Master DHA 250 User manual

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Subject to change without notice DHA 250
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
Temporary installation..............................................................................................................................................8
Electrical installation.................................................................................................................................................8
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

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Subject to change without notice DHA 250
General safety information
• 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 oper-
ate 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
Applications
Dehumidifier DHA 250 is of the solid des-
iccant wheel type designed to dry air of atmos-
pheric 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 dehu-
midifier 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 pass-
ing 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 pre-
heated 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.

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Product description
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 mois-
ture 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 main-
tains tension to prevent belt slip. Correct opera-
tion of the drive system, and direction of rotation
can be checked by opening the top panel.
The centre hub of the rotor is equipped with ball
bearings. The rotor shaft is made from stain-
less 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.
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 dehumidi-
fication capacity. This is achieved by controlling
the wet air volume.
Electrical panel
The electrical panel is located inside the dehu-
midifier 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.

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Installation
Installation and service access
Dehumidifier DHA 250 is designed for
indoor installation. The dehumidifier should be
installed horizontally.
All components in the dehumidifier are acces-
sible 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 horizon-
tal 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.
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 con-
densation 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.
Reactivation air into the dehumidifier
For reactivation of the dehumidifier an addi-
tional air volume is needed. This air enters the
unit along side the process air. As an option the
dehumidifier can be equipped with duct connec-
tions for entering air (2 x Ø80). One of them can
be used for intake of ambient air for reactivation.
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 usu-
ally ducted.
The dehumidifier takes the process air as ambi-
ent 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.

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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 nega-
tive 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 situa-
tion and construction to be dried. The complete
room could be dehumidified, or just the dam-
aged 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.
Electrical installation
See the electrical wiring diagram on page 17.

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Commissioning
On initial start up, the following steps should be
taken in this order:
1. Ensure that the external isolation switch is
isolating the unit from the mains, or that the
power plug is disconnected.
2. Select the OFF position on the main switch
(orange) at the front of the dehumidifier.
3. Open the service panel on the top of the dehu-
midifier and ensure no foreign objects are left
inside the unit or in the electrical compart-
ment
4. Make sure the air filter is installed.
5. Rotate the fan impeller by hand and make
sure it can move freely.
6. Ensure that the dry and wet air dampers are
open, and that ducts are clean and free of
blockages.
7. Ensure that the mains supply fuse is suitably
rated (10A), and that the fuse is of a slow
kind.
9. Connect the dehumidifier to the main electri-
cal supply by turning the isolation switch to
ON, or alternatively connect the power plug
to the socket.
10. 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.
11. Mount the service panel and ensure it seals
properly to the casing.
12. The dehumidifier is now ready for operation.
13. Start the dehumidifier and check that the unit
is operating at the correct air volumes. An
indication of correct operation is if the ampere
meter on the front of the dehumidifier indi-
cates approximately 6 A.
14. From the factory the dehumidifier is electri-
cally wired in such a way that when operat-
ing 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.
See the electrical wiring diagram on page 17.

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Maintenance
The maintenance intervals for the dehumidifier
depend on the surrounding environment and
installation site. Recommended maintenance
intervals could therefore differ from one instal-
lation 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 heat-
ing 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.
NOTE ! With all maintenance and service of the
dehumidifier:
• Switch off the dehumidifier approximately
15 minutes 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.

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General summary of maintenance intervals
Observe the following for transport or handling
of the dehumidifier:
• Check the dehumidifier on delivery for any
transport damage.
• The dehumidifier should be protected from
rain and snow.
• The dehumidifier should always stand upright
on its feet.
• Transport and lift the dehumidifier by the
two handles on each side of the transportation
box.
Transportation
Filter Rotor Bearing Motors Rotor drive Heater Sealings
On demand √ √
Every 6th month √ √
Every 12th month √ √

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Fault finding
Malfunction Possible cause of trouble Corrective action
None, or reduced dehumidification
capacity
Filter clogged
Electrical heater faulty
Airflow reduced
No rotation of rotor
Internal leakage in unit
Altered air volumes
Altered reactivation temperature
Air leakage
Clean or replace filters
Check fuses
Check openings and dampers
Check belt tensioning
Check springs
Measure and check air volumes
Check reactivation heater
Check panel and casing
Main fuse faulty Fan faulty
Too large air volume
Rotor does not rotate
Reactivation heater faulty
Check fan and motors
Check air volumes and dampers
Check drive motor and drive belt
Check reactivation heater
Dehumidifier does not start No control circuit
Faulty control signal
Fuse for controls faulty
Check control fuses
Check external start/stop signal
Check electrical components
Rotor does not rotate Drive belt is slipping
Drive belt broken or worn
Rotor jammed
Drive motor faulty
Check belt tensioning
Replace drive belt
Check centre shaft, rim of rotor
Replace complete gear motor
No dry- or wet air volume Filter clogged
Fan faulty
Ducts blocked
Clean or replace filters
Check fan, motor and impeller
Check dampers and ducts

