Data Sheet for Product

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Siemens Building Technologies Heat-pump controller for wall mounting ACR12.481 CE1N3577en
HVAC Products 27.05.2004
Use
For controlling the room temperature in individual rooms and zones which are heated
and cooled with standalone heat-pumps. The controllers are suited for single mode
heat-pumps as well as for heat-pumps with a reversing valve or with an electric heater.
This is achieved by managing the following equipment:
• a 3-speed fan
• a compressor
• a reversing valve or an electric heater
Functions
• Changeover between heating and cooling operation automatically or manually.
• Changeover of operating mode with window contact, occupancy detector or standby
button
• Control of 3 fan speeds automatically or manually.
• Output for an external relay for the compressor.
• Output for the reversing valve or for an external relay for the electric heater.
Type summary
Application Operating panel Type reference
Heat-pump with reversing valve or
electric heater
With display
ACR12.481/ALG
Cable sensor for return air temperature
QAH11.1
Ordering
When ordering, please specify the type reference as shown in the „Type summary“.
Technical design
The room temperature is measured by an in-built sensor (an external return air sensor
is also possible) and compared to the actual set-point. According to the resulting devia-
tion, the processor switches the compressor on or off and controls the reversing valve
or the electric heater. At the same time, the optimum fan speed is automatically se-
lected if the fan speed selector switch of the controller is set to “AUTO“.
The user can choose between P (proportional) and PI (proportional/integral) control.
These and other settings can be made on the device by setting the corresponding pa-
rameters.
The P (proportional) bands for the heating and cooling sequences can be set sepa-
rately between 2 K and 4 K (see parameters P05 and P06).
The integral action time I (integral) is 5 minutes (if parameter P07 = 1).
Temperature Sensors
There are two possible sensors for measuring the actual temperature:
• Sensor inside the controller for measuring the room temperature
• External return air sensor