Munters ML180 User manual

190TGB-1034 © Munters Europe AB 2002
ML/MLT
180-350
User’s Manual
Desiccant Dehumidifier
ML180-MLT350
Effective for units manufactured from week 46, 2002

ML180-MLT350 Dehumidifiers
190TGB-1034-A02.10 Contents 3
Contents
Important user information.............................4
1 Introduction
1.1 General..........................................................5
1.2 About this manual..........................................5
1.3 Safety and Cautions ......................................5
1.4 Markings ........................................................6
1.5 Operator stations ...........................................6
1.6 Fault indications.............................................6
2 Installation
2.1 General..........................................................7
2.2 Safety.............................................................7
2.3 Moving the Equipment...................................8
2.4 Packaging and Delivery Inspection................8
2.5 Storing the Equipment...................................8
2.6 Location Requirements..................................9
2.7 Process and Dry Air Connections..................9
2.8 Ducting.........................................................10
2.8.1 General recommendations ...............10
2.8.2 Ductwork for Outdoor Air Inlet ..........11
2.8.3 Ductwork for Wet Air Outlet..............11
2.9 Precaution for unit using LI desiccant rotor .12
2.10Installation Examples...................................13
2.10.1 Closed System .................................13
2.10.2 Open System....................................13
2.11Electrical Connections.................................14
2.11.1 Mains Supply....................................14
2.12External Humidistat......................................14
2.12.1 Location Requirements.....................14
2.12.2 Electrical Specifications....................14
2.13Pre-Start settings.........................................15
2.13.1 One-step humidistat .........................15
2.14Pre-Start Checks .........................................15
2.15Airflow Check and Adjustment.....................16
2.15.1 General.............................................16
3 Operation
3.1 General........................................................18
3.2 Safety...........................................................18
3.3 Emergency stop...........................................18
3.4 Pre-Start Checks .........................................18
3.5 Operating the unit........................................18
3.5.1 Manual Mode....................................18
3.5.2 Automatic Mode - Humidistat ...........19
3.5.3 Automatic Mode - RH98...................19
3.6 Control Panel...............................................20
4 Maintenance
4.1 General........................................................21
4.2 Safety...........................................................21
4.3 Maintenance Schedule ................................21
5 Fault Finding
5.1 General........................................................23
5.2 Safety...........................................................23
5.3 Exchangeability............................................23
5.4 Fault localization..........................................23
6 Product Design Information
6.1 Product Description......................................25
6.2 Principal of operation...................................25
6.3 Dimensions and service space....................26
6.4 Capacity Diagrams.......................................27
6.5 Technical Specifications...............................28
6.6 Unit’s main components...............................29
7 Appendix 1- Options
7.1 General........................................................30
7.2 Configuration alternatives............................30
7.3 Running Time meter ....................................30
7.4 RH98............................................................30
7.4.1 General.............................................30
7.4.2 Display / change setpoint of relative
humidity ............................................31
7.4.3 Display / change of other
parameters .......................................31
7.4.4 Process related alarms.....................32

