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Boiler functions
5.2
Lag/lead sequence control
The boilers are released depending on the configuration:
4
Co1, Co2* -> Fb00 = OFF: Boiler released according to the position of the mode selector
switch
4
Co1, Co2* -> Fb00 = ON: Boiler 1 is not released if binary input BE17 is closed, pro-
vided Boiler 1 is not locked by the mode switch.
Boiler 2* is released if binary input BE16 is closed, provided Boiler 2 is not locked by the
mode switch.
Function
Release of boiler K1, 2
5.2.1 Control without sensor VFg
The Burner activation independent from sensor VFg function allows the boiler to be switched
on independently from sensor VFg, i.e. exclusively according to boiler sensors VF1 and VF2.
Other functions which have an effect on the lag and lead sequence control of the boiler in
two-boiler systems do not affect the boiler which works independently any more.
On activating the Continuous running of pump function, the boiler pumps react like the pumps
of master controller in normal systems.
Functions
Burner activation not dependent on
sensor VFg
Continuous running of pump
5.2.2 Outdoor temperature-dependent sequence
If the outdoor temperature is above the limit entered in Temperature t
just the lead boiler always remains in operation. The lag boiler is not even activated when the
maximum capacity of the lead boiler is insufficient to achieve an increased flow temperature.
The lag boiler is first released when the outdoor temperature is lower than the limit entered in
Temperature t
for releasing sequence after t = 2 x Lockout time .
A
The limit entered in Temperature t
short-term demand above the limit can be compensated for without any loss in comfort by pro-
longing the operating time of the lead boiler. This depends on the performance of the lead
boiler.
34
EB 5474 EN
WE
Configuration
OFF
Co1, Co2* -> Fb00
* Only in systems Anl 4 to 7
WE
Configuration
OFF
Co5 -> Fb20 = ON
OFF
Co5 -> Fb14
for releasing sequence must be selected to ensure that a
A
for releasing sequence,
A
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