Eliwell EWCM 4120, Manual, Page: 44 / 75

44
DIGITAL FAN CONTROL
Pick-up
On each activation request by the regulator, all of the exchanger fans are activated simultaneously for a time equal to
the value set using parameter Fn13 (pick-up time).
After this time has elapsed, the fans will be piloted at the speed set by the regulator. If, during the pick-up time, the
regulator wants to turn the ventilation off, the fans will be switched off. The pick-up time will be reloaded at the next
start. If Fn13 = 0 the pick-up is disabled.
Activation and deactivation of power steps must respect the activation and release times for resources Fn16 and
Fn17 , which are loaded at activation/release.
The use of the interstep times Fn16 and Fn17 is enabled in the case of a continuous fan and they are loaded during
the instrument switching on and switching off phases. To prevent uncertainty, it is recommended to set the values to 0.
Proportional band regulation : this occurs if bit1 of parameter ST04 equals 0 (this occurs for St04=0 and St04=1).
The operation depends on the parameter ST02 : Cooling mode if St02=1 and Heating mode if St02=0.
If no condensation probe has been allocated (temperature or pressure), the fan ON/OFF switch will be controlled on
request from the compressor in cooling mode or in heating mode if Fn10=1, otherwise if Fn10=0 the fan is always
ON. During the ON phase, the number of fans switched on in respect to the number of those present depends on the
value set at parameter Fn24. If however a condensation probe has been configured, the fan control is by steps as a
function of the condensation probe value.
The regulator activates a certain number of resources (power steps) to reach the Set point configured ( Fn00 ). The
number of resources required is linked to the difference between the value measured by the condensation probe and
the set point; The greater this difference, the greater the number of resources required to reach the set point. The
temperature/pressure interval between application of one power step and the next depends on the proportional
band and the number of resources present.
The fan may be regulated independently from the compressor or at the request of the compressor, depending on
parameter Fn10 (compressor operation on request).