Assortment / System Description

Fan
-
Powered Box
Serial or parallel control strategy for the fan
19
156 | 275 A6V10866237_en--_b_08
Description Name Default value
Supply air VAV maximum air volume flow for cooling VavSuAirFlMaxC 100 [m
3
/h]
Supply air VAV minimum air volume flow for cooling VavSuAirFlMinC 50 [m
3
/h]
Supply air VAV minimum air flow for ventilation VavSuAflMinVnt 0 [m
3
/h]
Fan start speed at the fan powered VAV box FanSttSpdFpb 50 [%]
Fan end speed at the fan powered VAV box FanEndSpdFpb 100 [%]
Maximum fan speed heating FanSpdMaxH 100 [%]
Minimum fan speed heating FanSpdMinH 50 [%]
19.1 Serial or parallel control strategy for the fan
2 different control strategies can be selected for fan operation on the fan
powered box application:
● Serial fan operation: The air volume is only increased if the valve's or
reheater's positioning signal is fully open and the room temperature
exceeds or breaches an additional offset.
● Parallel fan operation: The fan speed is increased in parallel to the valve's
or repeater's positioning signal.
The two strategies are illustrates in the following example using a modulating
fan and one heating and cooling valve. Both strategies can be used in the same
manner for staged fans.
Y Output signal TR Room temperature
SpH Effective heating setpoint SpC Effective cooling setpoint
YH Heating valve YC Cooling valve
FanSpMax
H
Max. fan speed heating FanSpMaxC Max. fan speed cooling
FanSpMinH Min. fan speed heating FanSpMinC Min. fan speed cooling
OfsFanSttH Offset for fan start heating OfsFanSttC Offset for fan start cooling
Q Fan signal
Figure: Example of a serial control strategy using a modulating fan
Parameter settings
Serial