FläktGroup DENCO - OFFICECool LECU Operating instructions

Brand: FläktGroup

Model: DENCO - OFFICECool LECU

Type: Operating instructions

DENCO ®-OFFICEcool - LECU

OPERATION MANUAL

Table of Contents DENCO®-OFFICEcool - LECU

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1 Overview and system description. . . . . . . . . . . . . . . . . . . . . . . . . 5

1.1 Type range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1.2 System overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2 Safety and user information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.1 Availability of the operation manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.2 Operating manual content . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

2.3 Symbols used . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.4 Safety symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.5 Safe work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.6 Proper use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.7 Modifications and changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.8 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.9 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.10 Personnel selection and qualification . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3 Technical description and the scope of supply. . . . . . . . . . . . . 13

3.1 LECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.2 Scope of supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

3.3 Control system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.4 Control accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3.4.1 Operating limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

3.4.2 Control strategy LECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.5 Technical data LECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.5.1 Electric details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3.5.2 Dimensional drawings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

4 Transport and storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.1 Shipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.2 Transportation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

4.3 Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

5 Assembly. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.1 Mechanical installation of the LECU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

5.1.1 Positioning, mounting and aligning the LECU . . . . . . . . . . . . . . . 20

5.2 Filter maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

5.3 General noise level assessment on site . . . . . . . . . . . . . . . . . . . . . . . . . . 22

6 Electrical connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.1 Connecting controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

6.2 Connecting network cables to the Zone Unit . . . . . . . . . . . . . . . . . . . . . . 24

6.3 LECU Control System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

6.4 Network cable for connecting LECUs . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

7 Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

7.1 General information on operating the unit . . . . . . . . . . . . . . . . . . . . . . . . . 27

7.2 LECU control system operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

7.2.1 LECU modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

7.2.2 Description of LECU operation . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

7.3 Remote ACQUA terminal operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

DENCO®-OFFICEcool - LECU Table of Contents

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8 Failure detection and troubleshooting . . . . . . . . . . . . . . . . . . . 32

8.1 Local environment control unit failure . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

9 Servicing and maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

9.1 Replacing the filter and cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

10 Dismantling and disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

10.1 Dismantling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

10.2 Disposal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Declaration of Conformity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

The reproduction, distribution and utilization of this document as well as the communication of its contents to others

in the event of the grant of a patent, utility model or design.

Typecode DENCO®-OFFICEcool - LECU

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The following type coding contains an exact description of the configuration of a unit.

Complete the following boxes according to the unit's type code in the documentation:

LECU sales code D LE

Unit type

Product

Configuration

Model size

Fan

Heating

Controls

Grille

Filter

Electric heating

DDenco

LE LECU

MMaster unit

SSlave unit

ANo control

230 230 mm height

EEC motor fan

SAC motor fan

HElectric heater

NNot fitted

DDisplay

NNot fitted

CCircular

RRectangular

NNot fitted

2G2 filter

NNot fitted

EEURO plug

UUK plug

S3-pin socket

NNot fitted

DENCO®-OFFICEcool - LECU Overview and system description

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 5

1 Overview and system description

We would like to thank you for purchasing this product.

The DENCO®-OFFICEcool range uses the latest environmentally friendly and energy-

saving technology. It has a compact and clean-style design and its high performance

and quality meets the demands of today's offices.

The units are intended for indoor installation to provide cooling, heating, dehumidifica-

tion, humidification and filtration of air at atmospheric pressure. The entire unit was

designed and produced in conformity with the ISO 9001 quality assurance system and

a control system ensuring the achievement of faultless conditions. The unit provides

the ease of installation and maintenance, each component is designed to guarantee

maximum reliability, operating economy and a long service life.

1.1 Type range

– LECU (Local Environment Control Unit) fan unit for controlling a local environment

to be installed in a 600 mm x 600 mm opening in the floor.

