Increasingly used, yet still not known to everyone… What are corrosion inhibitors, do they always help, what is worth knowing about them? When is it worth using them? Are there any risks or contraindications associated with corrosion inhibitors?
A corrosion inhibitor is a chemical substance that can be one of the key elements in protecting water, heating, and industrial installations against material degradation. What kind of degradation are we talking about? Of course, corrosion and scale buildup, rather in the long term. In some conditions, heating systems are more exposed to these processes – in others slightly less, but over the years every water installation is at risk of certain substances precipitating from the water, which then deposit as scale or contribute to system degradation from the inside or to corrosion.
The task of a corrosion inhibitor is therefore to prevent this. The goal is to reduce or completely stop corrosion processes that arise as a result of metal coming into contact with water, oxygen, and other chemical factors. In practice, this means extending the service life of the installation and maintaining its efficiency at a high level for many years. They are used to extend the lifespan and full efficiency of the system – as well as to reduce the failure rate of individual system components. And these components can be quite important (and expensive) – e.g. a heat pump, a condensing boiler, or slightly smaller ones such as a circulation pump, a plate heat exchanger, a hydraulic separator, or a manifold.
Corrosion is a natural electrochemical process that leads to the gradual destruction of metal elements such as pipes, heat exchangers, boiler manifolds, or boilers. In central heating systems, steel and aluminum components are particularly exposed. A corrosion inhibitor works by creating a protective layer on the surface of the metal, which limits contact with factors that cause oxidation. As a result, the corrosion process is significantly slowed down or stopped.
The use of corrosion inhibitors is especially important in closed (pressurized) systems, such as central heating systems – which may seem somewhat surprising at first glance, as many people consider closed systems to be much safer and less prone to scale buildup and corrosion formation. On the one hand, this is indeed true – these systems are undoubtedly less exposed to degradation than open systems.
However, another aspect should also be considered. In such systems, water circulates for many years, and its quality has a direct impact on the technical condition of the entire installation. Even a small amount of oxygen or contaminants can lead to the formation of deposits, rust, and so-called magnetite. Regular use of inhibitors helps limit these phenomena and keep the installation clean.
The use of corrosion inhibitors can be particularly beneficial in underfloor heating systems, because due to the use of pipes with relatively small cross-sections, maintaining proper flow is especially important. Alternatively, it is possible to use magnetite filters (i.e. dirt separators) – they capture degraded elements of the system, but this is not a solution that excludes the use of corrosion inhibitors, but rather one that complements them very well.
When should a corrosion inhibitor be used? Preferably already at the stage of the first filling of the installation. Adding an appropriate preparation to a new installation protects it from the very beginning and minimizes the risk of corrosion centers forming. It is also worth using an inhibitor after any intervention in the system, such as component replacement, draining water, or system modernization. In such situations, air enters the system, which accelerates corrosion processes.
A corrosion inhibitor should be selected according to the type of installation and the materials it is made of. Different preparations are used in steel installations, or in those with numerous steel components (e.g. INOX manifolds) – and others in mixed systems (e.g. steel + aluminum), and still others in systems made of plastics. It is also important to match the product to the type of heating medium – whether it is pure water or, for example, a glycol solution used in installations exposed to freezing, e.g. in glycol circuits of heat pumps.
The preparation is most often introduced directly into the installation via a drain valve, air vent, or a special dosing device. Very often, the function of adding corrosion inhibitors or other protective substances to systems – the so-called system flushing function – is provided by magnetic filters.
Maintaining the correct concentration is crucial in accordance with the manufacturer’s recommendations. Too small an amount of the product may be ineffective, while an excess does not bring additional benefits and may affect the operating parameters of the installation, i.e. temporarily or permanently reduce heat output from radiators or underfloor heating, which would not be desirable. After adding the inhibitor, it is worth starting the circulation to evenly distribute the preparation throughout the entire system.
Regular inspection of the installation condition and water quality is another important aspect. In some cases, it is recommended to periodically check the inhibitor concentration and replenish it if necessary. This particularly applies to older or heavily used installations. This helps avoid costly failures such as leaks, performance drops, or damage to pumps and heat exchangers.
A corrosion inhibitor is an inexpensive but extremely effective way to protect heating and water installations. Its use significantly extends the lifespan of the system, improves efficiency, and reduces the risk of failures. It is worth treating it not as an option, but as a standard element of every modern installation.
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