User Manual

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Siemens HVAC central apartment unit with consumption data acquisition QAX903 CE1N2741en
Building Technologies 2016-01-30
The QAX903 delivers detailed error messages to simplify localizing any errors.
They are output as clear-text messages, thus simplifying interpretation of mes-
sages by the user or expert.
Error messages can be used for triggering other events, such as optical or audible
alarms.
The last 10 error messages are saved in history and can be individually retrieved.
The central apartment unit can be reset to the delivery state via an operating line.
Application examples
Y
Y
2741H01
M1
E
E
T T
M1 Room group pump
E Heating circuit
T Room unit and/or
room temperature sensor
Y Heating circuit valve (2-point) or
radiator – control actuator SSA955
U1
M2
B2
T
Y1
T
T
Y2
B3
T
M3
U2
2741H02
M2 - M3 Room group pump
T Room unit and/or
room temperature sensor
Y1 Radiator – control actuator SSA955
Y2 Heating circuit valve (2-point)
B2 - B3 Flow sensor
U1 Mixing valve radiator, DC 0…10 V
U2 Mixing valve floor heating, DC 0…10 V
Error messages
Delivery state
1 room group with room
control
without precontrol
2 room groups with one
flow temperature control
each