System Frost Protection - Honeywell SDC Service Manual

Control Functions
NOTE
See also
6.8.8
Function
124
Cancelling switch-off
The switch-off is cancelled when the current outside temperature
drops below the set value by more than 1 K
The summer switch-off function is cancelled:
• in case of an outside sensor defect
• in case frost protection is active
The HEATING LIMIT parameter can be used to assist the
summer switch-off function. This function allows setting non-
heating periods on warm days for each individual heating circuit.
In connection with a second outside sensor, the current averaged
outside temperature is accepted for summer deactivation if the
average value of both sensors is specified during outside sensor
assignment.
Active summer deactivation is represented by a beach umbrella
symbol in the basic display. In case of separate operation of the
heating circuits ("System Parameters" menu, Control Mode
parameter) the symbol is not displayed. If two outside sensors are
connected and they were assigned to different heating circuits,
the symbol is furthermore only displayed if both sensors fulfil the
condition for summer de-activation.
5.2.3 "System Parameters" menu, Pg. 71

System frost protection

To avoid the freezing of the heating system in switch-off mode,
the controller is equipped with electronic frost protection.
Operation without room temperature sensing
If the outside temperature (current value) drops below the set
limit, heating is turned on again. Heating is interrupted if the
outside temperature exceeds the set limit by 1 K.
SDC / DHC
EN2H-0221GE51 R0812