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A building suffers heat losses through transmission and ventilation — this means that heat escapes both through the building envelope, consisting of walls, ceilings, windows, etc., and through air circulation. In order to ensure an efficient heat supply and compensate for these losses, the settings of valves, pump output and flow temperature must be optimally coordinated with the calculated heat load.

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• U value (heat transfer coefficient): The U-value quantifies the heat losses of an area of 1m² with a temperature difference of 1°C and is given, for example, by the Federal Ministry of the Interior, Building and Community for the respective construction age group. The exact values can be found in the Federal Gazette. https://www.bundesanzeiger.de/pub/publication/qzQUGd8A3unSCCbVMcf?0.
• Ventilation heat losses: These are calculated based on the specific heat capacity for 1m³ of air, which corresponds to approximately 0.34 Wh/m³*K (DIN 4108-6). The circulation of air and ventilation results in losses that occur independently of the building insulation.
• Standard outdoor temperature: This refers to the lowest temperature that has fallen below at least 10 times in the last 20 years. For Germany, this average temperature is -11.5°C, which must be taken into account when calculating the heating load. However, it differs depending on the exact location and must be adjusted accordingly.
• Pipeline network calculation, pressure loss calculation and volume flows:
• The pipe network calculation makes it possible to size the pipes so that they meet the specific requirements of the heating system. It takes into account various factors such as pipe diameter, pipe length, material properties and thermal conductivity to ensure that heating water can circulate efficiently through the system.
  
  In parallel, the pressure loss calculation is carried out. This calculation is essential to quantify the pressure drop in the heating system. Pressure loss in pipes is influenced by factors such as friction, flow resistance and differences in height. An optimized pressure loss ensures that the circulation pump does not have to be oversized unnecessarily, which in turn saves energy.
  
  A correctly calculated flow rate is the result of these two calculations and is of central importance. It indicates how much heating water flows through the system per unit of time. Optimizing the flow rate ensures that every radiator in the system receives the right amount of heating water.

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DIN 12831

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This is a central standard in the area of hydraulic balancing and heat load calculation. It defines the requirements and methods for determining the standard heat load of buildings. In the context of method B, this standard provides a sound basis for calculating the heat load and helps to ensure that hydraulic balancing is carried out in accordance with uniform and recognized standards.

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An important part of DIN 12831 is the coating process. This method aims to precisely calculate the heat losses of a building through its shell, i.e. walls, ceiling, windows, etc. The entire surface area of the building envelope is taken into account in order to determine the heat transfer losses. Factors such as the insulation of the outer walls, the condition of the windows and the type of construction play a central role.

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Other relevant technical terms

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• circuit control valves: These valves regulate the flow of heating water through the various lines of a heating system and play an important role in optimising hydraulic balancing.
• single-pipe heating: With this system, the heating water circulates successively through all radiators, which places particular demands on hydraulic balancing.
• Night subsidence: Lowering the room temperature during the night can result in energy savings, but must be taken into account as part of hydraulic balancing to avoid loss of comfort.
• differential pressure regulator: These devices keep the pressure in the heating system constant and help maintain hydraulic balance even with fluctuating loads.

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Funding opportunities and legal framework: How do you benefit from hydraulic balancing?

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The state supports hydraulic balancing due to the energy-efficient optimization of heating systems. Oversizing the systems, as in the more inaccurate method A, is not welcome; the state therefore requires a detailed calculation of the heating load and promotes measures that lead to more efficient use of energy.

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KfW (Kreditanstalt für Wiederaufbau), BAFA (Federal Office of Economics and Export Control) and BEG (Federal Funding for Efficient Buildings) are various programs and institutions that offer funding in Germany. Here are the key differences:

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KfW (Kreditanstalt für Wiederaufbau)

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• Institution: promotional bank.
• Type of funding: Offers low-interest loans and grants.
• Objective: Supports various projects, particularly in the areas of construction, housing, energy saving and renewable energy.
• application: Comprehensive funding programs for renovations, new buildings, energy measures, etc.

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KfW offers targeted funding, such as the KfW heating package, to reduce the costs of hydraulic balancing and further optimization measures. Both grants and low-interest loans can be used to improve the efficiency of the measures.

https://www.handelsblatt.com/politik/kfw-foerderprogramm-kfw-effizienzhaus-foerderung-koennte-erneut-gestoppt-werden/28381038.html

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BAFA (Federal Office of Economics and Export Control)

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• Institution: Federal agency.
• Type of funding: Offers primarily direct subsidies.
• Objective: Focus on energy, efficiency and technology, in particular heating optimization and renewable energy.
• application: Funding for the installation of efficient heating systems, use of renewable energies and energy consulting.