– Installation height 230 mm and 140 mm

– 240 V power supply

– A fully modulating damper

– A 3-speed fan (AC), a stepless speed control fan (EC) or a 0-10V control DC fan

– A self-extinguishable plastic or metal casing, certified as hygienic

– Electric heating (optional)

1.2 System overview

Fig. 1-2: Return without a suspended ceiling

Fig. 1-3: Return with a suspended ceiling

Fig. 1-1: LECU 230

(display optional)

TOP RETURN SYSTEM

Raised Modular Floor

CEILING RETURN SYSTEM

Overview and system description DENCO®-OFFICEcool - LECU

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Fig. 1-4: Bottom-up flow of conditioned air

The flexible DENCO®-OFFICEcool underfloor air conditioning system operates very

economically. When installed in new buildings, it significantly shortens the construction

time and reduces building costs.

The System Conditioned air from the zone unit (1) enters the space underneath the raised floor (2)

and then appropriately located LECUs (3). Temperature and flow rate through the

LECUs under the floor can be controled by each user.

Typically, the zone unit is set to a minimum outlet air temperature of over 12°C to eli-

minate the feeling of cold. As room temperature depends on the LECU's set point set-

ting, the LECU’s damper opens to control heat gain or loss within air flow.

The Zone Unit continuously controls temperature under the floor according to the

zone's requirements based on time settings or temperature or humidity sensor

readings.

A strategically located return air sensor controls the adjustment of air volume by the

Zone Unit, chilled water and the two- or three-way valves, the heating water valve

(if used), electric heating elements (if used), DX cooling or heating (if used) and the

humidifier (if used).

As the average temperature of air returning to the Zone Unit differs from the set point

setting, the air flow rate increases. Simultaneously, cooling or heating is activated as

needed.

The operation of the Zone Unit can also be controlled based on the average of readings

from the sensors of the LECUs in the zone. This ensures that the system operates with

the maximum volumetric flow rate of air only during peak-load times, which do not

occur very frequently in most offices.

Air returns to the Zone Unit either through the unit's top or the inlet grilles in the sus-

pended ceiling.

In conditions without load when the required conditions in the room have been

reached, the unit only runs with a minimum flow rate (usually approximately 25% of the

maximum).

When the required conditions change, the maximum and minimum flow rate from the

Zone Unit can be easily adjusted.

BOTTOM-UP FLOW, BOTTOM RETURN

ZONE UNIT

The zone unit automatically controls the volumetric flow rate

of air to provide sufficient heating or cooling of the environ-

ment at floor level.

The zone unit can be installed in or outside of the room to be

heated or cooled; for maintenance only access from the

front is required.

UNDERFLOOR BARRIER

A silicon-impregnated, easy-to-shape material for forming

channels for air return to the zone unit. This system allows

covering offices having complex design forms.

The barriers are easy to move from place to place and modify

to meet requirements for the office layout..

DENCO®-OFFICEcool - LECU Overview and system description

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 7

Bottom return Conditioned air from the Zone Unit enters the distribution ducts between the floor bear-

ing structure and the raised floor. The distribution ducting for air supply and return are

separated from the floor bearing structure as well as the raised floor by insulation and

can be modified if needed.

Typically, the zone unit is set to a minimum outlet air temperature of over 12°C to eli-

minate the feeling of cold.

Appropriately located LECUs control local conditions by controlling the volume of air

leaving the underfloor ducting and mixing with air in the room. As room temperature

depends on the LECU's set pointsetting, the LECU’s damper opens to control heat gain

or loss with air flow. Temperature under the floor is continuously controlled by the Zone

Unit so that the requirements set for each zone are met.

A strategically located return air sensor controls the flow rate through the Zone Unit,

the two-way chilled water valve, the heating water valve (if used), electric heating

elements (if used), DX cooling or heating (if used) and the humidifier (if used).

As the average temperature of air returning to the Zone Unit differs from the set point

setting, the air flow rate increases. Heating and cooling valve control takes place simul-

taneously. This ensures that the system operates with the maximum volumetric flow

rate of air only during peak load times, which do not occur very frequently in most

offices. In conditions without load when the required conditions in the room have been

reached, the unit only runs with a minimum flow rate.

