User Manual

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Siemens Central apartment unit with consumption data acquisition QAX913 CE1N2740en
Building Technologies 2016-01-30
Up to 6 SSA955 radiator control actuators can be combined to one room and oper-
ated in parallel.
The first radiator control actuator (master controller) assumes actual room control
plus wireless control of the other assigned radiator control actuators (parallel con-
trollers).
Multiple heating circuits connected to common heat distribution can be controlled
jointly as a zone. The zone valve (3-point) is controlled based on the temperature
measured value from the room unit and / or room temperature sensor installed in
the reference room.
The central apartment unit issues the enable for room group pumps. They can be
either connected to the internal relay output or a relay output of one of the RRV912 /
RRV918 heating circuit controllers or RRV934 multi-controller.
The QAX913 can trigger an antilime function at regular intervals to prevent valve
plugs and pump impellers from seizing during longer off periods. The function en-
sures that the valve actuators extend to the fully open and then to the fully closed
position and that the pumps are activated for short periods of time (valve kick).
Frequency and the time of day the function is performed can be adjusted.
The anti-lime function acts either locally or on plant components connected to the
RRV912 / RRV918 heating circuit controller and also on the wireless SSA955 ra-
diator control actuators.
The room temperature setpoint in Economy mode to heat all rooms is increased
dependent on the composite outside temperature. The transitions are adjustable to
prevent peak loads during changeover, for example, from Economy to Precomfort
or Comfort.
The minimum flow temperature setpoint is raised depending on the composite out-
side air temperature, ensuring a minimum flow temperature in uncontrolled rooms.
The central apartment unit triggers summer operation. Changeover may occur
manually, by date, as per attenuated outside air temperature, via a digital input, or
through active changeover to cooling mode.
The heating circuit valves connected to an RRV912 / RRV918 heating circuit con-
troller have a position of 0% or 100% and the SSA955 radiator control actuators
are driven to the preselected valve positions.
The QAX913 provides hot water control with the help of a specific hot water time
switch.
Hot water is enabled or locked by on the QAX913 or a hot water sensor connected
to a RRV912 / RRV918 / RRV934.
The signal for DHW charging, or changeover, is delivered either via the internal
relay output or the relay output of an RRV912 / RRV918 heating circuit controller or
the multi-controller RRV934. DHW charging can take place via diverting valve /
charging pump and / or an electric immersion heater.
Specific functions for floor cooling
4 cooling setpoints can be preset for each room. A flow refrigeration request is
calculated per room group for primary processing. The room group controller
RRV934 controls the flow temperature depending on the composite outside air
temperature and individually adjustable cooling curve.
QAX913 can override room controllers RRV912, RRV918 and SSA955 in cooling
mode.
Parallel operation of
radiator control
actuators
Zone control
Room group pumps
Antilime function
Outside air
temperature-controlled
night set point
Minimum
flow setpoint
Summer operation
DHW charging /
DHW control
Room temperature
control