Swegon CLASS UNIT Operation & Maintenance Instructions Manual page 21

Constant airflow
Flow control involves operating the air handling unit to
keep the preset airflow constant. The speed of the fans is
automatically regulated to provide correct airflow even if
the filters become clogged, diffusers are blocked, etc. The
exhaust air fan is controlled as a slave. A ratio between
exhaust and supply pressure can be configured in order
to create over, under or balanced pressure. For units with
backward fans, constant airflow can only be selected if
the "constant air kit" has been ordered as an option. The
desired setpoint is preset in (l/s, m³/h).
Setting
Airflow K1/K2/K3
Ratio exhaust /supply
Enable pressure alarm
DP Supply/Exhaust
for pressure alarm
Initialisation airflow
Pressure alarm initia-
lisation
Torque control
The constant torque operating mode allows to vary the
fan speed automatically, to provide a variable airflow for
demand controlled systems. This operating mode can
partially replace the constant pressure control when a
duct pressure sensor hasn't been installed. The exhaust air
fan is controlled as a slave. A ratio between exhaust and
supply pressure can be configured in order to create over,
under or balanced pressure. The desired setpoint is preset
in %. The Torque control mode can be deactivated in the
advanced setup.
Setting
Airflow K1/K2/K3
Ratio exhaust /supply
Operation and maintenance
Range Factory set-
ting
0...max
5...999% 100%
No Yes
Yes
25...999Pa 200Pa
(l/s, m³/h)
No Yes
Yes
Range Factory setting
0...100%
5...999% 100%
instructions – CLASS UNIT TAC5
Demand control
The airflow desired is regulated in response to 0-10 V
input signals from an external sensor, such as a carbon
dioxide or a humidity sensor. The function can be config-
ured with a positive or a negative logic. A ratio between
exhaust and supply pressure can be configured in order to
create over, under or balanced pressure. The desired set-
point is preset in (l/s, m³/h). The "sleep factor" is a lower
operating rate for the unit (due to e.g. low occupancy)
that will be activated by speed "III "
Setting
Vmin
Vmax
m³/h ~Vmin
m³/h ~Vmax
Ratio exhaust /supply
Sleep factor on K3
Enable pressure alarm
DP Supply/Exhaust
for pressure alarm
Initialisation airflow
Pressure alarm initia-
lisation
Constant pressure
The airflow automatically varies to provide constant
pressure in the ducting. The duct pressure is measured by
an external in-duct pressure sensor which is connected
to the control unit's BUS communication or the an ana-
logue 0...10V input. The function can be configured on
supply air, extract air or supply and extract air. The first
two configurations will have the second set of fans be
controlled as a slave. A ratio between exhaust and supply
pressure can be configured in order to create over, under
or balanced pressure. The initialisation will allow for an
automatic calculated pressure setpoint, determined by
the nominal airflow. The "sleep factor" is a lower operat-
ing rate for the unit (due to e.g. low occupancy) that will
be activated by speed "III "
Setting
Control
Ratio exhaust /supply
Sleep factor on K3
Pressure initialisation
Start reference initia-
lisation
Range Factory
setting
0...10V 1,0V
0...10V 10,0V
(l/s, m³/h)
(l/s, m³/h)
5...999% 100%
10...100% 100%
No Yes
Yes
10...999Pa 200Pa
(l/s, m³/h)
No Yes
Yes
Range Factory set-
ting
Supply Supply
Exhaust
Supply+Exhaust
5...999% 100%
10...100% 100%
Via Airflow Airflow
Via Pressure
Yes Yes
No
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