Munters Dehumidifier ML420-1350, MLT800-1400 User Manual

1. Important user information

1.1. Intended use

Munters dehumidifiers are intended for the dehumidification of air. Any other use, or use contrary to the instructions in this manual, can cause personal injury and damage to the unit and other property.

Modifications to the unit are not allowed without prior approval by Munters. Installation of additional devices is only allowed after written agreement by Munters.

1.2. Warranty

The warranty is based on the terms of sale and delivery of Munters. The warranty is not valid if repairs or modifications are carried out without written agreement from Munters, or if the unit does not operate under the agreed conditions.

The warranty is limited to a free exchange of parts or components that have failed due to defects in materials or workmanship.

All warranty claims must include proof that the fault occurred within the warranty period and that the unit was used according to specifications. Claims must specify the unit type and serial number, found on the identification label.

Commissioning/Start-up inspection "S" by Munters is mandatory to validate the full warranty.

It is a condition of the warranty that the unit is serviced and maintained by a qualified Munters engineer or Munters approved engineer for the full warranty period. Service and maintenance must be documented for the warranty to be valid.

1.3. Safety information

Information about dangers is indicated by the common hazard symbol:

! WARNING: Indicates a possible danger that can lead to personal injury.

! CAUTION: Indicates a possible danger that can lead to damage to the unit or other property, or cause environmental damage.

? NOTE: Highlights supplementary information for optimal use of the unit.

1.4. Copyright

The contents of this manual can be changed without prior notice.

? NOTE: This manual contains information protected by copyright laws. Reproduction or transmission of any part of this manual without written consent from Munters is not allowed.

Munters Europe AB, P.O. Box 1150, SE-16426 KISTA Sweden

2. Introduction

2.1. About this manual

This manual provides necessary information for users to install and use the dehumidifier safely and efficiently.

Read through the manual before installing and using the dehumidifier.

Contact your nearest Munters office for any questions regarding installation or use.

Store this manual in a permanent location near the dehumidifier.

2.2. Unintended use

The following restrictions on use apply:

• The dehumidifier is not intended for outdoor installation.
• The dehumidifier is not intended for use in classified areas requiring explosion safety compliant equipment.
• The dehumidifier must not be installed near heat-generating devices that could damage the equipment.

2.3. Safety

The information in this manual does not supersede individual responsibilities or local regulations.

During operation and work with the machine, the individual is always responsible for considering:

• The safety of all persons concerned.
• The safety of the unit and other property.
• The protection of the environment.

! WARNING:

• All electrical installations must be performed by an authorized electrician in accordance with local regulations. Incorrect installation can cause electrical shock hazards and damage to the unit.
• Commissioning and initial start-up must be done by authorized personnel only.
• The unit must never be connected to a voltage or frequency other than that specified on the identification plate. Excessive line voltage can cause electrical shock hazards and damage to the unit.
• Rotating fan blades can cause serious injury. Operate the unit only with connected air ducts.
• The unit can restart automatically after a power cut. Ensure the main power switch is set and locked in the OFF position before any service or maintenance work.
• Use only approved lifting equipment to prevent personal injury and damage to the unit.
• Move the unit carefully to prevent overturning.
• If the rotor is to be cut into pieces, wear a suitable CE-marked face mask selected and fitted according to applicable safety standards to protect from dust.

2.4. Marking

Diagram showing the unit with numbered parts:

• 1. Unit identification plate
• 2. Dry air outlet
• 3. Wet air outlet
• 4. Process air inlet
• 5. Reactivation air inlet

Example identification plate: The first four digits of the fabrication number indicate the year and week (YYWW) of production.

Munters Identification Plate:

Fabr. No. 1835 XXXXXX XXXXXX

Fabr. year 2018

CE

Made in Sweden

Munters Europe AB

P.O. Box 1150

164 26 Kista, Sweden

Labels:

[Label 2], [Label 3], [Label 4], [Label 5]

3. Dehumidifier design

3.1. Product description

The ML series desiccant dehumidifiers are designed for effective dehumidification in environments requiring low air humidity.

The dehumidifier features an encapsulated rotor unit with a durable thermoset plastic casing containing isolated sections for balanced dehumidification, reactivation, and heat recovery airflows.