ML180-MLT350 Dehumidifiers
4Important user information 190TGB-1034-A
Important user information
Intended use of equipment
Munters dehumidifiers are intended to be used
for the dehumidification of air. All other uses of
the equipment, or use which is contrary to the
instructions given in this manual, can cause
personal injury and/or machine damage.
Warranty and obligations
The warranty period is 12 months from the date
the equipment left our factory unless otherwise
advised in writing. The warranty is limited to a free
exchange complete with free freight, of faulty
units or components which have failed as a result
of faulty quality or defects in manufacture.
Munters guarantees that the delivered unit has
undergone rigid testing to ensure that the
specifications stated here are fulfilled. All claims
on warranty must verify that the fault has occurred
within the guarantee period, plus that the unit has
been used within its operating range as stated in
the specification. All claims must include the unit
type and manufacturing number. This data is to be
found stamped on the unit identification plate,
see Section Markings for location.
Note
The contents of this publication can be changed
without prior notice.
This publication contains information which is
protected by copyright laws. No part of this
publication may be reproduced, stored in a system
for information retrieval or be transmitted in any
form, in any manner without Munters’ written
consent.
Please send any comments regarding the content
of this publication to:
Munters Europe AB
Dehumidification Division
Technical Publications
PO Box 434
SE-191 24 Sollentuna
Sweden
Tel.: [phone]
Fax: [phone]
© Munters Europe AB 2002
Safety
In this publication hazardous activities are
indicated and preceded by the common hazard
symbol.
WARNING! is used in this
publication to indicate a possible
danger that could lead to personal
injury. An instruction is normally
given, followed by a short
explanation plus the possible effect if
the instruction is not followed.
CAUTION! is used in this
publication to indicate a possible
danger that could lead to damage to
the machine or other equipment
and/or cause environmental
damage. An instruction is normally
given, followed by a short
explanation plus the possible
environmental effect if the
instruction is not followed.
NOTE! Used to accentuate supplementary
information that is required for problem-
free use or optimal use of the unit.
Conformity with directives and standards
Munters dehumidifiers are designed and manufactured
by an EN-ISO 9001 accredited development and
manufacturing organization. The unit conforms with
the specifications in the Machinery Directive
98/37/EEC, the Low Voltage Directive 73/23/EEC as
amended by Directive 93/68/EEC and the EMC
Directive 89/336/EEC as amended by Directives
92/31/EEC and 93/68/EEC. The standards applied
are listed in the EC Declaration of Conformity.

ML180-MLT350 Dehumidifiers
190TGB-1034-A 1 Introduction 5
1 Introduction
1.1 General
Munters dehumidifiers are designed to efficiently dehumidify air.
Munters has a wide range of dehumidifiers that have design parameters
applicable for different usages and applications. Please contact your
nearest Munters office if you have any doubt or questions regarding the
actual installation.
For product data information, see chapter 6, Product Design Information.
1.2 About this manual
This manual is written for the user of the dehumidifier and describes
the installation, operation, maintenance and basic fault finding.
The information structure of the manual is built on numbered chapters
and sections. Contents (page 3) gives a quick overview. The different
chapters can be used separately to serve their purpose. Figures and
tables are numbered in accordance with the actual chapter, e.g. figure
1-3 is picture number 3 and is found in chapter 1.
The goal of the manual is to provide the necessary information for the
user to understand the unit’s construction and function, and as to serve
as a guide during installation, operation, maintenance and basic fault
finding that generally can be carried out before contacting Munters
Product Service.
1.3 Safety and Cautions
The contents of this manual include suggested best working practices
and procedures. These are issued for guidance only, they do not take
precedence over the individual responsibility and/or local safety
regulations. During installation and operation of this equipment it is
always each individual person’s responsibility to consider:
• Their own and others’ personal safety.
• The safety of the unit through correct us of the equipment in
accordance with the descriptions and instructions given in this
manual.
Every care has been taken in the design and manufacture of the ML-
Series dehumidifiers to ensure that they meet the safety requirements
of the directives and standards listed in the EC Declaration of
Conformity.
It is recommended to be informed about the use of safety symbols in
this manual by reading the opposite page Important user information.
The relevant safety information for this manual will be found listed
early in each manual chapter.

