Boiler loading

This function block is used to implement boiler loading.

Inputs
FW	Enable hot water	Enable hot water heating. Input is optional, if no variable is linked to the input, the block is always enabled.
FL	Release legionella	Enable legionella heating. The legionella heating is started with a positive edge at the input. When this temperature is reached, 0 is sent to the linked variable and the setpoint for hot water is used again. The variable at the input can, for example, be set to 1 by a time switch. When the legionella heating is finished, the variable is set to 0 again by the module.
T1	Boiler top*	Actual temperature boiler top.
T2	Boiler below*	Actual temperature boiler down.
SW	Target hot water*	Set temperature hot water
SL	Shall legionella	Legionella set temperature
Outputs
AB	Request bit	Output is set to 1 when boiler is heated. This output can be used for a pump or enable heat generator.
AP	Requirement percent	Current setpoint temperature in percent. This is set with the parameter Factor percentage output.
AT	Request temperature	Current set temperature in degrees.
ST	Status	Status Bit-coded. Bit 0 = Legionella heating active.
Parameter
Hysteresis on		Set hysteresis for hot water preparation. If the temperature of the boiler falls below the upper set point minus the hysteresis, the water heating is started.
Hysteresis off		Hysteresis for water heating off. If the temperature of the lower boiler exceeds the set point plus the hysteresis and the upper boiler is higher than the set point, water heating is terminated.
Offset set temperature		This parameter is added to the Request temperature output. This can be used for a setpoint boost.
Factor percentage output		This parameter is used to set the percentage output. This is the temperature at 100 percent. With a value of 80, 100 percent is output at setpoint temperature 80, 50 percent at 40 degrees, and so on. The Offset setpoint temperature parameter is added to the calculation.

See also general parameters of all function blocks.