Remak VCS Installation And Operating Instructions Manual page 14

Control and Protection Functions
Further re-lighting of the burner is possible once the protec-
tion time of 150 seconds has elapsed. Modular control of
the burner is step-less based on the actual requirement (set
point) within the Min to Max output range of the gas burner.
The bypass damper (if included in the section) is controlled by
a 0-10V signal (the operating range is 2–10 V depending on
the required flue gas temperature (160 °C pre-set). The regulat-
ing damper position controls the air flow coming through the
gas section and bypass section so that a constant flue gas
temperature is maintained. Accordingly:
n when T > T
flue gas flue gas required
(closed = 0 V)
< T
n when T
flue gas flue gas required
(open = 10 V)
Protection and Safety Functions:
The control unit ensures fan run-down to cool down the gas sec-
tions (the pre-set run-out time is 180 s). The gas section tem-
perature is monitored by the ESD3J triple safety thermostat,
which ensures the following protection and safety functions:
n If the temperature exceeds 50 °C, the fans will be switched
on, even if in the STOP mode.
n If the temperature exceeds 80 °C in the Run mode, the
burner will be stopped, the fans switched to the run-down
mode and then the unit STOPPED; if the temperature exceeds
110°C, the burner will be disconnected from the supply volt-
age. If back air draw (chimney effect) occurs during the STOP
mode and the air temperature in front of the gas section rises
above 50 °C, the TH 167 thermostat will close and switch on
the fans, open the inlet and outlet dampers, and thus the gas
section will be cooled down.
n
Fan malfunction – the unit is immediately switched to the
STOP mode without fan run-out (evaluated also during the
STOP mode)
Heating and Cooling using Heat Pump
Two general control options are available for heat pumps.
Control is not fixed to a specific heat pump type. The control
option selection depends on the designer's consideration
and heat pump type. Two control contacts and an analogue
output are used for control.
Option A
The first digital contact is used to define the air temperature
adjustment type – cooling/heating. The second digital contact
is used to define the process activation – off/on. The analogue
output 0..10 V represents the proportion of the request for
heating or cooling.
Option B
The first digital contact is used to define the heating process
– heating off/heating on. The second digital contact is used to
define the cooling process – cooling off/cooling on.
Analogue output 0..10 V represents the proportion of the
request for heating or cooling.
The heat pump control is equipped with an outdoor tempera-
ture-dependent blocking. The blocking alert is only informative
and is not a failure state. The heat pump will be shut down if
the outdoor temperature is equal to or lower than the refer-
12
the bypass damper closes
the bypass damper opens
ence temperature (see the Data Points). The heat pump will be
started if the outdoor temperature is higher than the reference
temperature (with hysteresis of 3 °C). Frequent switching of
the heat pump is eliminated by blocking of the cooling/heating
restart for 120 seconds. The minimum operating time of the
heat pump can also be set. When cooling/heating is required,
the heat pump will be switched on at 20% of the control signal
and switched off at 10% of the control signal (hysteresis of
10%). The low reference signal on the analogue output (0-10V)
can be set in a range from 0% to 50 % of the control signal
(pre-set 30 %, i.e. a 3-10 V control). The unit can be equipped
with a function blocking the air-handling unit operation when
defrosting the heat pump. The shut-off state of the air-handling
unit is indicated on controllers. After the heat pump defrosting
process has been completed, the air-handling unit operation
will automatically be resumed.
Furthermore, it is possible changing behaviour of different
control signals, e.g. AO signal inversion (see Data Points).
Cooling Control
All cooling sources can be disabled depending on the outdoor
temperature. Cooling is not disabled if the outdoor tempera-
ture is higher than the pre-set cooling enable temperature
(pre-set 12 °C).
Water Cooling
It is controlled the same way as water heating. The mixing
set pump is switched depending on the control signal for the
cooling valve. If the air-handling unit is in the Run mode, the
pump will be switched on when the control signal for the cool-
ing valve is higher than 5% and switched off when the control
signal for the cooling valve is lower than 1%.
n
Pump turning for 60 seconds is performed after every 168
hours of pump inactivity..
Direct Cooling
Direct cooling is controlled by switching the condensing unit
output or by step-less control of the inverter condensing unit.
If a single-circuit condensing unit is used, it will be switched on
when 20 % of the control signal is required and switched off at
10 % (10 % hysteresis) of the control signal. If a double-circuit
condensing unit, respectively two single-circuit condensing
units are used, two stages will be switched. The first stage will
be switched on when 20% of the control signal is required and
switched off at 10% (10% hysteresis) of the control signal. The
second stage will be switched on when 70 % of the control
signal is required and switched off at 60 % (10 % hysteresis)
of the control signal. Frequent switching of the single-stage
condensing unit is eliminated by repeated cooling blocking
for a certain time depending on the setting.
To eliminate the simultaneous switching of both stages at
a sudden control signal increase, the timing (duration of the
first stage) is set.
Inverter Cooling Unit
It is controlled using the start enable signal and step-less
compressor output control signal. The minimum operating
time can also be set. The condensing unit will be switched on
when 20 % of the control signal is required and switched off at
10 % (10 % hysteresis) of the control signal. The unit compres-
sor speed is controlled using a 0–10 V control signal.