Remak VCS Installation And Operating Instructions Manual page 16

Control and Protection Functions
Humidification
Humidification control can be ensured by two methods.
Depending on the technology used, control for the required
humidity can be performed by the VCS control unit or by an
autonomous control (e.g., integrated into the humidifier).
In the first case, humidity control is ensured by the VCS control
unit. Settings of humidity set-points and control parameters
are included in the VCS control unit. The same applies for
dehumidification. Thus, full accord of dehumidification and
humidification control is ensured and unsuitable settings of
set-points cannot be made. Furthermore, all the necessary
parameters and information can be found in the control
unit controllers. The control unit sends the start command,
the request for humidification output to the humidifier, and
monitors humidifier failures.
If autonomous control is used, the control unit sends infor-
mation on the air-handling unit operation to the humidifier.
In this case, control for the desired humidity is fully ensured
autonomously by a specific humidifier. The control unit has
no information about the state or output of the humidifier.
Dehumidification
Air dehumidification is ensured by water or direct cooling.
In case of dehumidification, after-heating is ensured by the
heater, which is situated after the cooler. The control unit evalu-
ates the control signal for the air cooler and heater depending
on the room sensors and the required humidity selected by
the user. The humidity in the room can be set from 20% to
95%. If the air-handling unit is equipped with a water cooler or
a condensing unit with an inverter, the humidification process
can be controlled using 0–10 V (2–10 V) step-less control. If
the air-handling unit is equipped with a one-stage or a two-
sage condensing unit, the humidification process is controlled
using step control. When cooling is active due to a request for
dehumidification, air after-heating is allowed (exceptionally)
using the heater situated after the cooler.
If the request for heating is increased above 90 %, the request
for dehumidification cooling is gradually reduced until the
required inlet air temperature, respectively zero value of the
request for cooling (at 100 % request for heating), is achieved
– temperature control is prioritised to humidification.
Auxiliary Control Functions
Pre-heating function
Pre-heating is switched ON/OFF depending on the pre-set
outdoor temperature value (pre-set 5 °C).
The electric pre-heater (EO) is switched using a contactor. It
is controlled according to the pre-set (required) temperature
and compared with the temperature behind the preheater
(measured by the NS 120 sensor). If the air-handling unit is
switched off when the EO pre-heater is active, run-down of
the fans will be performed. Failures are evaluated similarly as
with EO heaters but the system is not shut down.
Water pre-heating is controlled by switching the pump (not
included in the REMAK delivery) depending on the request for
pre-heating. Antifreeze protection is ensured by a temperature
sensor (NS130R) situated in the water heat exchanger return
line. If the water temperature in the water heat exchanger's
return line drops below the pre-set value, the freezing alarm
14
will be activated, including safety functions, and the air-
handling unit will be stopped.
Auxiliary After-Heating Function with EOS
This function is applied when the main heater output is not
sufficient (e.g. when water heating is shut down during tran-
sition seasons, etc.) It is possible to restrict the maximum
electric after-heater output for each output stage. Thus
correct cooling of the heating rods is ensured (see the Data
Points). The electric after-heating function can also work as
an independent sequence with its own settings of required
temperatures. The electric after-heating function is disabled
in the following cases:
n When night chilling is active
n During temperature start-up
Heating Water Source Switching
If this auxiliary function is active and the controller detects the
need for heating water (request for air heating), the output
for the heating water source (boiler) will be switched on – if
the device is started in advance before the fans have been
switched on. This function will only be applied if the outdoor
temperature is higher than the pre-set value (factory settings:
15 °C) otherwise the output is switched on permanently. Cor-
rect operation of the assembly must be ensured by suitable
settings of the device start-up sequence parameters. To enable
the heating water source switching function's correct opera-
tion, the outdoor temperature sensor must be installed so it
will be able to read the actual outdoor temperature.
Figure 12 – Actual set-points with compensation (shift)
Control signal for controller
heating
H shift
TH1 ......Basic set-point of the required temperature for heating – upper heating limit
TH2 ......Actual/current set-point of the required temperature for heating – upper heating limit = (TH1 - shift H)
TC1 ......Basic set–point of the required temperature for heating – upper cooling limit
TC2 ......Actual/current set-point of the required temperature for heating – upper cooling limit = (TH1 -shift C)
H shift for heating set-points
(A negative shift causes a reduction in the required temperature for heating.)
C shift for cooling set-points
(A negative shift causes a reduction in the required temperature for cooling.)
Figure 13 – Set-Point Compensation (Shift)
Description and Settings
delta T (K)
Heating compensation settings Cooling compensation settings
T3 .....Starting point for heating compensation
T4 .....End point for heating compensation
c ........Max. compensation value (delta T)
x.........Actual outdoor temperature
y.........Required heating set-point shift
cooling
Room set-point
C shift
Outdoor temperature (°C)
T1 .....Starting point for cooling compensation
T2 .....End point for cooling compensation
C ........Max. compensation value (delta T)
X ........Actual outdoor temperature
Y ........Required cooling set-point shift