ML180-MLT350 Dehumidifiers
61 Introduction 190TGB-1034-A
1.4 Markings
Figure 1-1. Location of labels
Figure 1-2. Example of identification plate content & Label details
1.5 Operator stations
The dehumidifier is controlled and supervised with the help of the
control panel, located on the front of the unit, see figure 3-1.
1.6 Fault indications
Faults are clearly indicated through an illuminated indicator on the
control panel, see figure 3-1.
Alarms related to air relative humidity are indicated in the display of
the RH98 (if fitted) operators panel, see section 7.4, RH98.
(GB)CHANGE FILTER
(GB)CHANGE FILTER
(GB)CHANGE FILTER
(GB)CHANGE FILTER
1
2
3
4
56
6
3
2
4
5
Type ML420
Fabr. No 0214 190XXX XXXXX
3 ~ 400V 50Hz
370W 42.kW
Max 4,57kW
Munters Europe AB
M
IP44
1
(GB) CHANGE FILTER
(SW) BYT FILTER
(FR) REMPLACER LE FILTER
(DE) FILTER AUSWECHSELN
6
1= Identification Plate 2= Dry Air Outlet
3= Wet Air Outlet 4= Process Air Inlet
5= React Air Inlet 6= ML180-MLT350 Filter

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 7
2 Installation
2.1 General
The ML Dehumidifiers intended for indoor installation.
The unit is inspected and checked prior to leaving the factory to
guarantee consistent quality and maximum reliability.
If the unit is to be put into storage, prior to installation, see section 2.5,
Storing the Equipment.
2.2 Safety
WARNING! The dehumidifier is heavy and can weigh in excess of 50kg. To
avoid accidents use only approved lifting equipment.
WARNING! All electrical equipment connections must be carried out in
accordance with local regulations and by qualified personnel.
WARNING! The unit must never be connected to a voltage or frequency other
than that for which is was designed and manufactured. Refer to the unit
identification plate if in doubt.
WARNING! Ensure that the mains power is isolated from the dehumidifier
prior to changing the orientation of the process and dry air connections.
CAUTION! The wet air ducting must always be insulated if there is a risk of
freezing. Due to the high moisture content in the wet air leaving the dehumidifier
condensation will readily form on the inside duct walls.
CAUTION! The dehumidifier has been designed to operate at specific process
airflows (corresponding to the fan sizes installed) and must not be directly
connected to air-conditioning systems.
CAUTION! Failure to correctly adjust the process and reactivation airflows
could cause the unit to malfunction.
CAUTION! When moving the dehumidifier always consider the possible risk of
the unit tipping over.

ML180-MLT350 Dehumidifiers
82 Installation 190TGB-1034-A
2.3 Moving the Equipment
WARNING! The dehumidifier is heavy and can weigh in excess of 50kg. To
avoid accidents use only approved lifting equipment.
The dehumidifier is delivered on a pallet and must be handled
carefully. All panel doors of the unit must be closed during transport.
Provided that the dehumidifier is still secured to its delivery pallet, it
can be moved using a fork-lift truck.
CAUTION! When moving the dehumidifier always consider the possible risk of
the unit tipping over.
Figure 2-1. Example of moving the dehumidifier
Weight of the dehumidifier can be found in section 6.3, Dimensions and
service space.
2.4 Packaging and Delivery Inspection.
1. Check the delivery against the packing list, consignment note or
other delivery documentation and check that everything is included
and nothing is damaged.
2. Contact Munters immediately if delivery is not complete in order to
avoid installation delays.
3. If the unit is to be put into storage, prior to installation, see section
2.5, Storing the Equipment.
NOTE! If the installation is not to be carried out immediately after the arrival of the
equipment it is advisable to leave the packing material in place on the
dehumidifier, or to re-use the packaging material to provide temporary protection
for the unit during later transport to the installation location and during
installation.
4. Remove all packing material from the unit, check carefully to make
sure that no damage has occurred during transport.
5. Any visible damage must be reported in writing to Munters prior to
the start of installation.
2.5 Storing the Equipment
The following is important if the dehumidifier is to be stored prior to
installation:
• Place the dehumidifier on a horizontal surface.
• Protect the dehumidifier from physical damage.
• Store the dehumidifier under cover and protect it from dust, frost,
rain and aggressive contaminants.

