Remak VCS Installation And Operating Instructions Manual page 63

Illustrative example of an integrated cooling circuit connection
Capacity
control
0...10 V
RKJ
Faults
Unit HP
Mode: Alarm Comp
Heat/Cool
ON/OFF
Main switch
Failure
Filter
T
D
(Cu8 -50)
SV1
Note: The 4-way valve is displayed in the "cooling" position (SV
without power); the E1 heat-exchanger is in evaporator mode.
Function description
Unit start and operating mode (heating/cooling) can be selected by an external signal. The E2 heat exchanger is alternatively
used for heating or cooling of fresh air supplied to the air-conditioned object. The heat potential of the outlet air is always used.
In winter, the outlet air transfers the heat to the E1 heat exchanger. Thus, heat recovery is achieved. The unit works in heat pump
mode. The valve is without power. Cold inlet air is heated in the E2 heat exchanger (condenser).
In summer, fresh air is cooled as needed in the E2 heat exchanger. The SV valve is energized and the 4-way valve is moved to
the opposite position. The E2 heat exchanger now works as an evaporator. Relatively cold outlet air exhausted from the building
effectively cools the E1 heat exchanger (condenser). Surplus heat is transferred out of the building.
Proper functionality of the system is ensured by the control switchboard (RKJ) with the integrated PLC control system. The
application software optimises the unit's operation and protects it against overloading. The heat recovery level can be step-
lessly controlled (0...10V signal) depending on the inlet air temperature TA (behind the E2 heat exchanger). If the maximum
permissible condensation temperature is reached, the output is automatically reduced. The system is also protected against
freezing of the evaporator by an automatically limited lowest evaporation temperature.
If the integrated cooling compressor unit is used in the air handling unit supplied with the VCS, the PLC for controlling the
integrated cooling is usually installed in the VCS and signalled to the Climatix main controller.
Z3
Z4
Header
Filtr
Z2
SG
Z1
SV
HP
HPA
(21/28bar)
4...20 mA
Valve in position
without power
C1
LP
LPA
(1.7/2.7bar)
4...20 mA
Control units VCS
EX1
Legend:
C1 Cooling compressor
SV1 Power valve
SV 4-way valve
SG Sight glass
EX Expansion valves
E1, 2 Evaporator/condenser
Td, Ts Temperature sensors
Z1-4 Back valves
LP Low-pressure pressostat
HP High-pressure safety pressostat
RKJ Unit power and control distribution board
TA Room temperature
T
A
E2
Fresh air
EX2
E1
Relief air
Building wall
63