The dehumidifier is manufactured according to uniform European standards and CE-marking requirements.

3.2. Function overview

Diagram illustrating internal airflows:

• 1. Process air
• 2. Dry air
• 3. Reactivation air
• 4. Wet air

The desiccant rotor, composed of numerous small air channels, is the adsorption dehumidifying component. It's made of a composite material effective in attracting and retaining water vapor and is divided into two zones.

Process air passes through the largest zone of the rotor and exits as dry air. The slow rotation ensures that incoming air always meets a dry zone, enabling continuous dehumidification.

Reactivation air is heated and passes through the rotor in the opposite direction to the process air, exiting as wet (warm, moist) air. This process allows the dehumidifier to function effectively even at freezing temperatures.

3.3. Main components

Diagram showing main components:

• 1. Electrical panel
• 2. Process fan
• 3. Reactivation fan
• 4. Reactivation air filter
• 5. Process air filter
• 6. Reactivation heater
• 7. Drive motor
• 8. Rotor
• 9. Upper rotor cover

? NOTE: The ML420 unit has a single fan motor located between the process and reactivation impellers.

3.4. Insulated process air inlet

For dehumidifying cold process air, often with a pre-cooler, condensate can form on the inlet side. ML-series dehumidifiers can be supplied in an IPI version where the process air fan is enclosed in an insulated box to prevent condensation.

4. Transport, delivery inspection and storage

4.1. Transport

The dehumidifier is delivered on a pallet and requires careful handling. All panel doors must be closed during transport. If secured to the pallet, it can be moved with a forklift truck.

! WARNING: Move the unit carefully to prevent overturning.

The weight of the dehumidifier can be found in the Technical data section.

4.2. Delivery inspection

• Inspect the delivery against the delivery note, order confirmation, or other documentation. Ensure all items are included and undamaged.
• Contact Munters immediately if the delivery is incomplete or damaged to avoid installation delays.
• Document any damage to the packaging with photos before removing it.
• Remove all packaging material and check for any damage incurred during transport.
• Document any damage to the unit with photos.
• Report any visible damage in writing to Munters within 3 days and prior to installation.
• Dispose of packaging material according to local regulations.

4.3. Storage

Follow these instructions for storing the dehumidifier before installation:

• Place the dehumidifier upright on a horizontal surface.
• Reuse packaging material for protection.
• Protect the dehumidifier from physical damage.
• Store the dehumidifier under cover, protected from dust, rain, and aggressive contaminants.

5. Installation

5.1. Safety

! WARNING:

• All electrical installations must be performed by an authorized electrician in accordance with local regulations. Incorrect installation can cause electrical shock hazards and damage to the unit.
• The unit must never be connected to a voltage or frequency other than that specified on the identification plate. Excessive line voltage can cause electrical shock hazards and damage to the unit.
• Move the unit carefully to prevent overturning.
• Use only approved lifting equipment to prevent personal injury and damage to the unit.
• Rotating fan blades can cause serious injury. Operate the unit only with connected air ducts.

! CAUTION: Do not sit, stand, or place objects on the unit.

5.2. Installation site requirements

? NOTE: It is important that the installation site meets the location and space requirements for optimal performance and trouble-free operation.

Adhere to minimum service space requirements for maintenance purposes.

The dehumidifier is intended for indoor installation only.

For space requirements, refer to the Dimensions and service space section.

? NOTE: If vibration reduction is needed, contact Munters for instructions.

5.3. Foundation

The dehumidifier must be installed on a level floor or platform with a floor loading capacity sufficient for the unit's total weight. Special foundations are not required if the maximum floor loading weight is not exceeded.

If local regulations require floor attachment, use the mounting holes in the base frame for foundation screws.

Diagram showing dimensions and mounting hole pattern:

Dimensions: 81 mm, 51 mm, 613 mm, 427 mm.

Mounting holes: Ø7 (4x).

5.4. Duct installation

5.4.1. General recommendations

Process and reactivation air connections comply with ISO 13351 recommendations. Rectangular duct connections have tapped inserts for M8 screws.

! WARNING: The dehumidifier is designed to operate at specific process airflows corresponding to the installed fan sizes.

