6.11.4 Enabling fan speed 2
The fan speed 2 is controlled via the binary output BA3. It is enabled either:
4
by
Times-of-use for fan speed 2,
4
by an external demand for fan speed 2,
4
dependent on the air quality,
4
for room temperature control or room temperature cascade control dependent on the
room temperature and/or when Fb7 is activated dependent on the room humidity.
After fan speed 2 has been demanded when the system is in stand-by, first fan speed 1 is
enabled; speed 2 is only enabled after the
Delay time has elapsed. When the speed 2 is
switched back to speed 1, the fans are switched off; speed 1 is only enabled after the
Delay
time has elapsed.
The
Delay time is still taken into account even if the fans are activated in manual operation mode.
Functions
WE
Configuration
Two-speed fans over BA2/BA3
OFF
0 sec
Fb11 = ON
BA2 = BA3 = ON
BA2 = OFF, BA3 = ON
Delay time / 0 to 60 sec
The following applies:
(1) BA2 = BA3 = ON
(2) BA2 = OFF, BA3 = ON
Note!
If the outdoor air/extract air damper should additionally be controlled over BA2, it will be
necessary to determine that BA2 also remains activated when fan speed 2 is in operation.
Activating the fan speed dependent on the air quality
If the air quality falls below the
Air quality set point, the operation of fan speed 2 is de-
manded. The fans are switched back to fan speed 1 when the air quality has risen to a value
greater than
Air quality set point + Differential gap of speed 2 –> 1, provided that the time
schedule for “Fan speed 2” or the external demand for fan speed 2 do not require the oppo-
site.
EB 5477 EN
63
Control functions
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