Under these conditions the air supplied to the underfloor space is partially directed into

the room by the LECUs but primarily returns to the Zone Unit through a small duct

below the raised floor. Under normal operating load conditions the line of return air

grilles enables to take the used air from the room and back to the Zone Unit.

When the conditions required change, the maximum and minimum floor rate from the

Zone Unit can be easily adjusted.

Positioning LECUs The LECUs can be fast and easily moved anywhere along the raised floor space. They

are connected using a power supply and network cable, easy to plug into any power

supply or data system under the floor. The structural design of the raised floor provides

easy maintenance and servicing access.

Safety and user information DENCO®-OFFICEcool - LECU

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2 Safety and user information

This is an original operation manual verified by the manufacturer.

DENCO®-OFFICEcool air conditioning units are designed in accordance with unique

technological and engineering standards and in compliance with accepted safety

principles.

FläktGroup units must be operated in perfect technical condition and for the purpose

intended, with operators observing the operating manual and being aware of safety

risks!

It must be understood that failing to comply with instructions contained in this

operating manual may lead to a malfunction of the unit, health risks and damage of

property. An authorized professional must repair all defects immediately!

2.1 Availability of the operation manual

This operation manual contains important information regarding safe and correct oper-

ation of the FläktGroup unit.

This manual must always be available at the site where unit is operating. Every person

working on the equipment must read this manual fully before commencing the work

and take all relevant information while performing a task into account.

The operation manual is intended to be used by fitting and installation companies,

building services engineers, technical personnel or trained persons as well as electrical

and refrigeration engineering specialists.

2.2 Operating manual content

This operation manual covers points on the following areas:

– Assembly/disassembly

– Installation

– Commissioning

Operation See information on operating the unit in the controller manual.

Maintenance and

troubleshooting

This chapter is concerned with maintenance, defect detection and troubleshooting.

Error messages and controller codes are specified in the respective manual for the

controller.

Damage to the unit!

In the case of alarms and faults always make sure that the cause of the fault is

investigated. In particular, multiple resetting of alarms without rectifying the cause

can lead to an extended unit damage and in such a way shall result in invalidation

of the warranty.

Note!

This manual applies to the configurations of the unit as shown in our

standard catalogue.

In the case of special configurations we reserve the right to change the

units’ parameters which may not be included in the current document, see

chapters 1 and 3.

DENCO®-OFFICEcool - LECU Safety and user information

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 9

2.3 Symbols used

The following symbols are used to highlight parts of text in this document:

– This symbol is used to indicate a standard list.

•This symbol indicated instructions that must be kept to.

This symbol indicates the result of an activity.

2.4 Safety symbols

Note!

Additional detailed information on using your FläktGroup unit can be found here.

Recycling!

This symbol points out proper procedure for recycling of package material and

disused unit components. These assembly groups need to be separated according

to their material type (e.g. metal, plastic etc.)

Use safety boots!

This symbol points out that you must wear proper boots.

Use safety gloves!

This symbol points out that you must wear proper gloves.

Use safety goggles!

This symbol indicates the mandatory use of safety goggles.

Personal injury!

This symbol indicates a risk of electrical shock that can result in serious injury,

death and material damage.

Danger of electrical current!

This symbol indicates a risk of electrical shock when carrying out certain job(s).

Hot surface danger!

This symbol covers instructions on preventing personal injury due to hot surfaces.

Risk of accident due to hot liquids!

This section covers instructions on preventing personal injury due to hot liquids.

Danger – Sharp gutting edges!

Specific information on rules and restrictions for the prevention of personal injuries

due to cutting on thin metal fins is presented in this section.

High pressure hazard!

Here you can find special information as well as rules and restrictions for the

prevention of personal injuries due to high pressure.

Safety and user information DENCO®-OFFICEcool - LECU

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2.5 Safe work

When working in the power supply area:

For all jobs:

Danger due to low temperatures!

Here you can find special information, rules and restrictions regarding the preven-

tion of personal injuries due to escaping liquid refrigerants.

