Oversizing a heat exchanger simply means installing a model with greater capacity than mathematically required by our installation.
✅ A properly selected hydraulic device almost always needs to have an additional power reserve - including in the case of a heat exchanger, although there are of course common-sense limits to oversizing, above which it makes no sense to go.
Heat exchanger is a device that, like any other, wears out over time. In a hydraulic installation, it is subjected to various temperatures, pressures, and above all, contact with media, which over time cause scaling. The efficiency of the heat exchanger is mainly determined by the so-called heat exchange surface, which decreases as it becomes covered with scale. Unfortunately, scaled parts of steel plates no longer exchange heat between fluids - which means a systematic decrease in the efficiency of the exchanger from season to season. Hence, selecting an exchanger to be "on the edge" is sometimes only suitable for 1-2 seasons.
✅ Then the problem of scale begins, the exchanger reduces its actual efficiency and de facto becomes a device unable to transfer full thermal power. That's why some extra capacity in advance - is quite a good idea.
A decline in heat exchange efficiency begins to be felt through cooler radiators and warmer return to the boiler than in the first heating season. This also leads to a gradual increase in fuel consumption by the heating device, resulting in higher heating costs. To avoid such a situation, it is simply worth using an oversized heat exchanger. The additional power will ensure that even after several years, we will not experience a decrease in heating efficiency.
✅ Is it possible to prevent scale buildup? To a large extent, yes (e.g., by installing water softeners), but it is a process that is not entirely avoidable. There are special descaling preparations and related devices on the market, but every exchanger has its lifespan, which cannot be unlimited.
✅ Oversized units can serve even for 10-15 seasons, while those selected on the edge typically last 2-4 seasons.
Oversizing the heat exchanger is harmless, even substantial. However, using much larger exchangers than we need entails significant costs, which at some point cease to be justified. A properly selected exchanger is oversized by 20-50% in relation to the required heating power. However, we pay attention to the achievable performance in the specific installation parameters, rather than the nominal power, which is often calculated for high, more favorable parameters than in domestic installations.
✅ In this case, it is best to seek assistance from specialists in the selection process. If you need help selecting an exchanger, take advantage of the free advice and contact us.
NORDIC Tec Team
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History of plate heat exchangers
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Berechnung Wärmetauscher für Solar und Pufferspeicher
By: Hinsberger On 2025-04-21Good evening, I need your assistance.
I believe my heat exchanger is too small. It cannot transfer the heat generated by the solar system to the storage tank.
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Translated from the original text:
Guten Abend ich bräuchte Ihre Unterstützung.
Ich denke mein Wärmetauscher ist zu klein. Er kann die erzeugte Wärme der Solaranlage nicht in den Speicher übertragen.
Mit freundlichen Grüßen
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Replied by: Adam Bert On 2025-04-21