6.11 Control functions
6.11.1 System start-up
Usually, all ventilation systems go over to standard operation first after a start-up phase
when a request for operation exists from deactivated state or from manual operation. The
duration of the start-up is determined by the parameter
Pump advance running time for
start-up. Two options exist to suppress the start-up partially or totally:
1. Pump advance running time for start-up = 0
2. When the outdoor temperature is fedforward, the outdoor temperature must be smaller
than the parameter
Start-up mode when the outdoor temperature is smaller
If the ventilation system goes into operation according to the programmed times-of-use, then
the start-up function already starts to run before the time-of-use commences by the time pe-
riod set in
Pump advance running time for start-up. The fans are enabled exactly when the
time-of-use starts.
If, however, the ventilation system is required to run by an external request for operation or
by the operating mode selector switch, the fans are first enabled after a time delay set in
Pump advance running time for start-up.
By enabling the heating coil circulation pump, the control signal Y1 for the heating coil is en-
abled at the same time:
4
Without the temperature sensor F4 in the heating coil return flow, the control output Y1
runs either 100 % control signal or is set to the fixed value under
Control signal limit for
Y1. The Control signal limit for Y1 only has any effect when the start-up function is active.
4
With the temperature sensor F4 the value set under
Return air temperature maximum limit
or Return air temperature maximum limit coordinate 1 is the set point for the warm-up of
the heating coil during the start-up phase. Y1 varies corresponding to the system devia-
tion. The system start-up function is cancelled when the fixed heating coil return air tem-
perature is reached when the operation of the system has been demanded by the operat-
ing mode selector switch or over the binary input.
All other control outputs
−
also the control output Y2 of an independent mixed air tempera-
ture control
−
usually do not run a control signal during the system start-up. The control out-
put Y2 is enabled when the fans are enabled. Before the control output Y3 (cooling coil) can
be enabled, the
Pump advance running time for start-up must be run through a second time.
In the supply air control loop, the
Supply air temperature maximum limit is set at first as the
set point. Within five minutes, this value is led linearly to the current supply air set point.
EB 5477 EN
61
Control functions