Siemens RMB795B Basic Documentation page 77

Control Influence on RXB/RXL room controller
function
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 Air damper open to the max position, fan at
purge 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).
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.
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)
Emergency Maximal heating
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.
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.
Free Not supported
cooling
The room controller assumes the function
precooling
Note
Siemens
Building Technologies
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.
Central control unit RMB795B
Function block: "Room group"
Influence on RDG/RDF/RDU room
thermostats
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).
Not supported
The room thermostat assumes the function
Cooling.
Not supported
Not supported
The room thermostat assumes the function
Heating.
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.
Not supported
The room thermostat assumes the function
cooling.
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CE1P3122en
18.01.2012