Vii.c) Temperature Protection; Vii.d) Protection Against Water Boiling In The Boiler; Vii.e) Fuse; Viii. Maintenance - Tech Controllers ST-81 User Manual

User's manual
If the CH sensor is damaged, the alarm will be active until the sensor is replaced with a new one. If
the DHW sensor is damaged, the user should press the MENU button, which deactivates the alarm and
the controller returns to one pump operation mode (house heating). In order for the boiler to operate
in all modes, the sensor needs to be replaced with a new one.
Temperature Protection
VII.c)
The regulator is equipped with additional protection in the
event of damage to the bimetallic sensor after exceeding the
temperature of 85°C, the alarm is activated showing the
following on the display:
The current temperature is read from the electronic sensor and processed by the temperature
regulator. If the emergency temperature is exceeded, the fan is disconnected and both pumps start
operating simultaneously in order to distribute hot water throughout the system in the house.
Protection against Water Boiling in the Boiler
VII.d)
This protection applies only to the operation mode 'Boiler Priority' if the tank is insufficiently heated.
When the boiler temperature is pre-set, e.g. at 55⁰C, and the actual temperature in the boiler
increases to 62°C (this is the so-called priority temperature), then the controller will switch the fan
off. If the temperature on the boiler increases to 80⁰C, the CH pump switches on, in order to distribute
hot water in the system. When the temperature still increases, the alarm activates at the temperature
of 85°C. Such condition may appear when the boiler is damaged, the sensor is improperly fastened or
the pump is damaged. However, if the temperature drops, the controller will switch the airflow on at
the temperature of 60°C and will run in the operation mode oscillating around the priority temperature
(factory value - 62°C). The priority temperature in this mode is the boiler's temporary pre-set
temperature until the boiler's tank is additionally heated.
Fuse
VII.e)
The regulator is equipped with two tube fuse links WT 3.15 A protecting the controller.
NOTE
Higher amperage fuse should not be used as it may damage the controller.

VIII. Maintenance

Before and during the heating season, the ST-81 controller should be checked for the condition of its
cables. The user should also check if the controller is properly mounted and clean it if dusty or dirty.
The user should also measure the earthing effectiveness of the engines (CH pump, DHW pump and
the fan).
TECHNICAL PARAMETERS
Item Specification
1 Power supply
2 Power consumption
3 Ambient temperature
4 Load of circulating pump outputs
5 Fan output load
6 Range of temperature measurement
7 Measurement accuracy
8 Range of temperature settings
9 Temperature endurance of the sensor
10 Fuse link
Alarm
CH temp too high
Unit
V
W
⁰C
A
A
⁰C
⁰C
⁰C
⁰C
A
14
230V/50Hz +/-10%
5
5÷50
0,5
0,6
0÷90
1
45÷80
-25÷90
2x3,15