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 9
2.6 Location Requirements
The dehumidifier is intended for indoor installation.
It is important that the intended installation site meets the location and
space requirements for the equipment in order to achieve the best
possible performance and trouble-free operation.
The unit should be placed in an upright level position inside or outside
the space to be dehumidified.
For unit and service dimensions, see section 6.3, Dimensions and service
space.
NOTE! It is important, both for maintenance and for service, that the minimum service
space for service access are compiled with.
2.7 Process and Dry Air Connections
The front and back panels are interchangeable, so that the connections
for process and dry air may be situated either on the left or right side of
the unit.
ML-Series dehumidifiers are delivered with the process and dry air
connections on the left side of the unit. If it is required to the change
the orientation, so that the connections are on the right side of the
unit, proceed as follows:
WARNING! Ensure that mains power is isolated from the dehumidifier prior to
changing the orientation of the process and dry air connections.
1. Remove the two bolts (B) securing the front panel and carefully
remove the panel.
2. Remove the two bolts securing the rear panel and carefully remove
the panel.
3. Remove the two bolts (A) and washers, securing the control and top
panels to the unit and carefully remove the top panel.
4. Remove the cable duct covers (C), re-route the cables and fit the
control panel (D) to the opposite side of the unit. Refit the cable
duct covers.
5. Refit the front, rear and top panels in the new position.
Figure 2-2. Changing panel orientation
B
A
C
D

ML180-MLT350 Dehumidifiers
10 2 Installation 190TGB-1034-A
2.8 Ducting
2.8.1 General recommendations
The connections for process and reactivation air are designed in
accordance with the recommendations in ISO 7807. The rectangular
duct connections contain tapped inserts for M8 bolt fixings.
CAUTION! The dehumidifier has been designed to operate at specific process
airflows (corresponding to the fan sizes installed) and must not be directly
connected to air-conditioning systems.
• When installing ductwork between the dehumidifier and the inlet
and outlet connections, the following recommendations should be
observed:
• The length of ductwork should be kept as short as possible to
minimise static air pressure losses.
• To maintain performance, all rigid process or reactivation air
ductwork joints must be air and vapour tight.
• The process air ductwork should be insulated to prevent
condensation from developing on the outside of the duct whenever
the temperature of the air within the duct falls below the dewpoint
of the ambient air through which the ductwork is routed.
• The ducting must always be insulated when there is a risk of
freezing.
• The wet air leaving the dehumidifier will, due to high moisture
content, condense on the inside duct walls. This must be avoided by
insulating the ducts.
• Horizontal duct-runs should be installed sloping downwards (away
from the dehumidifier) to allow for condensate drainage. On the
wet air outlet ducting, suitable condensate drains should be installed
at low points in the ductwork. Refer to figure 2-3, Wet air outlet design.
• Ensure that access for operation and servicing is not restricted when
designing and installing ducting. For details refer to section 6.3,
Dimensions and service space.
• To reduce noise and/or vibration being transmitted along rigid
ductwork, good quality, airtight flexible connections can be fitted.
• Ducts mounted directly onto the dehumidifier should be adequately
supported to minimise the load and stress due to the duct weight
and movement.
• Dampers for balancing the airflows must be installed in the dry air
outlet and reactivation air inlet ducts. The correct airflows are
essential for maintaining the operating efficiency of the unit. For
airflow adjustment details, see section 2.15, Airflow Check and
Adjustment.

