Lennox Adnova THS, THS025, THS056, THS073, THS035 Installation, Operating And Maintenance Manual

INSTALLATION, OPERATING

AND MAINTENANCE

CEILING MOUNTED SPLIT UNIT

@DNOVA

THS

2,5 - 38 kW

www.lennoxemea.com

ADNOVA-THS_R410A-

IOM-1304-E

Index

1 General Description ............................................................................................................ 2

1.1 Structure .......................................................................................................................................... 2

1.2 Field of application ........................................................................................................................... 2

1.3 Cooling circuit .................................................................................................................................. 2

1.4 Installation warnings ........................................................................................................................ 5

2 Inspection / Transport ......................................................................................................... 6

2.1 Inspection on receipt ........................................................................................................................ 6

2.2 Lifting and transport ......................................................................................................................... 6

2.3 Unpacking ........................................................................................................................................ 6

3 Installation ........................................................................................................................... 7

3.1 THSI - Indoor unit positioning .......................................................................................................... 7

3.2 Free-cooling duct connections (optional) ......................................................................................... 8

3.3 THSC - Outdoor unit positioning ...................................................................................................... 8

3.4 Refrigerant connections ................................................................................................................... 9

3.5 Lines positioning .............................................................................................................................. 9

4 THS - Evacuation and Charging Operations.................................................................... 10

4.1 Introductions .................................................................................................................................. 10

4.2 Full vacuum and charge of the unit ................................................................................................ 10

4.3 Evacuating a circuit “contaminated” with refrigerant ...................................................................... 11

4.4 Charging positions (single poi nt) ................................................................................................... 11

5 Electrical Connections ...................................................................................................... 12

5.1 Generalities .................................................................................................................................... 12

6 Starting Up ......................................................................................................................... 14

6.1 Preliminary checks ......................................................................................................................... 14

6.2 Starting up for the first time ............................................................................................................ 14

6.3 Start up .......................................................................................................................................... 15

6.4 Starting operation........................................................................................................................... 15

6.5 Checks during operation ................................................................................................................ 16

6.6 Checking the refrigerant level ........................................................................................................ 16

7 Operating Parameters Setting .......................................................................................... 17

7.1 Generalities .................................................................................................................................... 17

7.2 Maximum pressure switch ............................................................................................................. 17

7.3 Minimum pressure switch .............................................................................................................. 17

8 Maintenance ...................................................................................................................... 18

8.1 Warnings ........................................................................................................................................ 18

8.2 Periodical checks ........................................................................................................................... 18

8.3 Repairing the cooling circuit ........................................................................................................... 20

8.4 Tightness test ................................................................................................................................. 20

8.5 Hard vacuum and drying of cooling circuit ..................................................................................... 20

8.6 Recharging with refrigerant R410A................................................................................................ 21

8.7 Environmental protection ............................................................................................................... 21

9 Troubleshooting ................................................................................................................ 22

@DNOVA THS_R410A-IOM-1304-E 1

1 General Description

Model: THS

025

035

045

056

073

090

105

120

145

310

380

230Vac ±10% / 1Ph / 50Hz

400Vac ±10% / 3Ph+N+PE / 50Hz

24Vdc ±16% (Emergency cooling)

48Vdc ±16% (Emergency cooling)

Min.

-20 °C

Max.

- - 48.0°C

46.5°C

45.0°C

47.0°C

45.0°C

44.0°C

-

45°C

47°C

conditions

Min.

19 °C / 30% R.H.

conditions

Min.

10 °C / 90% R.H.

Max.

55 °C / 90% R.H.

THS “Lennox Telecom Split” units composed by an evaporating indoor unit THSI for ceiling or wall installation and a

motor-condensing outdoor unit THSC, mainly for electronic equipped shelters, process centers, telecommunications sites
from 4.5 to 38 kW of nominal cooling capacity.

The system provides air filtration, indoor ventilation, cooling, heating, free cooling with outdoor fresh air to assure the

useful climate in the site.

