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Aquarea air / water heat pump – design handbook 07 / 2014
Closed-loop control
Functions | Extensions and external interfaces
Safety functions | External room thermostat
4.2.3 Safety functions
Besides the listed functions, the control system also contains a series of
further internal functions that ensure minimum compressor operation
time, total current limitation, overheating protection for the compressor
and protection functions for extreme operating conditions as well as
other safety features.
Operation with external room thermostat can prevent frequent switch
on-and-off, in that the room temperature is additionally considered for
control of the heat pump. For this purpose, a room thermostat with
two-step controller is needed. Depending on the current room tempera-
ture and adjustable required temperature, either the circuit L/L1 or the
circuit L/L2 will be switched on via a potential-free switch-over contact.
Depending on which operating mode of the Aquarea heat pump is
activated (Heating or Cooling), the heat pump will be activated or de-
activated via the two-step controller. The operating mode of the heat
pump (Heating or Cooling) acts like an internal release. For example,
if the heat pump is in the heating mode, then closing the circuit L/L2
deactivates the heat pump. Only when an internal release exists by
switching over into the Cooling mode, closing the circuit L/L2 actually
leads to activation of the cooling mode.
4.3 Extensions and external interfaces
4.3.1 External
room thermostat
Condition
L / L1
L / L 2
Required temperature < room temperature Circuit is open (Heating off) Circuit is closed (Cooling on)
Required temperature > room temperature Circuit is closed (Heating on) Circuit is open (Cooling off)
Operating mode - heat pump
Heating
Cooling
Note
For exclusive control of the heating mode via the external room
thermostat, only the phases L and L1 are connected to the terminal
strip. This also effects the Aquarea heat pump series without the
cooling mode.
CLOSE
OPEN
N
1 2 3 4 5 6
7 8
9 10 11 12
15 16 17 18
19 20 21
22 23
CLOSE
OPEN
CLOSE
OPEN
N
COOL
L2
L1
HEA
T
N
L
N
13 14
Connection diagram for the control of Aquarea heat pump via an external room thermostat. The room thermostat is connected to
the terminals 9 to 12 of the terminal strip.