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 11
• The total resistance in the process and reactivation air ductwork
must not exceed the performance rating of the fans fitted in the
dehumidifier. For details of minimum available static pressure, see
section 6.5, Technical Specifications.
Figure 2-3. Wet air outlet design
2.8.2 Ductwork for Outdoor Air Inlet
When bringing outside ambient air into the dehumidifier, the opening
to the inlet duct should be sufficiently located above ground level to
prevent the pick-up of dust and debris. The ducting should be designed
to prevent rain and snow from being drawn into the dehumidifier. The
air inlet must be located away from possible contaminations such as
engine exhaust gases, steam and harmful vapours.
To prevent the wet (outlet) air humidifying the reactivation (inlet) air,
the air inlet for reactivation must be located at least 2m from the air
outlet for wet air Refer to figure 2-4, Outdoor air inlet design.
2.8.3 Ductwork for Wet Air Outlet
Wet air ducting should be manufactured in corrosion resistant material
(e.g. stainless steel, aluminium or plastic) and should be capable of
withstanding temperatures of up to 100°C.
CAUTION! The wet air ducting must always be insulated if there is a risk of
freezing. Due to the high moisture content in the wet air leaving the dehumidifier
condensation will readily form on the inside duct walls.
Horizontal duct-runs must therefore be installed sloping downwards (away from
the dehumidifier) to allow for condensate drainage. The slope should be a
minimum of 2cm per meter duct. In addition, 5mm drain hole should be drilled
at the low points in the duct to prevent water accumulating in the duct. See
figure 2-3, Wet air outlet design.
Wire netting, mesh
width about 10 mm
Wire netting, mesh
width about 10 mm To Condensate Drain
Wet
Air
Wet
Air
Downward slope away
from dehumidifier
Horizontal Wet
Air Outlet Vertical Wet
Air Outlet

ML180-MLT350 Dehumidifiers
12 2 Installation 190TGB-1034-A
Figure 2-4. Outdoor air inlet design
Figure 2-5. Required ductwork
2.9 Precaution for unit using LI desiccant rotor
To prevent the lithium chloride (LI) desiccant rotor becoming
overloaded when the dehumidifier has been switched off, air with a
relative humidity exceeding 80% must not pass through the rotor!
It is recommended to install motorized and air tight shut-off dampers
in the inlet process and reactivation air openings to the dehumidifier.
This is to prevent air with a very high relative humidity from
inadvertently being drawn through the rotor by a chimney effect
created by ancillary equipment.
This is particularly important when the process air is drawn from
outdoors, or the system has been fitted with a pre-cooler. Failure to
observe these precautions could result in a serious loss of performance
and may cause permanent damage to the rotor.
Rectangular Duct Round Duct
Wire netting, mesh
width about 10mm Wire netting, mesh
width about 10mm
ML
Munters
420
1
3
5
5
4
C
B
D
A
2
A = Process air inlet
B = Dry air outlet
C = Reactivation air inlet
D = Wet air outlet
1 = Dry air damper
2 = External filter box (option)
3 = Duct transition
4 = Reactivation air damper
5 = Outlet duct (wire netting)

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 13
2.10 Installation Examples
2.10.1 Closed System
Figure 2-6. Closed Airflow System
2.10.2 Open System
Figure 2-7. Open Airflow System
ML
Munters
420
ML
Munters
420
The closed airflow system is mainly used where the room to
be dehumidified contains little or no ventilation, and is
partially sealed.
A closed airflow system offers the advantage of simple
design and therefore low installation costs. Usually a closed
system will minimise the size of the dehumidifier required,
and because the environment is partially sealed, the
operating costs for the dehumidifier will also be minimised.
ML
Munters
420
ML
Munters
420
Open airflow systems can be utilized in place of closed
systems to overcome the following problem areas:
High level of dust or corrosive particles in the room.
Harmful gasses or vapours which must not be
recirculated.
Problems arranging air recirculation where several
rooms are served by the same dehumidifier. Specially
where recirculated air must not be mixed.
A pressured environment is desired to prevent
uncontrolled infiltration of humid air, particularly where
low relative humidity is required.
When an open airflow system is installed, all leaks in the
airflow much be controlled within an acceptable tolerance.

