Data Sheet for Product

4 / 20
Siemens Central apartment unit with consumption data acquisition QAX913 CE1N2740en
Building Technologies 2016-01-30
Product no. Product number Designation
QAX913-9 S55621-H126 Central apartment unit with mounting
instructions
Functions
The central apartment unit manages heating, cooling, ventilation and hot water
control of an apartment with up to 12 rooms.
It also controls air conditioners (split units), lighting and blinds actuating devices
and monitors light actuators, door and window switches as well as smoke, CO,
natural gas and water detectors.
You can record, together with the consumption data interface WRI982, heating /
refrigeration, hot and chilled water, electricity and natural gas, display it on the
QAX913 central apartment unit and forward it via the OZW772 web server to a
service provider.
The QAX913 also serves as an operator and display unit for the apartment.
Specific functions for heating and cooling plants
The central apartment unit forms a heat or cooling demand signal from the col-
lected heating or cooling requests and forwards it to the heat or refrigeration gen-
eration controller.
The heat / refrigeration demand signal can be delivered via the universal relay out-
put (switching) or at the DC 0…10 V output (modulating) of an RRV912 heating
circuit controller or RRV934 multi-controller.
The flow temperature can be controlled via the RRV934 multi-controller. It is regu-
lated with the help of the heat / refrigeration demand signal. Minimum as well as
maximum limitation of the flow temperature setpoint can be provided, based on an
adjustable value. If the temperature request is invalid, flow temperature regulation
becomes inactive and the control elements are closed during Winter operation (no
output). The central apartment unit supports two room groups (e.g. floor heating /
cooling and radiators) that may be controlled independently.
The return temperature can be maintained at a high or low level, based on an ad-
justable value. This prevents, for example, water that is too hot from returning to
heat generation. Return temperature limitation is given priority over flow tempera-
ture limitation. Return temperature limitation acts on the mixing valve for the room
group.
Setpoint limitation limits the heating setpoint to a maximum value and the cooling
setpoint to a minimum value for the entire apartment.
The central apartment unit calculates the mean value and uses it for room tem-
perature control if a room unit and one or 2 room sensors are assigned to a room.
Several heating circuits connected to an RRV912 / RRV918 heating circuit con-
troller can be combined to one room and operated in parallel. In that case, the first
channel ensures the actual room control and, at the same time, controls the other
assigned channels.
Ordering references
Main functions
Heating and cooling
request
Flow temperature
control / limitation
Limitation of the return
temperature
Setpoint limitation
Room unit /
Room temperature
sensor
Parallel operation of
heating circuit
controllers