VDI 2035: Why the Chemical-Free Approach to Water Treatment is Gaining Ground in the UK
VDI 2035: Why the Chemical-Free Approach to Water Treatment is Gaining Ground in the UK
If you’ve never heard of VDI 2035, now’s the time to pay attention. It could change how we protect heating systems from corrosion - without relying on chemicals.
As the UK embraces low-carbon technologies and more efficient heating solutions, attention is shifting toward maintenance practices that are cleaner, simpler, and more sustainable. One such practice gaining serious ground is VDI 2035, a water treatment standard developed by the Association of German Engineers. Unlike traditional UK approaches that rely heavily on chemical dosing and regular inhibitor testing, VDI 2035 offers a preventative strategy by conditioning the water itself.
What is VDI 2035 and why are more UK engineers switching to chemical-free water treatment?
If you're researching how to prevent corrosion in modern heating systems — especially those using heat pumps or heat networks — you've likely come across VDI 2035. This German standard is quickly gaining traction in the UK as a non-chemical, sustainable method for water treatment in sealed systems.
VDI 2035 is a standard that aims to prevent corrosion in closed-loop heating systems by controlling the properties of the fill water - namely its electrical conductivity and pH level.
Rather than neutralising corrosion after it starts, VDI 2035 stops the process at its root. By lowering conductivity and adjusting pH, the water becomes a poor medium for electrochemical reactions, effectively halting corrosion before it can begin. This represents a shift from reactive to proactive system protection.
How do the non-chemical water treatment methods in VDI 2035 work?
The core principle is simple: remove the minerals and salts from the water that enable corrosion to take place. This is typically achieved by passing the system fill water through a resin-based deionisation cartridge, which strips out ions like calcium, magnesium, and chlorides.
Once conditioned, this ultra-pure water is introduced into the heating system. As long as the system remains sealed and uncontaminated by raw water, it can operate for years with minimal degradation. In larger or more complex systems, continuous monitoring or reconditioning units ensure stability over time.
What are the benefits of using VDI 2035 in the UK?
One of the biggest advantages of VDI 2035 is simplified maintenance. With no chemical inhibitors to monitor or replace, the focus shifts to straightforward, user-friendly checks:
- Digital conductivity meters monitor resin cartridge performance
- Flow counters track resin usage over time
- Magnesium anode visual checks ensure protection in mixed-metal systems
These simple diagnostic tools mean even non-technical users can assess system health - an especially important feature in commercial buildings, schools, and housing developments where service access may be limited.
VDI 2035: growing UK adoption
VDI 2035 has long been standard practice in Germany and other parts of Europe, but its uptake in the UK is accelerating. In recent years, industry leaders such as LSAT UK and Caleffi have begun supplying VDI-compliant products, making it easier for UK installers to adopt the approach.
Is VDI 2035 suitable for heat pumps and district heating?
The short answer is, yes. In fact it’s also now recognised in CP1 (Heat Networks: Code of Practice), marking a significant step forward in aligning UK standards with low-carbon, low-maintenance practices.
Why does VDI2035 matter for UK heating systems?
The rise of low-carbon heating systems, such as heat pumps and district energy networks, requires a fresh look at traditional maintenance methods. Chemical-free water treatment supports this shift by offering:
- Lower long-term maintenance costs
- No chemical handling, storage, or disposal concerns
- Improved compatibility with sensitive system components
- A sustainable, environmentally friendly approach
For engineers, developers, and facilities managers seeking a reliable, long-term solution for system protection, VDI 2035 is proving itself as a credible and effective alternative.
Conclusion
While traditional chemical treatments will always have their place, the simplicity and effectiveness of VDI 2035 offer compelling benefits. By removing the root causes of corrosion rather than treating the symptoms, this German-engineered approach is set to become an essential tool in the UK heating industry’s toolkit, especially as the sector moves toward more sustainable and efficient technologies.
Check out Altecnic's chemical free water treatment solutions here.
AUTOMATIC COMPACT CHARGING UNIT
Automatic compact charging unit with BA-type backflow prevention valve.
The compact automatic charging unit is composed of a shut-off valve with an inspectable strainer, a BA-type controllable reduced pressure zone backflow preventer and an automatic filling unit. It is installed on the water inlet piping in closed circuit heating systems. It maintains the pressure of the system stable at a set value, automatically topping up with water as required. The backflow preventer prevents the contaminated water of the closed heating circuit from flowing back into the domestic water supply, in accordance with the provisions of EN 1717. The device is supplied complete with preformed shell insulation and features a compact design to facilitate installation.
AUTOMATIC WATER TREATMENT UNIT
The automatic water treatment unit, installed on the inlet pipe, is used to treat water in the closed circuits of heating and cooling systems. It consists of an upstream check valve, an electronic controller with positive displacement meter and electrical conductivity measuring cell, a by-pass regulator, a downstream ball shut-off valve and adjustable drain cocks and air vent. It can be set up with different types and sizes of cartridge, which means demineralisation or softening treatments can be performed in line with system requirements. It is complete with pre-formed shell insulation, bracket and anchors for wall mounting.
ELECTROLYTIC SCALE REDUCER
The Altecnic Dirtmag IQ electrolytic scale reducer is not a water softener but induces coagulation whilst the water hardness remains unchanged.
It works in the same way as a small battery where the copper body (cathode) and internal zinc (anode) are connected via mains water (electrolyte) to alter the structure of the hardness salts.
As charged zinc ions are emitted from the anode they form a nucleation site for colloidal particles (such as hardness salts) to group around, rather than clinging to heat exchangers or pipe-work.
Limescale deposits are more common where heat is generated and can have lasting damaging effects on the efficiency and life of the boiler. The Dirtmag IQ electrolytic scale reducer benefits a range of appliances including kettles, taps, showers and boilers.