ML180-MLT350 Dehumidifiers
14 2 Installation 190TGB-1034-A
2.11 Electrical Connections
2.11.1 Mains Supply
WARNING! All electrical equipment connections must be carried out in
accordance with local regulations and by qualified personnel.
WARNING! The unit must never be connected to a voltage or frequency other
than that for which it was designed and manufactured. Refer to the unit
identification plate if in doubt.
ML180 & MLT350 dehumidifiers are supplied complete with a pre-
wired mains cable. The cable is fitted with a multi-pin plug suitable for
connection to a single phase earthed mains socket.
The ML270 is designed for 3-phase AC operation. Each unit is supplied
complete with all the internal wiring installed and configured in
accordance with the specified voltage and frequency on the
identification plate.
ML270 (only): We strongly recommend that an external isolator be
installed and placed close to the ML270 unit. The isolator can be used
to switch of the power to the unit in case of an emergency.
NOTE! Supply voltage must not vary more than 10% of the specified operating voltage.
The unit must be adequately connected to earth.
ML270 (only): The power supply cables must be of the correct size for
the dehumidifier being installed.
For connection details refer to the identification plate and Electrical
Circuit Supplement or refer to section 6.5, Technical Specifications.
2.12 External Humidistat
ML-Series dehumidifiers are pre-wired so that when the unit is in the
AUTomatic mode it can be controlled by an externally mounted
humidistat.
ML180-MLT350 have been designed with a one-step heater, and
therefore control is limited to switching the unit on and off using a one-
step humidistat.
A low voltage connector (mounted on the side of the unit) is provided
for electrical connection of a single-stage humidistat. For details refer
to the units Circuit Diagram Supplement.
2.12.1 Location Requirements
The humidistat should be mounted 1-1.5m above the floor and
positioned so that it is not exposed directly to dry air from the unit or
incoming moist air from opening and closing doors. It may not be
placed close to a heat source or so that it is exposed to direct sunlight.
2.12.2 Electrical Specifications
The humidistat connecting cable should have a conductor cross-
sectional area of not less than 0,75 mm2and must have an insulation
resistance rating in excess of 500 VAC.

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 15
The humidistat must be electrically compatible with the
dehumidifier’s extra low voltage control circuit.
The humidistat must be designed so that the contacts close on a
rising RH to complete the control circuit and start the dehumidifier.
Voltage drops may be experienced when using excessively long
cables.
At operation, the voltage must be 24VAC measured at the dedicated
terminals, used for connecting the humidistat to the dehumidifier. If
the measured voltage is less than 20VAC, a separate relay controlled by
the humdistat must be used.
2.13 Pre-Start settings
ML180-MLT350 units are equipped with a number of standard features
requiring a few selections and settings before the unit is put in
operation for the first time.
Some features require connection of external equipment. For wiring
details refer to the Circuit Diagram Supplement supplied with this unit.
2.13.1 One-step humidistat
NOTE! Where no humidistat is connected to the unit, the dehumidifier will be operating
at maximum output for as long as the unit is switched on.
Where a one-step humidistat is fitted, the dehumidifier will switch on
and off under the control of the humidistat. The one-step humidistat is
connected in accordance with the Circuit Diagram Supplement.
2.14 Pre-Start Checks
Before starting the dehumidifier for the first time, ensure that the
mains power supply is isolated from the dehumidifier and carry-out the
following checks:
1. Check that the Mode switch on the dehumidifier is in the “OFF”
position, see figure 3-1, Control Panel.
2. Check the air intake filters for damage and proper fixation and also
check that all areas inside the unit are clean.
3. Visually inspect all ducting and duct connections to make sure that
all connections have been correctly installed and that there are no
signs of damage to the system. Also check that all ducts are free from
obstacles blocking the air passage.
4. Remove the top panel and check that none of the main contact
breakers in the electrical control panel have been tripped. For
details refer to the wiring diagrams provided with the unit.
5. Check that the incoming power supply voltage is correct and that
the cables are correctly connected.
6. If a humidistat has been installed, check that it has been correctly
positioned in the room and has been correctly connected to the
unit, see section 2.12, External Humidistat.

