Master DHA 250 Instruction Manual
Contents
General safety information..........................................................................................................................4
Applications..................................................................................................................................................5
Method of operation.....................................................................................................................................5
Product description......................................................................................................................................6
Casing........................................................................................................................................................................6
Rotor..........................................................................................................................................................................6
Filter..........................................................................................................................................................................6
Fan for process- and reactivation air.........................................................................................................................6
Heater for reactivation air.........................................................................................................................................6
Electrical panel..........................................................................................................................................................6
Operation options......................................................................................................................................................6
Installation....................................................................................................................................................7
Installation and service access..................................................................................................................................7
Duct connection for permanent installation..............................................................................................................7
Wet air duct out from dehumidifier.......................................................................................................................7
Reactivation air into the dehumidifier..................................................................................................................7
Process and dry air with the dehumidifier installed in the dehumidified room...................................................7
Process and dry air with the dehumidifier installed outside the dehumidified room...........................................7
Duct connection for basement installation................................................................................................................7
T
emporary installation..............................................................................................................................................8
Electrical installation.................................................................................................................................................8
3
Commissioning.............................................................................................................................................9
Maintenance................................................................................................................................................10
Filter........................................................................................................................................................................10
Rotor........................................................................................................................................................................10
Electrical motors.....................................................................................................................................................10
Heater......................................................................................................................................................................10
Rotor drive belt.......................................................................................................................................................10
General summary of maintenance intervals............................................................................................................11
Transportation............................................................................................................................................11
Fault finding...............................................................................................................................................12
Technical data.............................................................................................................................................13
Performance chart...................................................................................................................................................13
Dimensions..............................................................................................................................................................14
Technical data.........................................................................................................................................................14
Noise data...........................................................................................................................................................15
Symbols...............................................................................................................................................................15
Noise path...........................................................................................................................................................15
Noise data................................................................................................................................................................15
Spare parts list............................................................................................................................................16
Electrical wiring.........................................................................................................................................17
Electrical components................................................................................................................................18
Miscellaneous / Notes.................................................................................................................................19
Subject to change without notice DHA 250
General safety information
4
• Anyone operating the DHA 250 should
have access to this manual, and should be
aware of the safety information.
• Only personnel with adequate knowledge of
the dehumidifier should be allowed to operate and service it.
• Only personnel with authorisation for elec-
trical installations are allowed to make repair
of electrical components.
• Repair of electrical components should be
carried out by suitable qualified personnel.
• The dehumidifier must not be installed in
areas where explosion proof equipment is
required.
• Disconnect the dehumidifier from the mains
prior to opening any service panel.
• Prior to servicing the dehumidifier must be
left to cool down for at least 15 minutes after
operation.
• The service panels should remain closed
except when serviceing is carried out.
• The dehumidifier can only be used for dehu-
midification of air at atmospheric pressure.
• Never use the dehumidifier without the
filters as the desiccant rotor can become
contaminated and lose capacity
• Signs and instructions on the dehumidifier
should not be removed or altered.
• This manual should always be accessible and
kept close to the dehumidifier
• All maintenance and control of the dehumid
ifier should be as per the specified schedule.
• Use only genuine spare parts.
.
.
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Subject to change without notice DHA 250
5
Applications
Dehumidifier DHA 250 is of the solid desiccant wheel type designed to dry air of atmospheric pressure. The dehumidifier can be used
for drying air of up to 100 % relative humidity
(RH) with temperatures from -30 ºC to +40 ºC.
The applications are numerous and wide spread.
Below are some examples:
• Controlling humidity levels in production
processes.
• Drying of temperature sensitive products.
• Maintaining correct humidity in storage
areas.
• Protection of equipment sensitive to corro-
sion.
• Controlling humidity levels in museums and
archives.
• Drying after water damage and drying of
buildings during construction.
• Climatic improvements in damp areas.
Method of operation
The dehumidifier operates with two air streams.
A larger air stream to be dehumidified, and a
smaller air stream to exhaust the moisture out of
the desiccant rotor.
Both airstreams are created by one common fan
which pressurises a compartment of the dehumidifier creating two separate airstreams.
The larger air volume, the process air, passes
through the slowly rotating silica gel rotor.
Silica gel is a hygroscopic material adsorbing
water vapour direct from the air. When passing through the rotor the humidity of the air is
reduced, whilst the moisture content of the rotor
material increases. On exiting the rotor the dried
air is introduced into the area, or the process to
be dehumidified. The adsorption process works
in temperatures from -30 ºC to +40 ºC.
