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Versions without weather compensation
A dedicated boiler relay is provided to enable the boiler to run if there is a demand for heat. The boiler relay will be energised ON 1 minute after the main pump has started. A built-in delay action creates a 5 minutes pause between OFF/ON actions to prevent short cycling of the boiler. The boiler relay is a 4-amp switch, and is volt free.
Versions with Weather Compensation
The boiler relay will be ON once the mixing valve has reached 20% open, and will remain ON as long as a heating demand exists. The boiler relay is a 4-amp switch, and is volt free. Water Temperature Control
The WLM-1FS and WLM-3FS master has provision for the limitation of the supply water temperature via a 2, 3, or 4 way control valve.
A water temperature sensor is mounted on the supply side to the system, after the control valve, and a maximum water temperature setting is programmed in the master control.
A default setting of 45°C is factory set but is adjustable on site between 30°C and 70°C, to suit the floor construction used.
The control valve will be opened by the master when a demand for heat exists, but will be modulated to maintain the supply water temperature at the required level, by closing down the input of boiler water if the actual water temperature exceeds the maximum setting. Once the room thermostats in the system are satisfied, the valve will be closed.
Weather compensation
The supply water temperature to the system can be automatically varied in relation to outdoor temperature, so that water at the correct temperature is supplied to the system. The master will position a 2, 3, or 4 way control valve to maintain the correct flow temperature. The correct temperature is calculated by the master, taking into account the heat losses that will vary depending on the outdoor temperature, and the room temperature requirements of the system. For example, on a day when the outdoor temperature is 12°C, it is possible to run the heating system with a supply water temperature of only 35°C. This ensures the most economical running of the boilers, and comfortable room conditions throughout the year.
The master WLM-1FS and WLM-3FS is supplied already prepared for weather compensation and simply by adding an outdoor compensation module on the 2-wire bus and using the water temperature sensor on the supply water side, you have a control system for weather compensation. The max. allowed supply water temperature is your assurance against excessive water temperature at -30°C outdoor temperature.
Preset values are programmed at the factory, but these values can easily be adjusted according to local needs via the backlit display, using icons to indicate the setting options.
Control Valve Output
The control valve is positioned using a 24V AC actuator (max power 6VA) via a 0-10V DC signal.
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