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Siemens
RXB (KNX) application library
FNC Description of functions for FC-10, FC-11, FC-12
CM110385en_05
Building Technologies
Control sequences
28 Feb 2009
8.2
Fan coils with damper control
In FNC20, a single damper actuator is used for control of both heating and cooling.
8.2.1
Four-pipe fan coils with damper control (FNC20)
In application FNC20, which uses a damper instead of a valve for modulating control of
the room temperature, a constant volume of water flows through the two heat
exchangers. Depending on the demand, the air flow is guided either through the
heating coil or through the cooling coil, causing a change in the resulting mixed air
temperature.
10
38
5D
12
100
TR [°C]
Y [%]
SpH SpC
YM
H
C
0
N
Y Damper
position
TR Room
temperature
SpH
Effective heating setpoint
SpC Effective
cooling
setpoint
H Heating
sequence
N
Dead band (recirculated air)
C Cooling
sequence
YM Damper
actuator
The heat-exchanger configuration may call for asymmetric runtimes for heating and
cooling; these can be set individually. At the mid-point where the air flow switches from
heating to cooling, the time period associated with the mechanical dead band can also
be preset.
Select
Sequences
.
ETS3
Professional