✅ Water is water... what’s different about groundwater, rainwater, deep well water, or, generally speaking, untreated water?
Hydraulic devices, virtually all those distributed in Europe today, are designed for the civilizational standards prevailing in European countries. In 95% of cases, they are intended to operate in cities and villages where water comes from the municipal water supply. Every country has legislation requiring public or municipal water companies to pre-treat water and specifies norms for the content of various elements, making the water not only human-friendly but also suitable for household appliances and fittings. Of course, these norms are sometimes not fully met, but in most cases, such water meets basic standards—ensuring it is not considered particularly aggressive or highly damaging to domestic hot water tanks, heat exchangers, bathroom and kitchen fittings (such as taps and showerheads), household appliances, and especially expensive items like gas boilers or heat pumps.
The norms certainly don’t solve the issue of hard water, which covers most of the country’s territory, but even in this regard, water from public suppliers is of much better quality than groundwater, rainwater, or water from rivers or lakes.
Brazed plate heat exchangers are generally efficient and compact devices, but their construction (especially the fact that they are made of plates as thin as 1/3 mm) makes them sensitive to water quality, particularly groundwater. Groundwater often contains iron, manganese, calcium, magnesium, and other impurities, which can lead to greater limescale deposits, clogging of flow channels, and corrosion of brazing (yes, copper brazing can also corrode in improper conditions). The lack of proper water treatment can result in reduced efficiency, device failure, and increased operating costs.
✅☑️ Therefore, if you are looking for a heat exchanger for groundwater, you should be aware that a standard plate heat exchanger is not designed for this purpose.
Many people are surprised to hear that the stainless steel from which a typical brazed heat exchanger is made may not withstand working with groundwater or deep well water. They fail to consider that the plates of the exchanger must be ultra-thin (to increase the heat transfer coefficient). Using thicker plates could make the exchanger more durable against water with excess iron, calcium, manganese, or magnesium, but it would significantly increase costs and the size of the device. Since 99% of heat exchangers are designed to work with treated water, it becomes economically unjustifiable.
If you need a heat exchanger for groundwater or deep well water—generally speaking, untreated water—you must ensure (preferably by asking the seller) that the exchanger can be used in such a harsh environment. From experience, we know that there are cases where someone looks for a heat exchanger for groundwater used as a so-called lower source for a heat pump. These people often claim, "but groundwater can't be that harmful," which always surprises us in the context of their intention to protect the heat pump from it... water that often exceeds all iron content standards and sometimes even contains salt.
✅☑️ The best option in this case is either a titanium heat exchanger (though these are quite expensive) or a bolted, frame plate heat exchanger. A frame plate heat exchanger is disassemblable (unlike brazed exchangers), and there are gaskets between the plates. Needless to say, such components can be replaced if they wear out. While this device requires occasional maintenance, it is the only effective solution.
Nordic Tec, like many manufacturers, conditions its warranty on the use of pre-treated water. Usage with water exceeding iron content standards, for example, is relatively easy to detect during a warranty claim process and results in the warranty being voided due to improper use of the product. We can add that, according to statistics kept by the manufacturer, 72% of warranty claims or leaks in heat exchangers were due to operation with untreated water, usually groundwater, deep well water, or rainwater—sometimes river water or water directly from a well (in cooperation with a heat pump).
Similarly, manufacturers of heat pumps, gas boilers, electric boilers, and domestic hot water tanks also have clear requirements regarding basic water quality, and failure to meet these standards definitively voids the warranty on the device.
Water with elevated iron content, known as iron-laden water, can cause many negative effects, particularly in hydraulic systems and water installations:
Water hardness refers to a high content of calcium and iron, as well as manganese and magnesium. Its legally established limits generally hover around 500 mg per liter of water. Many experts believe that water hardness significantly below this value already has extremely harmful effects on household appliances, storage tanks, water filters (e.g., UV filtration lamps), and heat exchangers. However, by consensus, it is likely acknowledged that it is challenging to ensure less hard water in practice when dependent on the water resources available in our country. In fact, almost every country in Europe struggles with hard water.
Nevertheless, it should be understood that water from private sources—e.g., private wells or river water—does not undergo any form of preliminary treatment, and this standard may be significantly exceeded. This explains why hard water can lead to the leakage of heat exchangers, even if their standard lifespan is estimated to last many years.
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