1.1 Structure

All THS units have a galvanized s heet steel supporting base and enclosing panels are painted with epoxy polyester

powder coating cured at 180°C, or, on request, painted galvanized sheet steel (RALxxxx).

1.2 Field of application

All THS units are to be used within the operating limits stated in this manual (see Tab. 1); failure to comply with said

limits will invalidate the warranties provided in the contract of sale.

Tab. 1 Operating limits

Power supply

Outdoor
temperature

Temp. /
Humidity

Storage

Max.

35 °C / 50% R.H.

1.3 Cooling circuit

The entire cooling circuit is built in the Lennox factory using only components of the finest quality brands and processes

conforming to the specifications of “Directive 97/23” for brazing and testing.

Compressors

On THS units are installed only primary brand scroll compressors of leading international manufacturers.

Today scroll compressors represent the best solution in terms of reliability, efficiency and MTBF.

Cooling components

• Molecular mesh activated-alumina filter dryer.

• Flow indicator with humidity indicator (indications are provided directly on the sight glass).

• Thermostatic valve with external equalization and integrated MOP function.

• High and low pressure switches.

• Schrader valves for checks and/or maintenance.

The electric control board is constructed and wired in accordance with Directives 73/23/EEC and 89/336/EEC and

Electric control board

related standards. All the remote controls use 24V signals powered by an insulating transformer.
Note: The mechanical safety devices such as the high pressure switch are of the kind that trigger directly; their

efficiency will not be affected by any faults occurring in the microprocessor control circuit, in compliance with
97/23 PED.

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1

Compressor

7

Low pressure switch (LP)

2

Condenser

8

High pressure switch (HP)

3

Thermostatic valve

9

Condensing pressure probe

4

Evaporator

10

Tap 5 Filter dryer

11

Solenoid valve

6

Sight glass

12

Check valve

Microprocessor control

The microprocessor built into the unit allows the different operating parameters to be controlled from a set of pushbuttons

situated on the electric control board:

Switching ON/OFF of compressor to maintain the temperature set point “T” inside the shelter.

• Alarm management: - High / Low pressure;

- Dirty filters alarm;

- Air flow alarm.

• Alarm signalling.

• Display of operating parameters.

• RS232, RS485 serial output management (optional).

• Phase sequence error (Not displayed by the mP, but prevents the compressor from starting up).

See microprocessor control manual for further details, also in relation to particular customer specifications.

Fig. 1 Basic cooling circuits

THS025-035

Pos. Description Pos. Description

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Pos.

Description

Pos.

Description

1

Compressor

6

Sight glass

2

Condenser

7

Low pressure switch (LP)

3

Capillary tupe

8

High pressure switch (HP)

4

Evaporator

9

Condensing pressure probe

5

Filter dryer

10

Tap

Pos.

Description

Pos.

Description

1

Compressor

8

High pressure switch (HP)

2

Condenser

9

Condensing pressure probe

3

Thermostatic valve

10

Tap

4

Evaporator

11

Liquid receiver

5

Filter dryer

12

Flodding valve

6

Sight glass

13

Safety valve

7

Low pressure switch (LP)

14

Check valve

THS025-035

THS045-056-073-090-105-120-145-310-380

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1.4 Installation warnings

General rules

• When inst alling o r servicing the unit, you must strictly follow the rules provided in this manual, comply with the
directions on the units themselves and take all such precautions as are necessary.

• The fluids under pressure in the cooling circuit and the presence of electrical components may cause haz ardo us
situations during installation and maintenance work.

All work on the unit must be carried out by qualified personnel only, trained to do their job in
accordance with current laws and regulations.

• Failure to comply with the rules provided in this manual or any modification made to the unit without prior
authorisation will result in the immediate invalidation of the warranty.

Warning: Before performing any kind of work on the unit, make sure it has been
disconnected from the power supply.

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2 Inspection / Transport

2.1 Inspection on receipt

On receiving the unit, check that it is perfectly intact: the unit left the factory in perfect conditions; immediately report any

signs of damage to the carrier and note them on the Delivery Slip before signing it. Lennox or its Agent must be promptly
notified of the entity of the damage. The Customer must submit a written report describing every significant sign of
damage.

