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Siemens
Standard application AHU
CE1P3977en_02
Building Technologies
Functions
01.02.2010
Ensures that the fans are only influenced, if the heating register does not supply
the required output. This function not required when the heating register is suffi-
ciently sized.
Calculation
– Setpoint supply air pressure: 80 Pa (maximum possible setpoint = Setpoint of
the maximum enabled stage + Max forcing, e.g. = 120 Pa).
– Maximum allowable fan compensation (100 % compensation): 40 Pa.
– Controller output: 50 %.
---> New setpoint: 80 Pa – (40 Pa * 50 %) = 60 Pa (Not exactly true, see Fancomp
for exactly calculation!!!, this text is used on several places!!)
The fan stage is reduced by reducing the setpoint. The air volume to be heated at
the heating register becomes smaller and the discharge air temperature increases.
Switching sequence fan clg: Clg-Fan
– Calculated supply air setpoint for cooling register: 24
℃
.
– Dead zone for the fan cooling controller (dead zone): 2 °C.
---> Effective setpoint for the controller = 22 °C – 2 °C = 24 °C.
Ensures that the fans are only influenced, if the cooling register does not supply
the required output. This function not required when the cooling is sufficiently
sized.
Switching sequence fan clg: Fan-Clg
– Calculated supply air setpoint for cooling: 24 �.
– Calculated supply air setpoint for heating register: 22 °C.
– Dead zone for the fan cooling controller (dead zone): 1 °C.
---> Effective setpoint for the controller: 22 °C + 1 °C = 23 °C.
Ensure that fans are influence prior to the start of the cooling register. This function
can also be used if no coolingregister is avalible. You don’t get colder air but you
have better comfort due to that the air volume is increased.
Calculation
– Setpoint supply air pressure: 80 Pa (maximum possible setpoint = Setpoint of
the maximum enabled stage + Max Force, e.g. = 120 Pa).
– Maximum allowable fan compensation (100 % compensation): 40 Pa.
– Controller output: 50 %.
---> New setpoint: 80 Pa + (40 Pa * 50 %) = 100 Pa.
Cooling example
Basis Document Siemens Climatix Control System
BDCX.100820.01GB
Page 65