The smaller air volume, the reactivation air,
adsorbs the moisture from the silica gel rotor.
This reactivation air first enters a purge sector of
the rotor, thus cooling down the rotor material,
and simultaneously increasing the reactivation
air temperature. The temperature of this preheated air is further increased by an electrical
heater to a temperature of approximately +100
ºC. As the reactivation air passes through the
rotor, in an opposite direction to the dry air, it
will decrease the moisture content of the rotor
material. The reactivation air will leave the
dehumidifier as warm, wet air, which is then
exhausted out from the building.
Subject to change without notice DHA 250
Product description
6
The dehumidifier is designed to meet the
requirements of IEC protective class IP 44:
Casing
The casing is fabricated from stainless steel
2333. The top of the dehumidifier has a top
panel that can be removed for service access to
electrical and mechanical components. All duct
connections to the dehumidifier are designed for
connections to standard size spiral ducts.
Rotor
The dehumidifier has a drying rotor fabricated
from a desiccant material. The rotor has a matrix
of corrugated and flat heat resistant sheets which
houses the Silica Gel desiccant agent. This
matrix creates a large number of axial flutes
through the rotor, which together builds up an
immense surface area for moisture adsorption
in a small volume. The rotor is manufactured
and processed to be able to withstand moisture saturated air without being damaged. This
means that the rotor can be used in conjunction
with a pre-cooling coil. Furthermore the rotor
will not be damaged even if the fan or the heater
for reactivation should fail during operation. The
rotor is incombustible and non flammable.
The slow rotation of the rotor is achieved by an
electrical gear motor and a belt drive. The belt
sits on the outer rim of the rotor and is driven by
a pulley on the drive motor. An adjustable belt
tension device keeps the belt in place and maintains tension to prevent belt slip. Correct opera-
of the drive system, and direction of rotation
tion
can be checked by opening the top panel.
Fan for process- and reactivation
air
The fan is a direct drive radial fan with a single
phase standard motor class IP 54, ISO F. The
fan is accessible for service after removing the
top panel of the dehumidifier.
Heater for reactivation air
The reactivation heater is of the PTC-type
(Positive Temperature Control), which can not
be overheated, and gives the possibility of a
stepless control for 30 - 100 % of the dehumidification capacity. This is achieved by controlling
the wet air volume.
Electrical panel
The electrical panel is located inside the dehumidifier and is accessible through the top panel.
Switches and indications for operation are
mounted at the front of the electrical panel.
Operation options
Using the operation switch on the front side of
the dehumidifier, different running options can
be selected:
0 Dehumidifier not in operation.
1 Dehumidifier in operation mode.
MAN Dehumidifier in continuous
operation.
AUTO Automatic operation by remote
humidistat, or other external
on/off signal.
The centre hub of the rotor is equipped with ball
bearings. The rotor shaft is made from stainless steel. The complete rotor part can easily be
removed and lifted as one piece out from the
casing.
Filter
The dehumidifier has one common filter for
process- and reactivation air.
Subject to change without notice DHA 250
Installation
7
Installation and service access
Dehumidifier DHA 250 is designed for
indoor installation. The dehumidifier should be
installed horizontally.
All components in the dehumidifier are accessible from the top of the unit. For inspection
and service, a space of 400 mm must be left
free above the dehumidifier to accommodate for
servicing of filter, fan and rotor.
When using a mounting plate, the dehumidifier
must be put so that the rotorshaft still is horizontal and the wet air outlet is placed low.
Duct connection for permanent
installation
The dehumidifier can be installed in the room
that should be dehumidified or in a separate
plant room.
To obtain the best performance the outlets from
the fans should be equipped with diffusors.
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 (2 x Ø80). One of them can
be used for intake of ambient air
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.
for reactivation.
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.
Wet air duct out from dehumidifier
The wet air from the dehumidifier should be
exhausted to the outside. The duct should be as
short as possible to minimise the chance of condensation of the wet air. This duct should slope
down slightly to stop any condensed water from
flowing back into the dehumidifier.
If the wet air duct is extremely long, or must be
installed sloping upwards from the dehumidifier,
it should be insulated and have a drainage point
(2 mm) drilled at its lowest position.
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.
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.
Subject to change without notice DHA 250
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