2.2 Lifting and transport

While th e unit is bein g unloaded and positioned, utmost care must be taken to avoid abrupt or violent maneuvers. Th e

unit must be handled carefully and gently; avoid using machine components as anchorages or holds and always keep it
in an upright position.
The unit should be lifted using the pallet it is packed on; a trans pallet or similar conveyance means should be used.

Warning: In all lifting operations make sure that the unit is securely anchored in order to

prevent accidental falls or overturning.

2.3 Unpacking

The packing must be carefully removed to avoid the risk of damaging the unit. Different packing materials are used:

wood, cardboard, nylon etc.
It is recommended to keep them separately and deliver them to suitable waste disposal or recycling facilities in order to
minimize their environmental impact.

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3 Installation

(mm)

(mm)

025-035

621.6

560

045-056-073-090-105

1021.6

560

120-145

1121.6

650

(mm)

(mm)

310 - 380

1475

445

ONLY FOR CEILING MOUNTING

A

The THS package air-conditioning unit is suitable for all environments except aggressive ones. Do not place any

obstacles near the units and make sure that the air flow is not impeded by obstacles and/or situations causing back
suction.

3.1 THSI - Indoor unit positioning

Bear in mind the following aspects when choosing the best site for installing the unit and the relative connections:

• position of the indoor unit next to the main heat source;

• location of power supply;

• solidity of the supporting ceiling / wall.

It is recommended to first prepare holes in the ceiling / wall for the screw anchors.

The dimensions and the positions of the holes for the screw anchors are shown below.

Model: THSI

Fig. 2 Service area

Model: THSI

A

A

B

B

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(mm)

(mm)

(mm)

(mm)

THSI 025-035-045-056-073-090-105-120-145-310-380

0

200

200

200

D

THSI
unit

B

THSI
unit

A

C

Model A

B

C

D

3.2 Free-cooling duct connections (optional)

The air conditioner may be supplied with an integrated free-cooling device (optional), which uses fresh air from outside to

cool the ambient without starting up the compre ss or.
The device supplies the correct cooling capacity required, through a modulating motor damper.

In this case, the back side of the unit is equipped with connections collect the outside air, as follows:

In both cases, the holes in the ceiling/wall have to be protected by rainproof grilles with pre-filter to avoid water or foreign
bodies get in the conditioner.

Outside air, taken into the room by the fan, gets out through an overpressure damper, which is installed on the ceiling /

wall of the room and is protected also by external rainproof grille.

3.3 THSC - Outdoor unit positioning

The condensing unit must be positioned outside to enable its cooling.
It is connected to the air conditioner through the refrigerant lines.

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3.4 Refrigerant connections

THIS OPERATION MUST BE CARRIED OUT BY AN EXPERT TECHNICIAN.

Keep refrigerant lines as short as possible and use the suggested diameter and the indication of the “Piping Design

Criteria” (attached to the unit documentation)

3.5 Lines positioning

Connect the air conditioner to the condensing unit by using refrigerant lines in hard or soft copper.

• Limit the number of pre shaped bends; if this is not possible, every bend must have a radius of at least 100mm.

• The gas line must be insulated.

• The liquid line must be kept far from heat sources; if this is not possible it has to be insulated.

• If the condensing unit is placed above the evaporating unit, the last segment of the intake tube (insulated tube)

must lean towards the condensing unit.

• If, on the other hand, the condensing unit is placed under the conditioner it is advisable to create a trap on the
intake tube.

The recommended sizes for the power cables and emergency line are shown in the related electrical drawings.

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4 THS - Evacuation and Charging Operati ons

P

Enthalpy h

T tank/ambient

Saturated gas

Saturated

P [Pa]

Time

200 s

6

150

This type of work must be carried out by qualified personnel only trained to do their job in
accordance with current laws and regulations.