ML180-MLT350 Dehumidifiers
16 2 Installation 190TGB-1034-A
7. The ML270 has a 3 phase fan motor and the rotation direction of
the fan impeller must be checked after connection to the power
supply. Open the front panel of the dehumidifier and take out the
process filter. Start the dehumidifier and check that the fan impeller
is rotating. Stop the dehumidifier and observe the impeller just
before it stops rotating to check that the rotation direction is
clockwise.
8. If a RH98 has been installed, check that the sensor has been
correctly positioned in the room and has been correctly connected
to the unit, see appendix 7.4, RH98.
9. Set the process and reactivation airflow dampers to the fully open
position.
2.15 Airflow Check and Adjustment
2.15.1 General
To obtain the design performance, the dry air and reactivation airflow
dampers must be correctly adjusted in accordance with the rated
airflow, see section 6.5, Technical Specifications.
If required contact Munters Product Service to receive help with
commissioning the dehumidifier installation, see addresses on the back
cover of this manual for your local Munters representative.
CAUTION! Failure to correctly adjust the process and reactivation airflows
could cause the unit to malfunction.
1. Using the dampers installed in the dry air outlet and reactivation air
inlet ducts, adjust the process and reactivation airflows to the correct
rated airflow.
2. Start the dehumidifier and let it run on full power for approximately
5 minutes to allow the reactivation heater to reach its normal
operating temperature. Refer to Chapter 3, Operation.
3. Check that the temperature differential between the reactivation
supply air and the reactivation air (indicated on the temperature
display) is 95°C (tolerance ±5°C).

ML180-MLT350 Dehumidifiers
190TGB-1034-A 2 Installation 17
4. If the temperature differential is out of tolerance limit by 5%, adjust
the reactivation air damper in small stages allowing the temperature
display to stabilise after each adjustment) until reactivation
temperature reading is within the specified tolerances.
.
Figure 2-8. Airflow Chart
140
-20
120
100
-40
60
80
6
0
40
200 t
i
˚C
t
u
˚C
Symbols:
ti= Inlet air temperature (°C)
tu= Reactivation air temperature (°C)
Example:
Inlet air temperature (ti) = 15°C
Reactivation air temperature = 110°C
Temperature increase = 95°C

ML180-MLT350 Dehumidifiers
18 3Operation 190TGB-1034-A
3 Operation
3.1 General
The ML180-MLT350 dehumidifiers are equipped with a control panel
that contains mode switches and LED indicators.
The mode switch of the control panel has two operating modes:
MAN (Manual mode)
The dehumidifiers fan, rotor and reactivation heater operate
continuously with full capacity.
AUT (Automatic mode)
The dehumidifiers fan, rotor and reactivation heater operate when the
Relative Humidity rises above the desired value.
3.2 Safety
CAUTION! To prevent damage to the fans, the unit must not be run for longer
than a few minutes prior to setting-up the process and reactivation airflows.
CAUTION! Failure to correctly adjust the process and reactivations airflows
could cause the unit to malfunction.
3.3 Emergency stop
ML180 & MLT350
To start and stop the unit in normal operation the Run/Stop switch is
used. In case of an emergency unplug the unit from the wall outlet.
ML270
To start and stop the unit in normal operation the Run/Stop switch is
used. In case of an emergency switch the unit off using the external
isolator (if fitted).
3.4 Pre-Start Checks
Before starting the dehumidifier for the first time, carry out checks
according to section 2.14, Pre-Start Checks and section 2.15, Airflow Check
and Adjustment.
3.5 Operating the unit
3.5.1 Manual Mode
1. Ensure the Run/Stop switch is set to the position.
2. Operate the mode switch to the MAN position.
3. Connect mains power to the unit and ensure that the power
connected indicator is illuminated.
4. Operate the run/stop switch to the position. Ensure that the
unit running indicator is lit and the unit is operating.

