Protections; Thermal Protection Of The Ch Boiler; Automatic Sensor Control; Thermal Protection Of The Ch Boiler (Stb) - Tech Controllers ST-976 User Manual

P
ROTECTIONS
In order to ensure safe and failure‐free operation, the regulator has been equipped with a
range of safeguards. In case of alarm, a sound signal is activated and the display shows an appropriate
message.
T
HERMAL PROTECTION OF THE CH BOILER
The controller is equipped with a bimetallic mini‐sensor (placed next to CH boiler temperature sensor), which
automatically disconnects the fan from the power supply when the alarm temperature of 90°C is exceeded. It
prevents the water in the installation from boiling in case of CH boiler overheating or controller damage. After
this protection has been activated and the temperature has dropped to a safe level, the sensor automatically
unlocks itself. If this sensor is damaged or overheated, the fan is also disconnected.
In the case of CH boiler protection in a closed system, a STB type temperature limiter is used instead
of a bimetallic mini‐sensor.
A
UTOMATIC SENSOR CONTROL
If one of the temperature sensors (CH, DHW) is damaged, an alarm sound is activated and the display message
informs about the failure; e.g.: CH sensor damaged. The fan is disabled. The pump is enabled regardless of the
current temperature.
If the CH sensor is damaged, the alarm is active until a new sensor is installed and the CH boiler is disabled.
In the case of DHW sensor damage, the alarm should be switched off by pressing
will deactivate the alarm and restore operation (the modes involving DHW tank will not be available). A new
sensor should be installed so that all modes of CH boiler operation could be available.
T
HERMAL PROTECTION OF THE CH BOILER
In a closed CH system, the controller is equipped with STB safety thermostat which protects the CH boiler
against an excessive temperature increase. When the temperature exceeds the pre‐set 'switch off' value
(default setting: 95
only manually by pressing 'reset' on the safety thermostat casing after the sensor cools down.
F
USE
The regulator has a WT 6.3A tube fuse‐link protecting the network.
WARNING
Higher amperage fuse should not be used as it may damage the controller.
44
o
C), the contacts in the fan power supply circuit are opened. The fan may be activated again
(STB)
– the controller