Technical data
Performance chart
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CAPACITY DIAGRAM
0
5
10
15
20
0 5 10 15 20
XP (g/kg)
XT (g/kg)
0
5
10
15
20
Temperature rise (oC)
tp=30°C
tp=20°C
tp�10°C
EXAMPLE:
Process air: xp = 9,0 g/kg, tp = +20°C giving
Dry air: xT = 6,1 g/kg, tT = 20+8,5 = 28,5°C

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Dimensions
Technical data
Dehumidification capacity 1,1 kg/h
(at +20 ºC and 60 % RH.
See performance chart for other data)
Dry air flow 290 m3/h
(freeblowing)
Wet air flow 80 m3/h
(freeblowing)
Power supply 1,4 kW
(1 x 230 V, 50 Hz)
Current 6,1 A
(connection fuse: 10 A)
Weight 18 kg
Noise level 61 dB(A)

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Noise data
Noise path
A
Open intake for process
air.
B
Open intake for process
air. Dry air outlet ducted
and air discharged at 2-3
m above floor.
C
Ducted outlet for dry
air. Wet air outlet ducted
with short 90 degree
angle duct.
D
Only dry air and wet air
outlet ducted.
Noise data
E
All outlets completely
ducted.
Correction of K dB at ISO-band No/Centre frequency (Hz)
Noise path LWA 1/64 2/125 3/250 4/500 5/1000 6/2000 7/4000 8/8000
A 65 -26 -14 -10 -10 -9 -3 -9 -15
B 66 -22 -11 -6 -10 -10 -3 -9 -15
C 67 -27 -12 -7 -7 -10 -3 -8 -14
D 67 -27 -13 -7 -10 -10 -3 -8 -14
E 59 -24 -10 -11 -6 -4 -5 -14 -20
Symbols
LWA = Total noise level in dB(A) (rel. 10-12W)
LWAO = Noise power level in octave band dB(A) (rel. 10-12W)
K = Correction for calculation of LWAO (LWAO = LWA + K)
dB(A) = Noise power level at room condition R = 102 Sab

Spare parts list
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Part Technical specification No installed No of recom-
mended spare
parts
Comment
Drive motor Gearmotor 230-240 V 50 Hz 3 rpm
low temp grease
1 1
Belt pulley HTD 5M, Z=20 1
Drive belt 1050-5M-9 1
Fan G2E 160-AS52-132 1
Capacitor 4 µF 400 V 1
Heater PTC HR-AB PH2PA24014711 230 V 1 1
Wet air duct Heat resistant flexcord Ø80 1
Rotor PPS 250 1
Belt tensioning 1
Filter AAF R29 EN779:G3 220 x 330 mm 1 3
Toggle switch 2x1 pol. electric switch 1
Ampere meter RQ48E 10A IP 54 1
Cord H07RNF/3 x 1,5 1
Process air duct con-
nection
2 x Ø80 0 Option

17
Electrical wiring
2 6 4
C
M1
M2
P2
E
1 1 2 2 3 3 4 4 5 5 6 6
3 4
A
h
8 9
1 4 6 2
P1
S2S1
1 2 3 6
230 V 50 Hz
1,4 kW
P3
4 5
Subject to change without notice DHA 250
Name Component S1/S2 On-Off / Man-Auto switch h Runtime meter * HS Humidistat * A Amperemeter P1 Terminal block 7-pin E React. heater M1 Drive motor, rotor C Capacitor P2 Terminal block 4-pin P3 Terminal for humidistat M2 Fan *) Optional
Optional operation method when controlled by humidistat If continuous operation of the fan is requested, and the humidistat HS should control only the reactivation heater, shift wire 2-2 from terminal P1:2 to terminal P1:1 Humidistat Connect humidistat to terminal P3:8-9
Black Brown Blue Yellow / Green

Electrical components
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No Part Mark Type Quantity Manufacturer
1 Gear motor 230 V, 50 Hz, 3 rpm M1 823055BJ 1 Crouzet AB
2 Radial fan, G2E 160-AS52-132 M2 EK259 1 ZIEHL-ebm AB
3 Capacitor, 4 µF 400 V C KO218 1 ZIEHL-ebm AB
4 Toggle switch 2x1-pol. bl/or S1/S2 255036 1 Orbitus Ind.komp.
5 Amperemeter A RQ48E 10A IP54 1 Tälje mätinstrum.
6 Heater, 230 V E PH2PA24014711 1 Victon Ltd.
7Terminal male 7-pin P1 sls 5.08/7B sn or 1 Weidmüller AB
8 Terminal, female 7-pin P1 blz 5.08/7 sn or 1 Weidmüller AB
9 Terminal male 4-pin P2 sls 5.08/4B sn or 1 Weidmüller AB
10 Terminal female 4-pin P2 sls 5.08/4 sn or 1 Weidmüller AB
11 Blind panel, 48 x 48 - 11110 1 Tälje mätinstrum.
12 Blind plug, 22,0-25,5 mm - P208/4 1 OEM Component
13 Cord, H07RNF/3G1.5/3,5m - 2440032 1 OEM Component
14 Runtime meter h *
15 Humidistat plug connection HS *
*) Option