4.1 Introductions

The simultaneous presence of liquid and vapour makes it necessary for both to be in a state of saturation ( Gibbs law ),

as shown in Fig. 3). In conditions of thermal equilibrium, the pressure in the tank corresponds to the T of the surrounding
environment; a withdrawal of refrigerant charge will cause pressure drops, which will be associated with:

• .. withdrawal of refrigerant charge: .... pres sure drop ins ide the tank;

• .. pressure drop inside the tank: ........ T drop & change of status;

• .. T drop & change of status: .. .......... evaporation of part of the liquid, causing a cooling down of the liquid;

• cooling of liquid: thermal exchange with ambient air, further evaporation of remaining liq uid;

the original pressure in the tank will be restored after a certain period of time.

Fig. 3 Gibb’s law diagram

liquid

4.2 Full vacuum and charge of the unit

Vacuum cycle

In general it is better to apply a “long” rather than a “hard” vacuum: reaching a low pressure too abruptly may in fact

cause that any remaining humidity evaporates instantaneously, thus freezing part of it.

Fig. 4 Vacuum cycle diagram

The Fig. 4 represents a vacuum cycle and an optimal subsequent pressure rise for the refrigeration devices we

manufacture. Generally in bigger refrigeration systems or if there is a suspicion of an extensive quantity of humidity in the
refrigeration circuit, the vacuum needs to be “broken” by using anhydrous nitrogen. Then the steps of evacuation need to
be repeated as described before. This operation facilitates the removal of remaining and/or frozen humidity during the
evacuation process.

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4.3 Evacuating a circuit “contaminated” with refrigerant

T oil

Pressure

% of refrigerant in oil

The first step is to remove the refrigerant from the circuit. To do this a specific machine is necessary with a drying

compressor in order to recover the refrigerant.
Refrigerants all tend to dissolve in oil (compressor sump). The Fig. 5 illustrates a specific property (Charles’ Law) of
gases, which are more soluble in liquids as the pressure increases but less soluble as the temperature increases.

Fig. 5 Charles’ law diagram

1 ) The release of refrigerant from the cooling circuit tends to cool down the oil and thus actually creates the

opposite effect by keeping more refrigerant dissolved in the oil: for this reason, it is advisable to switch on -if
available- the crankcase heate r during the evacuation process.

2 ) If a high % of refrigerant gets in contact with the Pirani gauge (vacuum sensor), it may “mislead” this sensitive

sensor and misinterpret the value for a certain period of time. For this reason, if no machine for recovering
refrigerant is available, it is nonetheless advisable to switch on the crankcase heater and to avoid full vacuum
before the circuit has been adequately purged of refrigerant. The refrigerant may in fact dissolve in the oil of the
vacuum pump, reducing its performance for a long time (hours).

4.4 Charging positions (single point)

The best position to charge the unit is the section between the thermostatic valve and the evaporator. Take care to avoid

the fixing of the thermostat bulb until the operation is completed. It is important to ensure that the valve orifice remains
open in order to allow the passage of refrigerant also towards the condenser / liquid receiver.
If possible, avoid the charge of refrigerant into the suction line of the compressor as this may cause excessive dilution of
the lubricant. In any case verify first the necessary volume of the crankcase and compare it with the required charge
volumes.

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5 Electrical Connecti ons

5.1 Generalities

Before carrying out any job on electrical parts, make sure the power supply is disconnected.

Check that the mains electricity supply is compatible with the specifications (voltage, number of phases, frequency)
shown on the unit rating plate.
The power connection for single-phase loads is to be made with a three-pole cable and “N” wire at the centre of the star
(optional: power supply w/o neutral).

The size of the cable and line protections must conform to the specifications provided in the wiring
diagram.

The supply voltage may not undergo fluctuations exceeding ±5% and the unbalance between phases must always be

below 2%.

The above operating conditions must always be complied with: failure to ensure said

conditions will result in the immediate invalidation of the warranty.

The electrical connections must be made in accordance with the information shown in the wiring diagram provided with
the unit and with current and local regulations. An earth connection is mandatory. The installer must connect the
earthing wire using the earthing terminal situated on the electric control board (yellow and green wire).
The power supply to the control circuit is taken from the power line through an insulating transformer situated on the
electric control board.
The control circuit is protected by suitable fuses or automatic breakers depending on the unit size.

