13
Manual operation
Actuator-assisted operation
4.3 - Air filters
•
Check if the correct filters have been installed.
•
Check if the filters have been installed correctly.
•
Set pressure switches or filter indicators, if used.
•
Close the inspection door.
For manual operation the damper blades can open via
hexagon-socket-screw key which is mounted on the
actuators.
AHU with control
The unit is supplied as standard with actuator(s).
• Open/closed
•
Spring return
AHU with control
The supply and extract air filters are equipped with a
pressure switch that is configured in series and normally
closed.
AHU with control
The first hot water coil without glycol in air flow direction is
equipped with a frost protection thermostat. This is set to a
cut-out temperature of 5
o
C.
4.4.1.1 - Coils containing glycol
If coils are filled with a water/glycol mixture, this requires
extra attention.
• Glycol can react violently with strong oxidation
solutions.
• When working on the coil, always check which
medium is used. Before adding anything to the heat
exchange medium, always check with the installer.
• Always wear safety glasses, gloves and shoes.
• Do not smoke or use an open flame.
• When sizing the expansion tank take the higher heat
transfer coefficient into account, (± 25% larger).
• Watertight seals are not always tight for water/glycol
mixtures. It is therefore better to use weld/solder
connections.
• Water/glycol causes increased sludge formation.
• Always observe the instructions of the right glycol
manufacturer.
• Check the mixture to ensure that the glycol concen-
tration (by weight) is correct.
4.4.2 - Electric heater
•
Check and/or connect the heater in accordance with
local regulations and the data from the manufacturer.
• Ensure that the terminal strip earth and the inspection
hatch earth have been connected.
• Check for possible condensate/moisture. Condensate
may form in the period before the first start-up of the
AHU as a result of weather change and/or humid air
from the building. Remove all condensate from the
construction components and dry the electrical
components using warm (dry) air (e.g. with a hair
drier).
• Check the connection voltage.
• Check the existing amperage on all phases. The
values must agree with the data on the heater name
plate.
• To ensure safe operation of the heater, it is equipped
with a thermostat with auto reset (70 °C) and and a
high limit thermostat with manual reset (110 °C).
ATTENTION:
• Do not enter the AHU if the electric heater is on.
• The instructions must clearly specify that the fan
must be operating, before the electric heater is
switched on. After the heater has been switched
off, the fan must continue to run for at least five
minutes.
• As not all electric heater stages have variable
control, always ensure that the minimum speed
across the heater is 2 m/s. If all stages have
variable control the air velocity over the element
can go down to 1.5 m/s.
•
The warning label for electrical voltage is attached to
the inspection hatch.
• Ensure that the end position of the damper is the
same as the end position of the actuator so that the
drive lever of the damper is unloaded in the end
position.
4.4 - Heaters
4.4.1 - Hot water coil
•
Check the connections on the dimensional drawing.
•
Ensure that the coil has been fully purged.
• Check connections for leakage.
• Ensure that the frost protection thermostat has been
correctly connected and set up.
• It is possible that the coil is the last or second last
component in the AHU. The frost protection
thermostat must be made accessible by providing a
field-installed inspection hatch in the supply air duct
• Ensure that the heater can supply heat to prevent frost
formation when the fan is started.
•
City water can be used for water coils without any
conditioning.
CAUTION: When the coils are drained, no water must
remain in the circuits to prevent freezing at
temperatures below zero.
