De Dietrich S101766 cartuccia 8 ltr

This is a replacement cartridge for a three-way mixing valve, with a capacity indicated as 8 litres. In a heating system, three-way and four-way valves divert or blend flow between the boiler circuit and the heating or hot-water circuits. The cartridge is the internal hydraulic assembly that contains the plug and the sealing surfaces; it is the part that directly controls the passage of water between the valve ports. The motor that drives the cartridge is usually a separate spare part. When selecting a cartridge of this type, the critical parameters are the nominal diameter, the pressure and temperature rating of the system, and the flow characteristic (linear or equal-percentage). The 8‑litre reference likely relates to the valve’s flow capacity or the volume of water it can handle, but you must match the cartridge to the valve body’s bore and to the original manufacturer’s specification. Common failures in such cartridges include seizure of the valve stem after a prolonged period of standstill, especially at the end of the heating season, and internal leakage caused by worn sealing faces or debris in the water. When replacing this cartridge, drain the system, remove the actuator (motor), and then extract the old cartridge from the valve body. Clean the valve body bore thoroughly, check the O-rings or gaskets for damage, and fit the new cartridge. Ensure that the stem orientation and any positioning marks align with the valve body before refitting the motor. Always verify that the replacement cartridge is intended for the same valve body series, as dimensions and port configurations vary between manufacturers.