? NOTE: The IPI version lacks a process air filter. The process air inlet must be connected to cold/pre-cooled and filtered air via a duct.

• Keep ductwork length as short as possible to minimize static air pressure losses.
• Ensure all rigid process or reactivation air ductwork joints are air and vapor tight for performance.
• Insulate process air ductwork to prevent condensation on the outside when the internal air temperature falls below the ambient dewpoint.
• Ducts must be insulated if there is a risk of freezing.
• Insulate wet air ducts to reduce condensation on the inside walls due to high moisture content.
• Horizontal wet air ducts must slope downwards (away from the dehumidifier) for condensation drainage. Install suitable condensation drains at low points.
• Ensure ducting design and installation allow access for operation and servicing.
• Use airtight flexible connections to reduce noise and vibration transmission along rigid ducts.
• Ducts mounted directly on the unit must be independently supported to minimize load.
• Install dampers in the dry air outlet and reactivation air inlet ducts for airflow adjustment. Correct airflows are essential for unit efficiency.
• The total pressure drop in the process and reactivation ductwork must not exceed the available fan pressure.

Diagram of duct connections:

Ducts required for installation:

• 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/inlet duct (wire netting)

5.4.2. Duct for outdoor air inlet

Locate the outdoor air inlet duct opening sufficiently high above ground to prevent dust and debris intake. Design ducting to prevent rain and snow entry. Position the air inlet away from contaminants like engine exhaust gases, steam, and harmful vapors.

The air inlet for reactivation must be at least 2 m from the wet air outlet to prevent humidifying reactivation air.

Attach a wire net with approximately 10 mm mesh width to the outer end of the duct to prevent animal entry.

Diagrams showing ducting types: Rectangular ducting, Round ducting, Wire netting.

5.4.3. Duct for wet air outlet

The wet air duct material must withstand corrosion and temperatures up to 100 °C. Insulate the duct if there is a risk of condensation, as the high moisture content can cause condensation on the inside walls.

Horizontal ducts must slope downwards (away from the dehumidifier) for condensation drainage. The duct slope should be at least 2 cm/m. Install drainage holes (5 mm) at low points to prevent water accumulation.

Attach a wire net with approximately 10 mm mesh width to the outer end of the duct to prevent animal entry.

Diagram showing wet air outlet ducting: Horizontal wet air outlet, Vertical wet air outlet, Wire netting, Downward slope, Condensate drainage.

5.5. Precautionary measures for units with lithium chloride rotor

The standard delivery includes a Munters high-performance desiccant rotor HPS (High Performance Silica gel). If the dehumidifier is delivered with an LI rotor (lithium chloride), ensure the rotor does not become loaded with moisture when the dehumidifier is off.

! CAUTION: Ensure that no air passing through the rotor has a relative humidity greater than 80%.

It is recommended to install closing dampers in the process and reactivation air inlets to prevent air with high relative humidity from being drawn through the rotor and into the room. This is particularly important when process air is drawn from outdoors or when the system includes a pre-cooler.

5.6. Electrical installation

! WARNING:

• All electrical installations must be performed by an authorized electrician in accordance with local regulations. Incorrect installation can cause electrical shock hazards and damage to the unit.
• The unit must never be connected to a voltage or frequency other than that specified on the identification plate. Excessive line voltage can cause electrical shock hazards and damage to the unit.

! CAUTION: The supply voltage must not differ from the specified operating voltage by more than ±10%.

The dehumidifier is delivered with internal wiring installed and configured for the specified voltage and frequency on the identification plate.

The mains power supply connects directly to the main power switch in the unit. The supply cable and main fuses must be rated for the unit.

? NOTE: If the unit is connected to power via an RCD (Residual Current Device), it must be of "industrial" type B with a sensitivity of 100 mA or greater to avoid tripping.

Maximum permissible system impedance is 0.01 Ohm.

For connection details, refer to the identification plate and wiring diagram.

5.7. External humidity sensor

The dehumidifier is normally delivered with a humidity sensor. Sensors have an output signal of 4...20 mA for temperature and humidity, respectively.

