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VDI 2035 Water Treatment in Heating Systems

Water treatment is a critical aspect of maintaining the efficiency and longevity of heating systems. In the field of water treatment, one widely recognized standard is VDI 2035. This comprehensive guide explores the importance of implementing VDI 2035 water treatment guidelines in heating systems, focusing on optimizing performance, preventing corrosion, and extending the system's lifespan.

Heating systems play a crucial role in various industries. However, they can be vulnerable to issues such as scale formation, corrosion, and impaired performance if proper water treatment measures are not taken. In this post, we will delve into VDI 2035 water treatment guidelines and how they can contribute to the efficient functioning of heating systems.

Understanding VDI 2035 Water Treatment

VDI 2035 is a German guideline that sets recommendations and requirements for water treatment in heating systems. It emphasizes the prevention of harmful substances such as scale and corrosion, which can impede heat transfer and reduce system performance. To comply with VDI 2035, several key requirements need to be addressed.

Water Hardness

Water hardness is a significant factor affecting heating system efficiency. VDI 2035 introduces the concept of the "water hardness index" and provides specific concentration limits for calcium and magnesium ions, the primary contributors to water hardness. By controlling water hardness, the formation of limescale can be greatly reduced.

Feed Water Quality

The quality of the water that enters the heating system is critical. Impurities such as suspended solids and dissolved gases can cause damage and reduce system performance. VDI 2035 recommends specific measures to remove these impurities and ensure clean feed water.

Corrosion Protection

Corrosion can cause substantial damage to heating systems, compromising their efficiency and leading to premature failure. VDI 2035 provides recommendations for selecting suitable corrosion protection methods, including the use of demineralised product water and adjusting water chemistry through pH modification.

Scale Prevention

Scale formation due to mineral deposits can significantly impact the heat transfer efficiency of heating systems. VDI 2035 guides users on scale prevention techniques, including physical water treatment methods (e.g., magnetic or electronic descalers) to minimize scale formation and maintain system performance.

Implementing VDI 2035 Water Treatment

To effectively implement VDI 2035 water treatment guidelines in heating systems, certain best practices should be followed.

Regular Water Analysis

Regular water analysis is essential to determine the water hardness, identify impurities, and assess the overall water quality. This analysis provides crucial data to determine the appropriate treatment methods required for the specific heating system.

Selection of Treatment Methods

Based on the water analysis results, suitable treatment methods can be selected. Factors such as the type of heating system, water quality, and environmental considerations should be taken into account. Proper treatment methods include filtration and physical water treatment solutions.

Maintenance Schedules and Tasks

Regular maintenance is crucial to ensure the continuous effectiveness of water treatment in heating systems. This includes monitoring water quality, maintaining the right ph balance, and cleaning or replacing filters and equipment as needed. Adhering to VDI 2035 guidelines ensures that system maintenance aligns with industry best practices.

Compliance with VDI 2035 Guidelines

To achieve the full benefits of VDI 2035 water treatment, it is important to comply with the specific requirements outlined in the guideline. Regularly reviewing and updating practices to stay in line with any updates or revisions enhances the efficiency and longevity of heating systems.

Benefits of VDI 2035 Water Treatment

Implementing VDI 2035 water treatment guidelines offers several benefits for heating systems.

1. Enhanced System Efficiency and Performance
Proper water treatment improves heat transfer efficiency by preventing scale formation and reducing corrosive activity. This leads to optimal performance levels, lower energy consumption, and improved overall system efficiency.

2. Prolonged Lifespan of Equipment
By preventing scale deposition and corrosion, VDI 2035 water treatment helps to extend the lifespan of heating system components, reducing the frequency of repairs and replacements. This results in cost savings and improved system reliability.

3. Cost Savings
Efficient water treatment minimizes the need for system maintenance, repairs, and premature replacements. This reduces operational costs and ensures long-term cost savings for heating system owners.

To ensure optimal performance and minimize the risk of corrosion and system failures, specific water parameters need to be controlled. Here are the important water parameters outlined in VDI 2035:

  • Hydrogen pH: The recommended pH range is 8.2-10. Maintaining pH levels within this range helps mitigate corrosion. If aluminum is present, pH should ideally not exceed 8.5. 

  • Chloride (Cl) Content: The chloride concentration should be limited to 10 mg/l. Excessive chloride levels can contribute to corrosion-related issues.

  • Copper (Cu) Content: The copper concentration should be kept below 0.02 mg/l. Exceeding this level can lead to component failures and system breakdowns.

  • Iron (Fe) Content: The iron concentration should not exceed 0.1 mg/l. Higher iron levels can accelerate corrosion processes.

  • Dissolved Oxygen: The recommended dissolved oxygen level is 0.1 mg/l. Managing oxygen ingress is crucial to prevent corrosion and subsequent damage to system components.

  • Total Hardness: The ideal range for total hardness is 10-200 mg/l. Monitoring and controlling hardness levels contribute to system longevity and performance.

  • Conductivity: The recommended conductivity range is 50-100 μS/cm. Lower conductivity helps restrict corrosion reactions and maintain water quality.

These parameters are designed to ensure that the water used in heating and cooling systems is free from impurities that can cause corrosion. By controlling these parameters, operators can reduce the risk of equipment damage and improve system efficiency and longevity.

Importance of Chemical-Free Methodology

The non-additive approach to chemical water treatment, as advocated by VDI 2035 and similar standards, has gained significant traction. Utilizing high-quality resin cartridges helps lower water conductivity and set the pH to appropriate levels. This, in turn, minimizes the possibility of corrosion, even in the presence of oxygen. Furthermore, pH-related corrosion, often overlooked, can be effectively addressed through fill cartridges that adhere to VDI specifications.

Enhanced Protection with Electrochemistry Units

To provide an additional layer of protection, electrochemistry units can be employed. These units maintain pH levels and low conductivity while removing limescale deposits, sludge, and gases. They act as micro gas separators by eliminating oxygen and other gases from the circulating water, thus further safeguarding against corrosion. Magnetic flow filters integrated into these units aid in removing debris and corrosion particles, ensuring optimal water quality and pH maintenance.

There are various options available for water conditioning in accordance with VDI Directive 2035, including filling units and accessories. Thoroughflush, a reputable source, offers a range of products for water treatment and central heating system cleaning. One example is the VDI2035 MOBILE FILLING UNIT VA14 demineralization unit, which utilizes a special ion exchange resin mixture to desalinate heating filling and supplementary water. Specifically designed for filling water in heating systems while adhering to the guidelines of VDI Directive 2035. Thoroughflush's website provides detailed information about this unit and other products aimed at achieving water conditioning and system cleanliness.

Additionally, the CLARIMAX 1200 DM pH+ LED is another option compliant with VDI2035 fill methods. This cartridge-based system eliminates the need for resin handling and ensures low conductivity and alkaline pH. Integrated measurement technology allows for real-time monitoring of water quality. 


Elector Purofill - VDI2035 MOBILE FILLING UNIT VA14. 

Clarimax - 1200 DM pH+ LED (VDI2035)

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