Myth #1: Thick walls, no seams, or a smooth inner surface are immune to corrosion.
Cast iron radiators are not easily corroded due to the inherent anti-corrosion properties of cast iron, not because of their wall thickness. In recent years, some domestic small manufacturers have tried to address the anti-corrosion issue of steel radiators by increasing wall thickness. However, experts have pointed out that corrosion is unrelated to wall thickness. The corrosion of steel radiators is localized pitting corrosion, not uniform corrosion.
Moreover, claims by some manufacturers such as "no seams, clean and smooth interior" do not contribute to the anti-corrosion properties of radiators. Because the corrosion of steel radiators does not occur at the seams and is not uniform. Instead, it is localized pitting corrosion. Therefore, the absence of seams or a smooth interior does not equate to zero corrosion.
Myth Two: Copper radiators (or aluminum radiators) do not corrode.
Generally, copper has better corrosion resistance than steel; however, under certain conditions, copper radiators can also suffer from corrosion. For instance, the presence of silt in pipes, excessive sulfur content, or a carbonized layer on the copper surface can all lead to corrosion of copper radiators.
2. Corrosion principles vary among different materials. While aluminum radiators have strong resistance to oxidation and corrosion, they are prone to alkali corrosion and chloride ion corrosion. Therefore, when the water quality of a heating system is alkaline (pH value above 7) or contains a high concentration of chloride ions (high salt content), there is a hidden risk of corrosion and leakage in the radiators.
Due to the poor welding performance of aluminum alloys, it is recommended that consumers avoid using aluminum alloy radiators with seams.
Myth Three: Internal coating is just for corrosion prevention.
The common anti-corrosive coatings used inside radiators are divided into two categories: one is inorganic coatings, represented by zinc chromate salts, and the other is organic coatings. Currently, most domestic brands on the market select these two types of organic coatings for their radiators. Additionally, many manufacturers to save costs omit certain processing steps, conducting only a single internal coating treatment. The coating thickness typically does not exceed 30 micrometers. Consequently, many internally coated radiators on the market start to develop large-scale bubbles and the coating begins to peel off after about 5 days of soaking in hot water, failing to effectively prevent corrosion.
Tip: Radiators made of thin aluminum or steel with high thermal conductivity may not be suitable for all homes. Before purchasing, it's important to understand the water quality of the community's heating system. If it's geothermal heating water or water that hasn't been deoxygenated, steel radiators should not be used as they are more prone to corrosion. In areas with high water pressure, aluminum radiators with welds should be avoided, as their strength is slightly inferior and they are more likely to leak.