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Siemens Building Technologies Heat-pump controller for wall mounting ACR12.481 CE1N3577en
HVAC Products 27.05.2004
If no external sensor is connected and the terminals B2 and M are short-circuited, then
the internal sensor is used automatically.
Setpoints
For comfort operation, the set-points can be defined in the parameter mode. The
heating set-point is normally set to 21 °C and the cooling set-point to 23 °C. The room
user can adjust the set-points within the limits defined by P13 (maximum ± 6 K). This
produces a maximum set-point range of the default set-points of 15...27 °C in heating
operation and 17...29 °C in cooling operation. The neutral zone remains constant at 2 K
in this example (difference between cooling and heating set-point).
For economy operation, the set-points are fixed at 14 °C for heating and 30 °C for
cooling and cannot be changed with the room units.
However if the economy operation is defined as the normal mode and not as the re-
duced mode (P01 =1) then the offset shift is active for the economy set-points. This
produces a set-point range of 8…20°C for heating and 24…36°C for cooling operation
with P13 set to 6K (the default). The neutral zone remains constant at 16K.
For standby operation, the set-point of the controller is permanently set to 8°C heat-
ing. Adjustments are prohibited, due to the regulations of some countries. Cooling op-
eration is not possible.
Control sequences
Q
K
X
p
X
p
Q
H
W
K
3575D01
YCYC
Y [%]
80
50
X
dz
50% 50%
W
H
100
This diagram shows how the compressor output (YC) is switched when the changeover
between heating and cooling happens automatically. If only heating or only cooling is
allowed, then only the left half of the curve (for heating) or the right half (for cooling) is
valid.
Note that that any time the compressor is switched off it stays off for at least 3 minutes.
Q
K
Q
H
W
K
3575D02
YR
Y [%]
80
50
X
dz
W
H
100
This diagram shows how the output for the reversing valve (YR) is switched when the
change-over between heating and cooling happens automatically.
Compressor
Reversing valve