Depending on the control system, the following options are available:

• Relative humidity sensor (wall-mounted): Measurement range: 0-100% RH, -5 to +55 °C temperature.
• Relative humidity sensor (duct-mounted): Measurement range: 0-100% RH, -20 to +80 °C temperature.
• Dewpoint sensor: Measurement range: -80 to +20 °C dewpoint temperature.
• Absolute humidity sensor (duct-mounted): Measurement range: 0-20 g/kg.

The humidity sensor regulates the dehumidifier in AUTO mode and indicates current humidity.

For correct operation, the humidity sensor must be connected with a shielded 5G, 0.75 mm² electric cable.

When wall-mounted, the sensor should be 1-1.5 m above the floor, positioned away from direct airflows from the unit, humid air from open doors, heat sources, or direct sunlight.

A duct-mounted sensor must be installed far enough from the unit outlet for a stable humidity reading.

Refer to the assembly instructions provided with the humidity sensor for more information.

6. Commissioning

! WARNING: Commissioning and initial start-up must be done by authorized personnel only.

! WARNING: Rotating fan blades can cause serious injury. Operate the unit only with connected air ducts.

! CAUTION: Airflows must never exceed rated airflows without consulting Munters for verification.

! CAUTION: Incorrect airflow adjustment can cause unit malfunction and may invalidate the warranty.

6.1. Inspection before first start

1. Ensure the main power switch is set to position O.
2. Open the electrical panel cover and verify that no circuit breakers or automatic fuses have tripped.
3. Examine air intake filters for damage and correct installation. Ensure all unit sections are clean.
4. Inspect all ducts and duct connections for correct installation and damage. Ensure ducts are free from obstructions.
5. Verify the incoming power supply voltage and correct cable connections.
6. Ensure the humidity sensor is correctly positioned and connected to the electrical panel.

6.2. Function test

1. Set the main power switch to position 1.
2. Start the unit.
3. Verify the rotor rotation direction matches the arrows. If incorrect, interchange incoming wires in the main power switch.

6.3. Airflow adjustment

Correct process and reactivation airflow adjustment is crucial for optimal performance.

Contact Munters for assistance with installation and settings.

1. Adjust dampers in the dry air outlet and reactivation air inlet ducts to the correct rated airflows.
2. Start the dehumidifier at full power for 8 minutes to allow the reactivation heater to reach its normal operating temperature.
3. Check the temperature difference between reactivation inlet air and reactivation temperature. It should be 95 °C (tolerance ±5 °C). If outside the tolerance, adjust the reactivation air damper in small steps until the temperature is within limits. Allow temperature to stabilize after each adjustment.

EXAMPLE: Inlet air temperature 15 °C and reactivation air temperature 110 °C results in a temperature increase of 95 °C.

7. Operation

7.1. Main power switch

Image of the main power switch (SIEMENS).

Main power switch:

• Position O: Unit is not powered.
• Position 1: Unit is powered and can be started.

7.2. Control system

For detailed information on the control system, parameters, and settings, refer to the control system supplement.

7.3. Start and stop

Start and stop operations are controlled via the control system panel (AirC) or the mode selector (Climatix).

! CAUTION: To dissipate residual heat, fans and the drive motor continue running after the unit is switched off until the temperature drops below 50 °C. Do not turn off the main power before the fans have completely stopped.

7.3.1. Start/stop from control system panel

Image of the control system panel display.

Press the start/stop button in the upper right corner to operate the unit.

• From Off: Press once for Automatic mode (sensor control).
• From Off or Automatic: Press and hold for >3 seconds for Manual mode (100% capacity dehumidification).
• From Automatic or Manual: Press once for Off.

7.3.2. Start/stop with mode selector

(Only with Climatix control system)

Image of the mode selector dial (AUTO, MAN, 0).

• AUTO: Dehumidifier controlled by internal humidity setpoint or external input signal.
• MAN: Fans, rotor, and reactivation heater run continuously at full capacity.

8. Service and maintenance

8.1. Safety

! WARNING: The unit can restart automatically after a power cut. Ensure the main power switch is set and locked in the OFF position before any service or maintenance work.

! WARNING: Rotating fan blades can cause serious injury. Operate the unit only with connected air ducts.

8.2. General

Service and maintenance intervals depend on operating conditions and the environment. More frequent maintenance may be needed in dusty environments or during intensive use.

