Condition for change in lag/lead sequence
ON
Co5 -> Fb10 = OFF,
select:
2
5.3.3 Operating hours-dependent change
(Anl 5 and 7)
After a fixed amount of time has elapsed, counting in hours from the time when the last lag/lead
sequence took place (
Time interval for lag/lead sequence change), the other boiler takes on the
role as lead boiler.
The elapsed operating hours since the last change in lag/lead sequence are shown in the InF5
level.
Functions
WE
Configuration
Automatic change in lag/lead sequence
ON
Co5 -> Fb09 = ON
Condition for change in lag/lead sequence
ON
Co5 -> Fb10 = ON
Parameter
WE
Parameter level / Range of values
Time interval for lag/lead sequence change
168 h
PA5 / 1 to 999 h
5.3.4 Change with binary input
(Anl 4 to 7)
The binary input BE4 can be used for the change in lag/lead sequence when the DHW heating
is not being controlled:
4
BE4 = OFF: Boiler 1 as lead boiler
4
BE4 = ON: Boiler 2 as lead boiler
Functions
WE
Configuration
DHW demand – active
ON
Co4 -> Fb00 = OFF
Automatic change in lag/lead sequence
OFF
Co5 -> Fb09 = OFF
Note!
In system Anl 7 the binary input BE4 can be used either for modulation feedback, for an exter-
nal demand for DHW or for an external change in lag/lead sequence.
5.4
Return flow boost
On fulfilling the criteria for activation (–> section 5.1) the return flow control circuit is closed at
the valve RK1/RK2. In the released boiler K1/K2 (see above), the first stage of the boiler and
the boiler pump Pu1/Pu2 is switched on. The water is circulated in the boiler circuit.
The return control circuit is released if the temperature at the sensor RüF1/RüF2 exceeds the
limit entered in
Minimum return flow temperature. The mixing valve opens and release the cor-
EB 5474 EN
37
Boiler functions
