Basic Documentation
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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Night cooling (basic type A) 03.10.2011
21 Night cooling (basic type A)
The purpose of the "Night cooling" function is to precool the room during vacancy
in summer by making use of lower outside temperatures. Cooling energy can thus
be saved during occupancy.
21.1 Activate block
This function can only be activated with basic type A.
In addition, the following conditions must be satisfied:
Both room temperature and outside temperature must be available
Fan must be activated
Night cooling function is disabled by setting the "Precooling time max" to 0 minutes.
Main menu > Commissioning > Settings > .... or
Main menu > Settings > Night cooling >
Operating line Range Factory setting
Outside temperature limit 0...50 °C 12 °C
Room-outside temp delta 0.0...20.0 K 5.0 K
Operating time min 0...720 min 30 min
Precooling time max 0...2880 min 0 min
Speed Speed 1, Speed 2 Speed 1
21.2 Operating principle
Room temperature > ( Comfort heating setpoint plus 1 K)
Outside temperature > outside temperature limit value
(Room temperature minus outside temperature) > Room-outside temp delta
Time until the plant is switched on the next time by the time switch or holiday /
special day program < precooling time max, i.e. precooling time max can be
maintained
Controller must be in operating mode
Economy
Room temperature <
Comfort heating setpoint
Outside temperature < outside temperature limit value
(Room temperature minus outside temperature) > Room-outside temp delta
With these conditions, the minimum operating time of the "Night cooling" function is
observed.
The outside air damper is opened during night cooling (see section 10.5 "Mixed air
dampe
r (basic types A, P)"); the fans are operating as per the set speed. Speed-
controlled fan (control to constant pressure/volumetric flow) operates at "Speed
min". All other aggregates are disabled.
Purpose
Setting values
Switch-on conditions
Switch-off conditions