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Siemens
Central control unit RMB795B
CE1P3122en
Building Technologies
Function block: "Room group"
18.01.2012
Control
function
Influence on RXB/RXL room controller
Influence on RDG/RDF/RDU room
thermostats
Cooling
Cooling only
Individual room controllers can only cool. The heating sequences on the individual room
controllers are locked.
Note: This superposed control function is relevant to 4-pipe systems only. It does not impact the
H/C changeover in a 2-pipe system!
Night
purge
Air damper open to the max position, fan at
high speed
The room controller must be in Economy room
operating mode. It cools using outside air from
the open outside air damper and active fan to the
Comfort cooling setpoint. The outside air
temperature must be less than the room
temperature (hysteresis).
Air damper open to max. position
This function may only be used with VAV
thermostats. The VAV thermostat must be
in Economy room operating mode. It cools
using outside air from the open outside air
damper to the Comfort cooling setpoint.
The outside air temperature must be less
than the room temperature (hysteresis).
Precooling
Maximum cooling
The room controller must be in Economy or
Precomfort
room operating mode. It cools prior to
actual occupancy using the fan and cooling coil
to the Comfort cooling setpoint.
Not supported
The room thermostat assumes the function
Cooling
.
Off
Neither cooling nor heating
Temperature control for the individual room controllers is completely shut down. Safety
functions (e. g. frost) are to some extent out of service. All other functions as well as
communication remain active.
Test
Not supported
(S-mode function)
Not supported
Emergency
heating
Maximal heating
The room controller switches on all installed
heating aggregates as soon as the room
temperature drops below the frost limit value
independent of the active operating mode.
Heating ends as soon as the room temperature
once again exceeds the Protection heating
setpoint.
Not supported
The room thermostat assumes the function
Heating
.
Fan only
Air damper open to the max position, fan at
high speed
The room controller must be in Economy or
Precomfort
room operating mode. It only
operates the fan or air damper to achieve a
maximum air exchange. Temperature control is
switched off; heating and cooling sequences on
the room controller are locked.
Air damper open to the max position,
fan at high speed
The VAV thermostat opens the air damper
to achieve a maximum air exchange. The
fancoil thermostat only operates the fan at
the maximum speed. Temperature control
is switched off; heating and cooling
sequences on the VAV thermostat are
locked.
Free
cooling
Not supported
The room controller assumes the function
precooling
Not supported
The room thermostat assumes the function
cooling.
The following applies to RXB/RXL room controllers: The sequence Heating
Auto
Cooling must be selected if the control function specification calls for changing
over from one control function (e. g. heating) to another control function (e. g.
cooling).
This does not apply to RDG/RDF/RDU.
Note
