de Jong Duke COEX 9CND SERIES, Technical Manual

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Temperature safety / clixon:
The temperature safety switch is positioned on the side of the boiler. In the
housing is a bi-metal disk which switch if the device gets too hot.
This safety protects the heater against overheating if the control system does not
switch off the heater.
The temperature safety (normally closed contact) switches off at a temperature of
110ºC +/- 5ºC. The safety switches the current to the heater directly off if the
boiler is overheating. The clixon is resettable after cooling down by pressing the
pin by hand.
Temperature/Level sensor:
The sensor in the boiler is a combined level and temperature probe. The sensor is
isolated from the boiler housing with a plastic isolation clamped with two nuts
around the stainless steel sensor housing.
If replacement is needed the sensor needs to be replaced complete, including
nuts.
Temperature:
The temperature is detected by a thermistor mounted in the stainless steel
housing. The control system is controlling the temperature in the boiler based on
the resistance of the thermistor.
Resistance of the thermistor:
Resistance Temperature
6.5 k  95ºC
100 k  25ºC
126.7 k  20ºC
The temperature is adjustable in the settings of the control system.
The optimal temperature setting is 90ºC in boiler 1 and 92 ºC in
boiler 2. If no consumptions are made, the temperature in boiler 2
will automatically raise in about 25 minutes to 98º. Herewith the
first consumption with a cold brewer is brewed with incoming water
on a higher temperature, compensating the colder brewer.
The control system contains some safeties and warnings based on
the detected value of the temperature sensor.
A too high temperature, too low temperature, shortcut or
disconnected sensor is detected by the control system.
- Disconnected temp. sensor is generated if the resistance is above 350 k  .
- Shortcut temp. sensor is generated if the resistance is below 1 k 
Reset
pin