Caused by several metals in the heating installation (copper tubes, sheet steel reservoir, brass mountings, etc.) and the salt soluted in water the heating begins to corrode and to silt up (see picture).
ZIRKO-Protect solves this problems. This gel produces a fine water-repellent coating in the tubes and increases the durability of your heating. Details: zirko-protect.de (up to now only German language website).