FCU 500, FCU 505 · Edition 02.17 27
Air control
5 Air control
Acting as the furnace protective system, the FCU 500
assumes the task of central air control on a furnace. It
controls and monitors the required air volume for start-
up, during operation and after the furnace has been
shut down. The fan is activated by the FCU for this pur-
pose. The static air pressure and the air volume for pre-
purge can be monitored by pressure switches.
VAS
M
PZL PZH PZ
PZL PDZ
TE
BCU 580..F3
FCU 500..F0
µC
P
DG DG DG
VAS
VAS
VAGVAS
VAS
VR..L
VR..L
DG DG
DG
min
DG
max
49 15 131450
45
47 4858
>750°
p
u
/2
ϑ
1
46
2
3
DL
min
DL
Purge
BCU 580..F3
VAGVAS
VAS
M
PZL PDZ
BCU 580..F3
FCU 500..F0
µC
P
VR..L
VR..L
DG DG
49 15 131450
45
47 4858
>750°
ϑ
1
46
2
3
DL
min
DL
Purge
BCU 580..F3
M
STM
The capacity control function provided by the FCU 500..
F1/F2 and FCU 505..F1/F2 allows an additional cen-
tral actuator or a frequency-controlled fan to be con-
trolled and monitored. While the furnace is starting up,
the capacity control system controls and monitors the
required air volumes for purging and for starting the
burners. During operation, the FCU enables the exter-
nal temperature control system for capacity control.
To Next Page
