Retrofittable control unit for a softening apparatus

Control unit for a softening device, wherein the control unit comprises:

• a primary inlet for untreated water;
• a primary outlet for blended water;
• a sensor for determining the water hardness of the untreated water WHraw or the blended water WHblend;
• a secondary outlet which is supplied with untreated water from the primary inlet;
• a secondary inlet which is supplied to the primary outlet;
• a bypass line connecting the primary inlet and primary outlet and which is guided parallel to the secondary outlet and the secondary inlet, wherein the bypass line is configured to supply the untreated water from the primary inlet to the primary outlet and wherein the bypass line is disposed internal to a control unit;
• a blender which can be automatically adjusted for mixing a blended water flow V(t)blend from a first partial flow V(t)part1soft of the secondary inlet and a second partial flow V(t)part2raw of the bypass line;
• an electronic control means configured to readjust the adjustment position of the blender according to the determined water hardness WHraw or WHblend in such a fashion that the water hardness in the blended water flow V(t)blend is adjusted to a predetermined desired value;
• wherein the control unit is designed in the form of an external control unit for the softening device, wherein the control unit has a control unit housing, the outer side of which is provided with the primary inlet, the primary outlet, the secondary outlet and the secondary inlet, and wherein the control unit housing completely contains the sensor, the entirety of the bypass line, the blender and the electronic control means, and wherein the blended water flow V(t)blend is configured to be blended from the first partial flow V(t)part1soft and the second partial flow V(t)part2raw within the control unit housing.