Danger due to overhead loads!

This symbol warns you about personal injury and damage caused by overhead

loads.

Risk of rotating unit parts!

This section points out particular instructions as well as rules and restrictions for

preventing personal injury as aresult of rotating unit parts.

Environmental damage!

This symbol warns about damage to the environment and turns your attention to

all current national environmental protection regulations and codes.

Danger due to toxic substances!

This symbol warns you about dangers due to toxic substances.

Damage to the unit!

Here you will find special information, rules and restrictions regarding the preven-

tion of damage to the FläktGroup unit.

Danger of damage due to static discharge!

This symbol warns about risk of static discharge-related damage to the unit.

Danger of electrical current!

Disconnect all electric power of the unit and ensure the power cannot be inadver-

tently energized, earth, short-circuit and block off all neighbouring live parts. Non-

compliance can lead to death or serious injury.

Personal injury!

Glycols and other antifreeze agents are harmful for humans and animals, if swallo-

wed. Consult a doctor immediately if swallowed by mistake.

Light oil is applied to some bare metal parts as a protective coating and this could

cause dermatic reaction to sensitive skin.

High pressure hazard!

When working on hydraulic or in case of damage to the components or piping,

there is a risk of injury from fluids or gases escaping at high pressure. Exercise due

caution and attention when carrying out this work.

DENCO®-OFFICEcool - LECU Safety and user information

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 11

•Observe instructions for the installation and transport of the unit.

•Observe commissioning requirements.

•Always check that only authorized and trained engineering personnel are allowed

access to the unit. If necessary, use suitable devices to prevent unauthorized

persons from accessing the unit.

•Any leaks must be immediately repaired by the FläktGroup service centre or a

cooling equipment specialist.

•Observe warnings on the unit's safety labels.

2.6 Proper use

DENCO®-OFFICEcool units are designed for indoor installation and connection to a

chilled water system and intended to provide the cooling, heating, humidification (optio-

nal), drying and filtration of air at atmospheric pressure.

Proper use also includes observing the operating manual of the controller and conduc-

ting inspection and maintenance as required by FläktGroup.

Improper use Any other use than that described above is deemed improper. The manufacturer /

supplier has no liability for damage resulting from improper use. Any risk is borne solely

by the user.

2.7 Modifications and changes

Modifications or changes to the FläktGroup unit are permitted only after prior consulta-

tion with and approval by FläktGroup Sales. Any work not mentioned in this manual is

subject to consultation with and approval by FläktGroup. Failure to do so terminates

the validity of the CE marking and warranty.

2.8 Spare parts

Only original FläktGroup spare parts are allowed, since FläktGroup is not liable if third-

party spare parts are used. The spare part list is enclosed with the unit documentation.

Environmental damage!

Do not pollute the environment with liquid products. Dispose of the latter in

accordance with local laws and regulations by avoiding harm to the environment.

Ethylene glycol and propylene glycol are in Water Hazard Class 1 (slightly water

endangering) of the catalogue of water-endangering substances. This also applies

to mixtures with water.

Danger due to toxic substances!

When using an open flame during work with the hydraulic system avoid contact

with flammable surfaces.

Touching electric insulation, panel insulation, electric cables, vinyl coatings, paint

coatings and rubber or plastic parts with an open flame releases toxic products of

combustion. Therefore, it is necessary to provide sufficient ventilation in the work-

place when using flames or heat sources.

Personal injury and material damage!

FläktGroup units must not be operated:

– in explosion risk areas;

– in areas with strong electromagnetic fields, (electromagnetic immunity as of

EMC Directive; refer to the Declaration of Conformity in the unit documenta-

tion)

– in environment with high levels of air contamination,

– in environments with corrosive and/or aggressive air.

Safety and user information DENCO®-OFFICEcool - LECU

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2.9 Disposal

Operating substances and media must be disposed of safely and ecologically accord-

ing to the material type; see Chapter 10.2 Disposal.

