Calculated heat demand

The heating coil calculates the heating demand for the heating control strategy as a function of the actual position of the heating valve. When the heating valve is open more than 50% plus the value defined by the parameter HTG-05, the calculated heating setpoint will be ramped up stepwise by the value defined by HTG-04 (K/min). When the heating valve is open less than 50% minus the value defined by HTG-05, the calculated heating setpoint will be ramped down stepwise by the value defined by HTG-04. During the time the valve position remains in the higher or lower zone, the setpoint will continuously ramp up or ramp down. When the valve position returns into the zone between the minimum/ maximum value, the setpoint remains unchanged. If the heating valve closes to 0%, the setpoint is set to 0°C. When the heating valve starts to control after a closed position, the calculated heating setpoint is reset to its start value, which is defined in the parameter HTG-03. When the valve is in the control mode, the calculated heating setpoint remains within the minimum and maximum values defined HTG-01 and HTG-02 as shown in the next figure.



Description

Default value

HTG-01: calculated heating setpoint supply temp. min. setpoint

20 °C

HTG-02: calculated heating setpoint supply temp. max. setpoint

85 °C

HTG-03: calculated heating setpoint supply temp. start point

50 °C

HTG-04: heat demand increase/ decrease value

1 K/min

HTG-05: heating valve pos. diff. to calculate heating setpoint

25 %