Master DHA 160 Notice Technique page 29

A damper should be installed in the wet air duct to enable correct
setting of the reactivation air volume during commissioning.
The exhaust opening should have a coarse wire net.
Reactivation air into the dehumidifier
For reactivation of the dehumidifier an additional air volume is
needed. This air enters the unit along side the process air. As an
option the dehumidifier can be equipped with duct connections
for entering air (DHA 160 Ø125; DHA 250 2xØ80). One of them
can be used for intake of ambient air for reactivation (DHA 250).
The duct should be as short as possible, requires no insulation,
and can slope up or down. In some installations, as an
alternative, the reactivation air can be taken from the installation
plant room, for this alternative no duct connection is needed.
Process and dry air with the dehumidifier installed in the
dehumidified room
When the dehumidifier is installed in the dehumidified room it
would normally take the process air directly from the room
without any duct system. If the process air inlet needs to be
connected to a duct system, the dehumidifier is prepared for
using a plate with duct connections. The dry air outlet would
normally have a duct system designed for distribution of the dry
air in the building. Process and dry air with the dehumidifier
installed outside the dehumidified room
When the dehumidifier is installed in a separate plant room all
inlet and outlet openings are usually ducted.
The dehumidifier takes the process air as ambient air, or as pre-
treated air (cooled/heated), or alternatively as return air from the
dehumidified room. The dry air from the dehumidifier can be
connected for post treatment or ducted back to the dehumidified
room.
Dampers should be installed in the dry and wet air ducts,
enabling correct commissioning of the air volumes.
Duct connection for basement installation
If the dehumidifier should be installed in the basement it is
sometimes desirable to achieve a slight negative pressure in the
basement to prevent odours from penetrating up into the building.
In these circumstances the reactivation air is taken directly from
the basement and the wet air is exhausted out from the
basement. This method of installation will create a small negative
pressure. The other ducts should be installed according to "Duct
connection for permanent installation
Temporary installation
With temporary installations for water damage or building drying,
flexible plastic ducts would normally be used instead of the spiral
duct type. The drying method differs depending on situation and
construction to be dried. The complete room could be
dehumidified, or just the damaged part. For the later option
plastic sheet is used to cover the damaged area, and the dry air
is supplied under the sheet. For both options the wet air must be
exhausted out from the building via flexible duct, or alternatively
connected to the general exhaust ventilation system for the
building.
6. COMMISSIONING
On initial start up, the following steps should be taken in this
order:
A. Ensure that the external isolation switch is isolating the unit
from the mains, or that the power plug is disconnected.
B. Select the OFF position on the main switch (orange) at the
front of the dehumidifier.
C. Open the service panel on the top of the dehumidifier and
ensure no foreign objects are left inside the unit or in the
electrical compartment
D. Make sure the air filter is installed.
E. Rotate the fan impeller by hand and make sure it can move
freely.
F. Ensure that the dry and wet air dampers are open, and that
ducts are clean and free of blockages.
G. Ensure that the mains supply fuse is suitably rated (10A), and
that the fuse is of a slow kind.
H. Connect the dehumidifier to the main electrical supply by
turning the isolation switch to ON, or alternatively connect the
power plug to the socket.
I. Select the MAN position on the operation switch (black) of the
dehumidifier. Switch the main switch (orange) to the ON posi-
tion for 3-4 seconds. Check that the rotor is slowly rotating,
the fans are starting, and that the orange lamp in the main
switch lights up. Turn OFF the dehumidifier.
J. Mount the service panel and ensure it seals properly to the
casing.
K. The dehumidifier is now ready for operation.
L. Start the dehumidifier and check that the unit is operating at
the correct air volumes.
DHA 250
An indication of correct operation is if the ampere meter on
the front of the dehumidifier indicates approximately 6 A.
M. From the factory the dehumidifier is electrically wired in such
a way that when operating in AUTO mode, the controls
operate the complete unit to start or stop. By shifting one
terminal connection in the electrical panel the operation mode
can be altered to operate the fan continuously. The control will
then only operate the heater on /off, depending on the signal
from the humidistat or other external signal.
7. MAINTENANCE
NOTE ! With all maintenance and service of the dehumidifier:
• Switch off the dehumidifier
prior to opening the service panel, allowing the heater to
cool down.
• Disconnect the dehumidifier from main electrical supply
by turning the external switch to the off position or by
pulling out the power plug
The maintenance intervals for the dehumidifier depend on the
surrounding environment and installation site. Recommended
maintenance intervals could therefore differ from one installation
to another. Incorrect maintenance and service may result in
reduced dehumidification capacity.
Filter
The dehumidifier is equipped with one common filter for the
process air and reactivation air. The filter is positioned at the inlet
and will clean the air prior to entering the dehumidifier.
Intervals for cleaning or replacement of the filters will be
determined by the amount of dust and particles in the air at the
installation site.
We recommend that the filter is checked at least once a month,
at least for the first year of a new installation.
Never operate the dehumidifier without the filter, as the rotor can
be damaged by dust.
Rotor
The rotor is maintenance free. However should it be necessary to
clean the rotor careful use of compressed air should be the first
choice. With severe contamination the rotor can be washed with
water.
Cleaning with water is no routine matter, please contact
distributor prior to this procedure.
Check the rotor bearing and the rotor surface once a year.
Electrical motors
The electrical motors are equipped with ball bearings. The
bearings are designed to last the life of the motor and therefore
no maintenance is required.
Check the motors once a year for any abnormal sound.
Heater
The reactivation electric heater does not need maintenance, but
should be checked twice a year for any dust or mechanical
damage to the heating rods. Clean with a soft brush, or vacuum
clean with dust. Gentle use of compressed air is another
alternative.
Rotor drive belt
Check the belt tensioning at regular intervals. Adjust when
needed by moving the tensioning support wheel closer to the
desiccant rotor.
General summary of maintenance intervals
On demand
Every 6th month
Every 12th month
8. TRANSPORTATION
Observe the following for transport or handling of the
dehumidifier:
approximately 15 minutes