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System-wide functions
7
System-wide functions
7.1
Switchover between summer time and winter time
The controller switches automatically between summer time and winter time. The summer
time is set to begin on the last Sunday in March at 2:00 a.m. and winter time to begin on the
last Sunday in October at 3:00 a.m.
Function
Switchover between summer time and
winter time
7.2
Frost protection
7.2.1 System frost protection
This function is used to protect the heating coil from being damaged by frost. Depending on
the binary input BE3, the system runs or frost protection function is run. If BE3 input makes
contact, the frost protection function starts: the fans are deactivated and the circulation pump
of the heating coil is activated; a 100 % signal is issued at the control output of the heating
coil Y1.
When the frost protection function is active, STOP and the symbol blink on the display.
The frost protection function is also active in manual operation mode.
Function
System frost protection with BE3
7.2.2 Frost protection HRU
The function "Frost protection HRU" makes sure when the system is running that the heat re-
covery unit does not freeze on the outside. If the HRU return air temperature falls below or
alternatively the extract air temperature measured directly at the heat recovery unit falls be-
low the parameter Heat recovery minimum temperature , the frost protection function is
started: the heat recovery unit is released from the sequential operation. The programmed
limit value is used as the set point for an independent temperature control of this unit to make
sure that further cooling off does not occur. The frost protection HRU remains active until the
control signal Y2 for heat recovery has risen to a value of 95 %; directly after that, the se-
quential operation is reactivated. When the frost protection mode for HRU is active, the sym-
bol blinks on the display.
68
EB 5477 EN
WE
Configuration
OFF
Fb16 = ON
WE
Configuration
OFF
Fb15 = ON
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