2.10 Personnel selection and qualification

Each person working with the FläktGroup unit must read the operating manual in its

entirety. This document must be read before commencing each activity, not while

already conducting it.

Connection to the power supply must be done by qualified personnel or authorized pro-

fessionally trained specialist with experience in the following fields:

– Occupational health and safety principles

– Accident prevention regulations

– Regulations and standards with accepted work procedures.

Each worker must be able to assess the requirements of the work task, evaluate

related risks and take measures to prevent them.

DENCO®-OFFICEcool - LECU Technical description and the scope of supply

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 13

3 Technical description and the scope of supply

Directives and regulations The LECU complies with the following directives and regulations:

– Directive on Machinery 2006/42/EC

– Low Voltage Directive 2006/95/EC

– Electromagnetic Compatibility 89/336/ECC + 2004/108/EC

– The unit’s documentation includes:

– This operating manual with all relevant data concerning the unit being supplied

– Connection diagram

– Declaration of conformity

– Optional accessories

3.1 LECU

General

LECUs provide air conditioning systems with a unique ability to deal with changing

requirements for spatial arrangements. The LECU is an intelligent fan unit which can

be installed anywhere within a raised floor. The LECU maintains the locally required

temperature level by mixing air from the room with conditioned air from the space

below the floor according to the settings. If necessary, the unit can be optionally

equipped with electric heating. The LECU is able to operate independently and does

not require any cable connection to the Zone Unit; however, the units connected to the

network can be run using a controller (remote access for setting operating points and

monitoring operating indicators.

The connection layout of a LECU is shown in the following diagram. It includes a motor-

controlled mixing damper, an electric heater (optional) and a fan. The unit is installed

in a raised floor. Temperature control under the floor is provided by the Zone Unit. The

outlet and return air grilles are located in the top section of the unit, with the underfloor

air supply connection from the side. The damper is fully controlled by an actuator.

Fig. 3-2

3.2 Scope of supply

Controller The 230 mm heigh LECU has a black plastic frame, as a standard with fire resistance

Class ABS UL94-V0 (self-extinguishing).

The two aluminium alloy grilles at the top of the LECU are flush with the raised floor

surface and are generally designed for offices. One of the grilles takes air away from

the room while the other supplies air into it. Ratio of return air from the room and con-

ditioned air from the underfloor void is controlled by the fully modulating damper using

commands from the controller.

Fig. 3-1: LECU

(The display optional)

Electric Heater Thermal trip

DI1

Electric Heater

DO3

AO1

DO1 and DO2

AI2 Fan DO5

AI1

AI3

Option

Technical description and the scope of supply DENCO®-OFFICEcool - LECU

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LECU dimensions Overall LECU dimensions are 595 mm x 596mm x 230 mm, the frame in the raised

floor structure is 600 mm x 600 mm. Each grille is 200 mm x 600 mm and can be sup-

plied in a design that it is flush with the surface and blends with the type of flooring. The

grilles are fully adjustable and allow levelling off differences in floor thickness of up

to 12 mm.

Control damper The damper is controlled by a fully modulated actuator which uses commands from the

controller, opens or shuts the damper and allows the supply of air from the underfloor

space into the room. The control damper includes a secondary manually adjustable

damper which is set during installation and allows the continuous supply of air from the

underfloor space even under conditions when the primary damper is fully closed due

to climatic conditions.

Fan The unit has a radial fan directly driven by an AC or EC electric motor. A built-in thermal

protection device with automatic reactivation after closing is installed as a standard.

Filter (optional) G2 filter in sheet metal frame.

Electric heating element

(standard installation)

The unit is optionally fitted with a 500 W electric heating element. The element includes

a protection thermostat for automatic disconnection when high temperature is reached

with automatic reactivation.

Fig. 3-3: Fan

Fig. 3-4: Filter G2

Fig. 3-5: Electric heating

element

DENCO®-OFFICEcool - LECU Technical description and the scope of supply

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 15

3.3 Control system

General All LECU’s functions are performed by the Carel control system installed in the unit.

