Heat-Flow Sensor (Wfs); Fault Repair; Knocking Noises - Miele DGC 6 Series Technical Information

Technical Information

At temperatures above 214°F, the absolute humidity is displayed and
can be set by the user. To avoid confusion, the humidity level is
indicated in percent by volume.
2.5.5

Heat-Flow Sensor (WFS)

A heat-flow sensor is used to measure the level of humidity in the cavity.
The heat-flow sensor is located in the cavity very close to the temperature
sensor at the top right. This means that both sensors have identical ambient
temperatures. The heat-flow sensor has cooling vanes and is installed in an
additional air duct. This air duct, that is open at the rear of the appliance, is
supplied with ambient air by the cooling fan. This ensures that the heat-flow
sensor is always cooled by sufficient cool air. The cooling fan expels the
ambient air in the area behind the fascia panel. This air is passed out of the
appliance via its cooling system. The sensor contains two Pt1000
temperature sensors.
The heat-flow sensor is cooled with ambient air by a cooling fan. The sensor
plate is located in the cavity. The sensor is separated from the cavity walls by
insulation. This prevents the transfer of heat through the cavity walls. As the
heat-flow sensor is cooled by the cooling fan, the front of the sensor is the
coldest point in the cavity. Humidity therefore first condenses at this point.
This causes the temperature at the sensor to rise because the water is a
better conductor of heat to the sensor interior. After the temperature has risen
at the first measuring point, it also rises at the second measuring point. As
there is a fixed defined path between the two measuring points, differences
and changes can be used to deduce the level of humidity in the cavity. The
basic principle is that the greater the level of humidity in the cavity, the higher
the temperature at the heat-flow sensor.
3

Fault Repair

3.1

Knocking Noises

Symptom:
When the feed pump passes water into the steam generator, knocking noises
can be heard.
Cause:
The noise is cause by the rapid expansion of the cold water as it changes
state to steam when it comes into contact with the hot water already in the
steam generator.
Remedy:
None.
Cause:
Due to the shape of the drip shield in the steam generator, the cold water
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DGC 6xxx