ML180-MLT350 Dehumidifiers
190TGB-1034-A 3 Operation 19
5. Operate the run/stop switch to the position and check that
the unit stops and that the unit running indicator goes out.
For details on the Control panel, see figure 3-1, Control Panel.
3.5.2 Automatic Mode - Humidistat
For the unit to operate in the AUTOmatic mode a one-step humidistat
must be installed and correctly connected to the unit. For details see
section 2.12, External Humidistat.
1. Set the mode switch to the AUTO position.
2. Adjust the humidistat set point for the minimum relative humidity
(RH) value. Operate the run/stop switch to the position.
Ensure that the unit running indicator is lit and the unit is
operating.
3. Slowly increase the humidistat set-point and check that the unit
switches off when the set-point matches the RH in the room where
the humidistat is installed. Check that the unit running indicator
remains on.
4. Slowly decrease the humidistat set-point and check that the unit
switches on when the set-point falls below the RH in the room where
the humidistat is installed.
5. Operate the run/stop switch to the position and check that the
unit stops and that the unit running indicator goes out.
6. Reset the humidistat to the desired set-point.
For details on the Control panel, see figure 3-1, Control Panel.
3.5.3 Automatic Mode - RH98
If the unit has been supplied with a factory fitted RH98 control system
(option) the external transmitter must be installed and correctly
connected to the unit. The same location requirements are valid for
the humidistat and the RH98, see section 2.12, External Humidistat. For
details on operation see section 7.4, RH98.
1. Set the mode switch to the AUTO position.
2. Adjust the RH98 set point for the minimum relative humidity (RH)
value. Operate the run/stop switch to the position. Ensure
that the unit running indicator is lit and the unit is operating.
3. Slowly increase the RH98 set-point and check that the unit switches
off when the set-point matches the RH in the room where the
humidity transmitter is installed. Check that the unit running
indicator remains on.
4. Slowly decrease the RH98 set-point and check that the unit switches
on when the set-point falls below the RH in the room where the
humidity transmitter is installed.

ML180-MLT350 Dehumidifiers
20 3Operation 190TGB-1034-A
5. Operate the run/stop switch to the position and check that the
unit stops and that the unit running indicator goes out.
6. Reset the RH98 to the desired set-point.
For details on the Control panel, see figure 3-1, Control Panel.
3.6 Control Panel
Figure 3-1. Control Panel
Item Switch/Indicator Function
1 Run/Stop Switch With the run/stop switch selected to the position, the unit is switched off.
With the mode switch in the “MAN” position, operating the run/stop switch to the
position will start the dehumidifier.
With the mode switch in the “AUTO” position, operating the run/stop switch to the
position will allow an external humidistat or RH98 to control the operation of
the dehumidifier.
2 Mode Switch With the mode switch in “MAN” position, the dehumidifier will operate in the manual
mode. In this mode the unit will run continuously when the run/stop switch is
operated to the position.
With the switch in the “AUTO” position, the dehumidifier will operate in the automatic
mode. In this mode a humidistat or RH98 must be connected to the unit. When the
run/stop switch is operated to the position, the humidistat or RH98
determines when the dehumidifier will start and stop.
3 Power Connected Indicator Indicates that mains power is connected to the dehumidifier.
4 Unit Running Indicator Indicates that the dehumidifier is running, or is ready to start on a signal from the
humidistat or RH98 (automatic mode).
5 Fault Warning Indicator Indicates that the unit has shut-down due to the control circuit detecting that either
the high temperature cut-out or the fan motor overload has tripped.
For units fitted with an air cooled condenser, the fault warning indicator is activated
when there is a condenser fan or heater fault.
6 Temperature Gauge Indicates the Reactivation Air temperature.
7 Running time meter 1Indicates the number of hours that the dehumidifier has been operating.
1Optional component
Table 3-1. Function of the Control Panel
16
5
4
32