TECH ST-81 - User Manual

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Overview

Function Description
Important Technical Specifications
Usage Features
Maintenance Features

The ST-81 is a microprocessor-controlled temperature regulator designed for central heating boilers, specifically wood-fired models. It manages both the water circulating pump and the air injection fan.

Function Description

The ST-81 controller offers various functionalities to optimize boiler operation:

Temperature Regulation: The primary function is to maintain a set boiler temperature. If the boiler temperature is below the set value, the blower operates continuously. Once the boiler temperature reaches or exceeds the set value, the controller enters a temperature maintenance mode.
Flue Gas Outlet Temperature Monitoring: Users can check the flue gas outlet temperature by pressing the EXIT button for several seconds. The display will show the boiler temperature, flue gas outlet temperature, and fan power.
Firing-up Function: This allows the user to switch the fan on or off during continuous operation. If the boiler temperature is above 30°C but below the set value, the fan can be enabled or disabled. An asterisk on the display indicates when the fan is enabled. This feature is crucial for safe boiler operation, emphasizing that the furnace door should not be opened when the fan is on.
Manual Operation: The controller supports a manual mode, enabling independent switching of all connected elements, such as the blower and central heating water pump. The OPTIONS button is used to toggle these components.
Pump Activation Temperature: This function allows setting the activation temperatures for both the Central Heating (CH) pump and the Utility Hot Water (UHW) pump. Both pumps remain inactive below the set temperature. Once the set temperature is exceeded, they activate, operating based on other settings like pump priority or continuous CH pump mode.
Boiler Hysteresis: This setting defines the temperature difference between the activation of the temperature maintenance mode and the restoration of the operation mode. For example, if the set temperature is 60°C and hysteresis is 2°C, maintenance mode activates at 60°C, and operation resumes at 58°C. The hysteresis value can be set between 2°C and 6°C.
UHW Hysteresis: Similar to boiler hysteresis, this sets the temperature difference for the UHW pump's operation. If the set temperature is 55°C and UHW hysteresis is 5°C, the UHW pump turns off and the CH pump activates at 55°C. The UHW pump reactivates when the temperature drops to 50°C.
UHW Pump Priority (Boiler Priority Mode): Activating the UHW pump (by selecting "TURN ON") switches the controller to boiler priority mode. In this mode, the UHW pump operates until the set temperature is reached, then turns off, and the CH circulating pump activates. The UHW pump's set temperature can be adjusted via the EXIT button. This mode prioritizes heating utility hot water first, then radiator water.
Summer Mode: In summer mode, the CH pump is deactivated, and the UHW pump operates continuously above its activation temperature. This mode allows adjusting only the boiler set temperature for heating water in the vessel. The display shows boiler temperature (CH), vessel temperature (UHW), and the set temperature.
Fixed CH Pump Mode: In this mode, both pumps activate concurrently above the set temperature. The CH pump operates continuously, while the UHW pump deactivates upon reaching the boiler's set temperature. This mode requires a three-way or mixing valve to manage different environmental and boiler temperatures.
Default Settings Restoration: The controller comes with default settings, which can be restored at any time, deleting all customized parameters.

Important Technical Specifications

Power Supply: 230V/50Hz +/-10%
Power Input: 2W
Environment Temperature: 10°C to 50°C
Circulation Pump Output Load: 1A
Fan Output Load: 1A
Temperature Measurement Range: 0°C to 85°C
Measurement Accuracy: 1°C
Temperature Setting Range: 30°C to 80°C
Temperature Sensor Durability: -25°C to 100°C
Fuse: WT 2.5A

Usage Features

LCD Display: The controller features an LCD display that shows current boiler temperature, set temperature, and other operational information.
Navigation: Navigation through menus and settings is done using PLUS and MINUS buttons. The OPTIONS button enters submenus or confirms selections, while the EXIT button returns to the parent menu.
Quick Set Temperature Adjustment: The main screen allows for quick adjustment of the set temperature using the PLUS and MINUS buttons.
Safety Measures:
- Thermal Protection: An auxiliary bimetal mini-sensor cuts off the fan output if the temperature exceeds 85°C, preventing system boiling. This limiter automatically restores to the starting position.
- Automatic Sensor Control: In case of CH temperature sensor failure, an alarm activates, and an "ALARM SENSOR FAILURE" message is displayed. Pressing the OPTIONS button restores normal operation.
- Temperature Protection (Bimetal Sensor Damage): If the bimetal sensor is damaged and the temperature exceeds 85°C, an alarm activates, displaying "ALARM EXCESS TEMP".
- Boiling Protection: This function prevents excessive boiler temperature. If the boiler set temperature is, for example, 55°C and the current temperature reaches 62°C, the fan activates. If the temperature continues to rise to 80°C, the CH pump activates. An alarm sounds at 85°C. If the temperature drops to 60°C, the blower restarts and continues until the set temperature is reached.
- Fuse Protection: The controller is equipped with a WT 2.5A fuse. It is critical not to use a fuse with a higher ampere value, as this could damage the controller.

Maintenance Features

Pre-Season Inspection: Before and during the heating season, the technical condition of the ST-28 controller's wires should be inspected.
Mounting and Cleaning: The controller's mounting should be checked, and dust or other contaminants should be removed.
Grounding Efficiency Measurement: Measurements of the grounding efficiency for the electric motors (CH pump, UHW pump, and fan) must be taken.
Non-Return Valves: For optimal and safe operation, the boiler should be fitted with non-return valves in both the CH and UHW circulation systems. These valves prevent hot water discharge from the boiler (UHW pump valve) and hot water from entering the house (CH pump valve).
Installation by Certified Electrician: All installation steps, including connecting wires, must be performed by a certified electrician. The device should not be connected to the mains during installation.
Ground Conductor Connection: Special attention should be paid to ensuring the ground conductor is properly connected during installation.
System Requirements: The controller cannot operate in a closed central heating circulation system without safety valves, pressure valves, and a surge tank to prevent water boiling.
Technical Support: Any defects or issues should be reported to TECH Sp.j. at their provided address and contact numbers. Service notices are accepted Monday to Friday from 7:00-16:00 and Saturday from 9:00-12:00.

TECH ST-81 Specifications

General

Brand	TECH
Model	ST-81
Category	Controller
Language	English