The control system includes a service indicator that triggers a service alarm based on operating hours or a preset date.

Munters offers comprehensive services, including commissioning, start-up, and advanced maintenance packages. Contact your local Munters representative for details.

8.3. Extended warranty

Munters offers an extended warranty under standard terms when a service agreement is signed. Details are available upon request.

8.4. Service alternatives

In addition to commissioning (S), four standard service alternatives (A-D) are available:

• A: Inspection and filter replacement if necessary. General function inspection.
• B: Includes A, plus safety inspection and capacity, temperature, and humidity regulation measurements.
• C: Includes B, plus preventive replacement of some components after 3 years.
• D: Includes C, plus preventive replacement of some components after 6 years.

? NOTE: Contact Munters for service or repair. Insufficient or incorrect maintenance can lead to operating faults.

8.5. Maintenance schedule

Table detailing maintenance tasks based on service alternative and operating time/calendar time.

? NOTE: Service should be performed at indicated operating hours (4'=4000 hours) or calendar time, whichever comes first. The schedule restarts after service alternative D.

8.6. Preventive replacements

The following components should be replaced preventively at indicated intervals:

8.7. Filter change

Replace filters every 6 months if necessary. Follow the steps below:

1. Remove the lower front panel using Allen Key No. 5.
2. Pull out the filter cartridge.
3. Clean the filter housing.
4. Insert a new filter, ensuring correct airflow direction (follow the arrow).
5. Lift the panel into place, ensuring the two bottom hooks fit correctly.
6. Tighten the two top screws.

Images illustrating the filter change process.

8.8. Cleaning

Use a pH-neutral soapy water solution and a soft sponge for cleaning the unit casing.

When cleaning the inside, avoid contact with the rotor and wipe surfaces dry.

Use a vacuum cleaner with a brush head for the rotor. Contact Munters for instructions if vacuum cleaning is insufficient.

9. Technical specification

9.1. Dimensions and service space

Diagrams showing unit dimensions and required service space for duct connections.

Minimum required service space: X=700 mm, Y=500 mm, Z=100 mm.

Table of dimensions (mm) for ML/MLT models:

9.2. Capacity diagrams

Approximate capacity in kg/h. Contact Munters for more detailed information.

? NOTE: The figures are based on rated airflow.

Key for diagrams:

1. Process air temperature (°C)
2. Process air relative humidity (% RH)
3. Dehumidification capacity (moisture removal per hour) (kg/h)

Capacity diagrams for ML420, MLT800, ML690, ML1100, ML1350, MLT1400.

9.3. Technical data

Table of technical data for Process air, Reactivation air, Rated current, Reactivation heater, and Miscellaneous data.

Table of technical data continued:

¹ Figures quoted are based on fan inlet temperature of 20°C, and an air density of 1.2 kg/m³.

² Without optional F5 or F7 filter boxes.

³ ML420 dehumidifiers have a single motor driving both process air and reactivation air fans.

⁴ Contacts used to give an external indication (output).

9.4. Sound data

9.4.1. Definition

Diagram showing duct connections:

• 1. Ductwork for dry air
• 2. Ductwork for process air
• 3. Ductwork for reactivation air
• 4. Ductwork for wet air

Values:

Lp(A) = Sound pressure (free field, Directivity factor Q=2, d=1 distance from source in meter)

Lp(A) = Lw(A) + 10Log(Q/(4πα²))

Lw(A) = Sound power level dB (A-weighted)

Sound data tables for ML420, ML690, MLT800, ML1100, ML1350, MLT1400, including sound to room and sound in ducts measurements.

10. Disposal

Dispose of the unit and consumables in accordance with applicable legal requirements and regulations. Contact your local authorities.

If the rotor or filters have been exposed to chemicals dangerous to the environment, assess the risk. Chemicals can accumulate in the material. Take necessary precautions to comply with applicable local legal requirements and regulations.

The rotor material is not combustible and should be deposited like fiberglass materials.

! WARNING: If the rotor is to be cut into pieces, wear a suitable CE-marked face mask selected and fitted according to applicable safety standards to protect from dust.

11. Contact Munters

Contact information for Munters offices worldwide, categorized by region (Europe, Worldwide).

Includes telephone numbers and email addresses for various countries.