5:10 (16), 0-004-7516-1 (GB)
TAC AB, 1999-08-18
TAC Xenta 102 Handbook
Functional description
5.3
More about functions
5.3.1 Air flow control
The air flow is controlled by an external air flow controller, for
example Belimo™ VAV-Compact. The air flow controller gets
a setpoint from the VAV controller.
VAV controller
Type:
P I
Gain:
0-32,75; default value: 25
I-time:
0-60 minutes; default 15 minutes
Dead band:
0,2 °C
Control interval:
60 s
Air flow setpoints
Either one of the output Y1 (0–10 V), or nvoFlowSetpoint, which
represent the flow in per cent, can be used for the setpoint.
nvoFlowControlPt, is the desired flow in l/s.
Air flow monitoring
TAC Xenta 102 receives the current air flow values from the
air flow controller, by means of input Z1 (0–10 V) or nviBoxFlow.
The controller uses the air flow measurement to monitor devia-
tions. Current air flow can be read by means of the network vari-
able nvoBoxFlow. The above also applies to the slave mode.
Air flow limits
Air flow is limited in comfort and standby mode. The maximum
flow limit nciMaxFlow is used during normal operation. The mini-
mum flow limit nciMinFlowHeat is used when the electric heating
coil is enabled and there is no fan. If radiators are used or the
electric heating coil is on and a fan is used, then nciMinFlow is
used instead. The controller uses the minimum flow limit nciMin-
FlowStand in standby mode.
Nominal air flow
The configuration parameter nciNomFlow defines the nominal
flow through the VAV box. Both the air flow setpoints and
limits depend on the correct value being set in nciNomFlow.