BAFA heating optimization focuses on measures such as hydraulic balancing, which contribute to improved efficiency of heating systems. Funding of up to 15% is possible here. https://www.energiewechsel.de/KAENEF/Redaktion/DE/Foerderprogramme/heizungsoptimierung.html

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BEG (Federal Funding for Efficient Buildings)

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• Institution: Funding program organized by BAFA and KfW.
• Type of funding: Offers grants and loans for energy measures.
• Objective: Increasing energy efficiency and using renewable energy in buildings.
• application: Support for energy-efficient renovations and new buildings, individual measures or comprehensive renovation to a KfW efficiency house.

BEG funding (federal funding for efficient buildings), on the other hand, covers a wider range of measures to increase energy efficiency and use of renewable energy. The funding rates are up to 40% for heat pumps, taking into account the heating exchange bonus and heat pump bonus (as of 15.08.2022). Specialist planning and construction support is subsidized with up to 50%; the possible maximum amount per individual measure depends on the specific measure. https://www.bafa.de/SharedDocs/Kurzmeldungen/DE/Energie/Effiziente_Gebaeude/20220821_anpassung_beg.html

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Also important: The Building Energy Act 2024 (GEG)

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The Building Energy Act (GEG) 2024 is significantly relevant for method B and heating systems. It defines the energy requirements for new and existing buildings and thus sets the legal framework for energy-related renovation measures. The implementation of hydraulic balancing can help to meet the GEG requirements.

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Also relevant for you: The new Heating Act/Building Energy Act 2024

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Practical implementation and tools: What is the best way to achieve hydraulic balancing?

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Proof of hydraulic adjustment

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Hydraulic balancing not only optimizes the heating system, but is often also a prerequisite for government subsidies. Evidence of hydraulic balancing is therefore essential. The VDZ form — a standardized form from the Association of the German Heating Industry — offers a structured way to document all relevant data and settings and thus serves as recognized proof that the hydraulic adjustment has been carried out. https://www.vdzev.de/service/formulare-hydraulischer-abgleich/

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Do it yourself or an expert?

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While it is entirely possible to perform some aspects of hydraulic balancing yourself, particularly with simpler heating systems, expertise and experience are essential to achieve optimal results. For more complex systems and when using method B, it is therefore advisable to consult a specialist or energy consultant. Experts have the necessary equipment, software and experience to perform the adjustment precisely and thus maximize energy savings and operational safety.

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Software support

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Nowadays, there are various software solutions that can significantly simplify hydraulic balancing. Based on the entered data, these programs calculate the optimal settings for valves and pumps and thus make it easier to implement the adjustment.

Software solutions such as those from autarc offer significant support and simplification for hydraulic balancing. It features a range of features that significantly simplify the entire process from project planning to installation.

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• Standard-compliant recording of heating load, heating surfaces and hydraulic balancing Method B: The app enables experts and amateurs alike to record the heating load, heating surfaces and hydraulic adjustment room by room and in accordance with the standard. This automation of the process significantly speeds up data calculation and discussion on site, which is also an advantage when pre-selecting a suitable heat pump.
• Comprehensive documentation: The software provides an integrated solution for creating all legally required calculations and documentation. Comprehensive documentation is particularly relevant when applying for funding and supports experts in providing comprehensive advice to their customers.
• Quick eligibility check: With an integrated database and an intelligent query system, autarc enables rapid verification of the eligibility of a project as part of BAFA's Federal Funding for Efficient Buildings (BEG).
• Direct application for funding: It is also possible to apply for funding directly as soon as the eligibility of a project has been determined. This significantly simplifies and speeds up the process and minimizes the risk of errors that could occur when submitting a manual application.

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Conclusion

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Hydraulic balancing is a crucial process for optimising the efficiency of heating systems. It ensures uniform heat distribution, reduces energy losses and thus contributes to significant cost savings. At a time when sustainability and energy efficiency are the focus, this is of immense importance.

The implementation of hydraulic balancing is supported by numerous funding opportunities and legal regulations. Both BAFA and KfW funding provide financial support and facilitate the implementation of energy-efficient measures. This support underlines the importance of optimising heating systems for environmental protection and the energy revolution.

The decision whether to carry out the hydraulic adjustment yourself or hire an expert depends on individual circumstances and knowledge. While some aspects can certainly be implemented on your own, the expertise of a specialist can be an advantage for more complex systems and specific requirements. Professional implementation ensures compliance with standards and maximizes efficiency gains.

Thanks to technological advances, there are now a variety of tools and software solutions, such as those from autarc, which significantly simplify hydraulic balancing. These digital tools help to minimize errors, optimize processes and thus contribute to more effective and precise implementation.

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Try autarc for yourself!

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Would you like to optimize the efficiency of your heating system and benefit from the benefits of hydraulic balancing? Then it's time to try out autarc for yourself! With our innovative software, you can make the entire process simple and precise, from planning to implementation. Whether you're a specialist or a layman, autarc's user-friendly interface and diverse functions provide you with the support you need.

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Record heating load, heating surfaces in accordance with standards and carry out hydraulic balancing procedure B, check the eligibility of your project and apply for funding directly from the app! Take the first step towards a more energy-efficient home and see how autarc makes the difference.

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click here to find out more about autarc and get started right away.