The LECU can be set in various ways. The easiest one is to set the required setpoint

using the infrared remote control or built-in display. The setpoint can be accessed

through a BMS (Building Management System) which makes all access points availa-

ble through the intranet. The LECU typically works as an independent unit and does

not require connection to the Zone Unit. The LECU’s set point can be accessed either

locally, from a building management system or through the intranet. The LECU is typ-

ically supplied in three versions, either as an independent unit or with network controls

in a "Master / Slave" configuration (master / slave unit).

The controls principle in the two systems is identical. This allows the remote monitoring

and setting of each set point and control parameter of the LECU.

Local environment

control unit

The LECU is controlled by a microprocessor controller with all necessary control pro-

cedures required. The configuration is selected by entering the parameter using the

integrated display.

Temperature control The LECU has two air temperature sensors for measuring the temperature in the room

and the temperature under the raised floor. The intelligent controlled operates the

damper, adjusting the supply of cool air underneath the floor or warm air from the room

to maintained the required conditions in the room.

3.4 Control accessories

Display The optional LED Display enables manual adjustments of temperature set point, fan

speed and on/off operation of the LECU.

For further information and utilization please refer to chapter 7.2 „LECU control system

operation“.

Remote ACQUA terminal Remote ACQUA terminal used to set the operation of the e-drofan electronic controller.

It also contains a built-in NTC probe for measuring the room temperature and the con-

nected devices. This probe is used by the unit/units for air-conditioning the zone.

Finally, it can be used to set the parameters and display the status of the unit.

For further information and utilization please refer to chapter 7.3 „Remote ACQUA

terminal operation“.

Fig. 3-6: LCD Display

(optional)

Fig. 3-7: ACQUA display

Technical description and the scope of supply DENCO®-OFFICEcool - LECU

16 FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications

3.4.1 Operating limits

Control sequence graph

Fig. 3-8 Control sequence graph

LECU - AC fan (underfloor temp. > set point) = constant air flow/ variable temperature

LECU - AC fan (underfloor temp. < set point) = constant air flow/ variable temperature

set

point

underfloor temperature (B2)

set

point

DENCO®-OFFICEcool - LECU Technical description and the scope of supply

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 17

3.4.2 Control strategy LECU

Cooling mode If the return air sensor detects temperature that is higher than the operating point, and

underfloor temperature is lower than that of return air, the damper opens as shown in

the chart to cool the room down.

Heating mode If the return air sensor detects temperature that is lower than the operating point, and

underfloor temperature is higher than that of return air, the damper opens as shown in

the chart to heat the room.

Electric heater mode The electric heating element turns on when return air temperature in the room drops

below the proportionality band of the damper / electric heating element as shown in the

chart.

Regulation of set point The default factory setting of the LECU’s temperature set point is 22 °C. The set point

can be easily set either directly on the LECU using the handheld IR controller or display

(optional) or through the Zone Unit network, BMS or intranet. The set point setting tol-

erance is ±2 °C.

Variation of the fan speed There are three fan levels with an AC motor or a fan with an EC motor (with variable

speed control in 10 levels) available. The medium speed level is selected as initial

speed. The fan’s set point can be set either directly on the LECU using through the

Zone Unit network, BMS or intranet.

3.5 Technical data LECU

Under floor pressure 0 (Pa)

* NOTE : This data relates only to “re-circulation mode and should not be used for system design purposes.

* Underfloor air discharge mode air volumes will be related to underfloor air pressure. Contac FläktGroup

for further technical information.

3.5.1 Electric details

at 230 V, 1 Ph + N / 50 Hz

Fan Speed Air volume flow Sound power

air

dB(A)

Underfloor pressure [Pa]

0 5 10

m3/s m3/hr m3/s m3/hr m3/s m3/hr

10.084 302 0.09 317 0.092 331 18

20.11 369 0.113 407 0.117 421 25

30.14 504 0.142 511 0.144 518 31

LECU AC LECU EC

Fan Current [A] 0.5 0.5

Capacity [W] 35 40

Electric Heater Current [A] 2.2 2.2

Capacity [W] 500 500

Unit without Heater Fitted Current [A] 0.5 0.5

Capacity [W] 35 40

Unit with Heater Fitted Current [A] 2.7 2.7

Capacity [W] 535 540

Technical description and the scope of supply DENCO®-OFFICEcool - LECU

18 FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications

3.5.2 Dimensional drawings

Fig. 3-9

DENCO®-OFFICEcool - LECU Transport and storage

FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications 19

4 Transport and storage

4.1 Shipment

When the shipment arrives, check it for completeness according to the shipping docu-

mentation and for any damage caused during transport.

