SystemAir Sense SNX, Installation,Operation And Maintenance Instruction, Page: 13 / 28

13
Fans
Both, supply and extract, fans have external rotor motors
of EC type which are steplessly controlled individually by
setting the control signal to a fixed value. Fans are set to
preconfigurated 3 steps (minimum, medium, nominal)
with boost setpoint. All 3 steps are possible to be
reconfigured depending on the programming of the week
schedule. The motor bearings are life time lubricated and
maintenance free. It is possible to remove the fans for
cleaning.
Filters
Due to geometry of the product and optimization of the
internal airflow, the product consists of three filters. Out of
those one is supply air panel filter with filter quality ePM1
60% (F7). The other two are symmetrically positioned
extract air bag filters with filter quality ePM10 60% (M5).
The filters need to be replaced when polluted either
with maximum pressure drop on supply filter or within
one year, whichever happens first. The HMI display will
show alarm when this happens. New sets of filters or
higher quality filters can be acquired from your installer or
wholesaler.
Heat exchanger
Units are equipped with a counter flow heat exchanger
and a by-pass damper. The operation of the bypass
damper is automatic and depends on the set temperature
or if deicing is in operation. The heat exchanger is
removable for cleaning and maintenance.
Electrical heater (optional)
In air handling units with built in electrical preheater
the heating rods are located between the supply air
fan and heat exchanger in the airflow direction. In units
with built in electrical reheater the heating rods are
located between heat exchanger and supply air grille in
the airflow direction. The material is stainless steel. The
electrical heating battery has both automatic and manual
overheating protection. The manual overheat protection
is reset by pushing the red button on top of the electrical
heater frame. The power demand of the electric heating
coil is controlled by the main regulator, which controls
the heat steplessly by a TTC triac control according to the
selected control function that is set in the control panel.
Pressure sensors
Two pressure sensors are installed, each of the sensors
has two functions. One function (A1) is to measure
the differential pressure over the inlet cone of the fan
impellers to maintain the airflow at constant level (CAV
function as standard). The other function (A2) is to
measure the dynamic differential pressure over the supply
6. Commissioning
6.1 Description of internal components
air filter so that when the pressure drop reaches the set
value, an alarm is triggered in the main regulator, which
indicates that the filter needs to be replaced.
ODA
EHA
ETA
SUP
A2
B3
M3
B1
B2
B5
B4
M2
M1
A1
FS1 FS2+FS3
HE2
DB
HE1
B6+CO 2
CHE
Temperature sensors
Four temperature sensors (NTC 10K) are included in the
unit from factory as standard. Additional two sensors
come in case preheater is selected or CO
2
sensor is added.
The sensors are as follows:
• (B1) Outdoor air temperature sensor
• (B2) Supply air temperature sensor
• (B3) Extract air temperature sensor
• (B4) Exhaust air temperature sensor
• (B5) Electrical preheater limiting sensor (options E01,
E02, EE1, EE2)
• (B6) Room temperature sensor (optional only with CO
2
sensor)
CO
2
sensor (accessory)
CO
2
sensors are used mainly for demand-controlled
ventilation to prevent energy losses from over-ventilation
while maintaining indoor air quality. Considering the
installation of the product, positioning of the sensor will
always be more than 2m above the floor.
Should the costumer want to instal wall sensor, they can
connect it to controller inside electric cabinet on their
own.
Free cooling
This function is used during the warm period to save
energy by using cold outdoor air, e.g. during nighttime, to
cool down the building and thereby reducing the need for
cooling during the day time.
Activation of the function occurs, when
•
Outside air (TOa) is sufficiently low compared to the
apartment temperature (extract or room),
• and apartment temperature is above its actual
se configurable hysteresis,
• and outside temperature is above set minimum limit
•
and free cooling is configured.
For deactivation a hysteresis of 2K (fix) is used. During
activation, the operating mode is set to Comfort and
kept there until one of the activation criteria is no longer
fulfilled. In case of cascade control, the actual room
temperature setpoint (depending on the operating