Version
Document
Preliminary 003
Access V4.X Configuration manual
14 (33)
2019-05-13
Configuration: Configuration > Functions > Function activation > Heating/Cooling sequence setup >
Step controller 1 (Step controller 2)
Cooling
Water cooling
Control
When the unit is in running mode the heating valve is controlled by the analogue output and digital
output for pump control and/or signal for start heating.
Pump indication
A feedback from pump can be used, running indication or alarm indication.
DX cooling
Step controller Heating / DX cooling
As alternative or complement to the above mentioned analogue control, heating and cooling can be
activated in steps. The internal signal is then used to activate digital outputs for control of the
heaters/chillers. Up to four heater outputs and three cooler outputs can be configured. There are two
possible modes:
Sequential control
Each output step has individually settable on and off values in percent of the control signal. The number
of steps is equal to the number of heater/chiller groups. Minimum on and off times can be set, i.e. the
minimum time the step has to be inactive or active for a change to occur.
Binary control
The heater power outputs should be binary weighted (1:2:4:8). The number of loads to be controlled is
set. Thereafter the program will automatically calculate the individual Activate levels. Switching
differential and minimum on/off times can be set.
DX cooler modes
DX cooling with room or extract air control
If DX cooling is used in conjunction with room temperature control or extract air temperature control,
there are two Configure alternatives, DX cooling or DX cooling with exchanger control.
DX cooling without exchanger control
When running cascade control, the supply air controller setpoint is normally controlled by the
room/extract air controller output signal.
When DX cooling is activated, the supply air controller setpoint is lowered to five degrees (adjustable)
below the setpoint given by the room/extract air controller. This prevents the DX cooling from being
activated/deactivated too often.
DX cooling with exchanger control