If any damage is found, take pictures of the components affected.

4.2 Transportation

•For personal safety, wear gloves and protective boots when moving the unit.

•When suspending the unit standing on a pallet, use a spacer so that the unit does

not get squeezed

•Before transporting the unit make sure that all mounting parts are anchored and

secured.

•Only use lifting devices with a sufficient load rating.

•Never use damaged lifting equipment.

•Ropes or chains must not be knotted or in contact with sharp edges.

•Only use ropes or chains of identical length.

•Use certified lifting devices.

•Move the unit carefully, avoiding sudden movements.

•Lower the unit gently without impact.

•If necessary, use a specialist firm to transport the unit.

4.3 Storage

Permitted storage conditions / permitted conditions for units not yet installed

Air temperature: -20 °C to +50 °C

Air humidity: up to 90 % (relative humidity with no condensation)

Note!

Transport insurance claims regarding missing parts or damage caused by trans-

port can only be made if such damage is confirmed by the forwarder.

Note!

We recommend keeping the original packaging to provide protection and facilitate

handling in subsequent transport and storage. Only remove the original packaging

immediately before installation.

If the unit is to be stored for a prolonged period of time before installation or com-

missioning, its parts must be protected against damage due to dust and dirt!

Damage to unit and personal injury!

In order to avoid injuries and damage use appropriate lifting equipment such as a

crane for lifting and handling.

When tying or lifting using a forklift truck or a truck hydraulic arm, the unit must be

safeguarded so as not to topple over.

The unit’s weight is specified in the order documentation and on the unit's identifi-

cation plate.

Danger due to overhead loads!

Never walk under a suspended load as there is a risk of untying or detachment

from the hoist. Failure to do so may lead to serious or fatal injuries.

Assembly DENCO®-OFFICEcool - LECU

20 FläktGroup DC-2013-0103-GB 2022-11/R3 • Subject to modifications

5 Assembly

5.1 Mechanical installation of the LECU

•Be careful when lifting the unit as its weight is approximately 25 kg.

•The unit must be in a vertical position in two mutually perpendicular planes and rest

on the supports (legs) of the raised modular floor. If that is not the case, problems

might occur during operation.

5.1.1 Positioning, mounting and aligning the LECU

•The LECU is to be installed in a 600 mm x 600 mm opening in the floor. Remove a

tile from the modular floor and replace it with the LECU.

•If necessary, remove the edge strips.

•Set the LECU into the raised floor.

•Lean the LECU base frame against the adjoining floor panel.

Now tilt the LECU by approximately 20° into the raised floor.

Fig. 5-1

Notes on assembling and installing the unit!

Information on the assembly and installation of the unit is provided here. The posi-

tioning, installation and assembly of the unit must be conducted by qualified per-

sonnel or an authorized and professionally trained specialist experienced in this

field and familiar with occupational health and safety regulations.

Information on moving the unit from place to place!

If the FläktGroup unit has been moved from another location, it is necessary to

commission it again as described in chapter “Commissioning”.

Note!

For the detailed plan of positioning the unit follow the dimension diagram in the

unit’s documentation.

Attention!

FläktGroup is not liable for damage caused by improper handling during the instal-

lation of the unit.

Rest Structural Frame

Against Adjacent Floor Pane

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FläktGroup DENCO - OFFICECool LECU Operating instructions

FläktGroup DENCO - OFFICECool LECU Operating instructions

FläktGroup DENCO - OFFICECool LECU Operating instructions

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