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Legend:

1

= Power supply for internal unit (THSI);

2

= Power supply for external unit (THSC);

3

= Auxiliary cables.

MAIN

ELECTRICAL

PANEL

2

1

3

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6 Starting Up

T oil

% of R410A in oil

Pressure

6.1 Preliminary checks

• Check that the electrical connections have been made properly and that all the terminals are securely tightened.
This check should also be included in a periodic six-month inspection.

• Check that the voltage at the RST terminals is 230± 5% or 400 V ± 5% and make sure the yellow indicator light of
the phase sequence relay is on. The phase sequence relay is positioned on the electric control board; if the
sequence is not duly observed, it will not enable the machine to start.

• Make sure there are no refrigerant leaks that may have been caused by accidental impacts during transport
and/or installation.

• Check the power supply to the crankcase heating elements (where present).

The heating elements must be turned on at least 12 hours before the unit is started.
They are automatically activated when the main switch is put on. Their function is to raise the T of
the oil in the sump and limit the quantity of refrigerant dissolved in it.

To verify whether the heating elements are working properly, check the lower part of the compressors: it should be warm

or in any case at a temperature 10 - 15 °C higher than the ambient temperature.

Fig. 6 Charles’ law diagram

The diagram above illustrates a specific property of gases (Charles’ Law), which are more soluble in liquids as the

pressure increases but less soluble as the temperature increases: if the oil in the sump is held at a constant pressure, an
increase in temperature will significantly reduce the amount of refrigerant dissolved in it, thus ensuring that the desired
lubricating function is maintained.

6.2 Starting up for the first time

Instructions for THSI units and THSC units

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Refrigerant connection between two units (THSI + THSC)

• THSI and THSC units are both pre-charged with nitrogen.

• Following here-attached refrigeration diagram instructions (pay attention in particular to IN/OUT) start refrigeration

connections between THSI and THSC units.

• Make the vacuum in refrigerant line between in/out of the two units.

main

m_on_off

Comp OFF T

int

00.0 °C

UNIT ON:

Evap OFF T

sup

00.0 °C

No

Cond OFF T

ext

00.0 °C

Master

Ev 00000 Comp 00000 h

STAND ALONE UNIT

Electrical connection

• Open the frontal panel of the two units.

• Turn THSI unit QS main switch OFF.

• Switch OFF THSC unit Q01 automatic switch.

• Insert the power supply cable using one of the special holes you can find on THSI unit sides and connect it to QS

main switch.

• Following wiring diagram instructions make electrical connections between THSI and THSC units power supply
and power supply and auxiliary circuit cables.

• Connect user interface to microprocessor J10 connector (you can find it in THS wiring diagram) using a telephone
cable.

• Turn THSI unit QS main switch ON.

• Turn THSC unit Q01 automatic switch ON.

• Charge the circuit with R410A refrigerant.

• Close the panels with the matching screw s.

6.3 Start up

When you give power to microprocessor, you can see the first mask of main menu where you can see the following

information:

• Indoor air temperature (T

• Supply air temperature (T

• External air temperature (T

• Compressors and fans state;

• Counter for evaporator fans and compressors.

);

int

);

sup

) (only Freecooling version);

ext

In next mask (m_on_off), that you can see pushing Down

, it is possibile to turn the unit on or off pushing Enter

, Down and then again Enter . It is also shown if the unit is a master or a slave unit (this is a fundamental

information for LAN operations) and configuration of local net address (Unit 1, Unit 2 or Stand Alone).

In THSI unit there is a RED coloured LED to show that alarm is present

Usage

D Always consult the “USER MANUAL” and control system manual provided with the unit when undertaking

maintenance and/or advanced set-ups.

D N.B.: In THSI unit there is not condensing pressure gouge so the value is not reliable.

6.4 Starting operation

Before starting the unit, turn the main switch on, select the operating mode desired from the control panel and press the

”ON” button on the control panel.

If the unit fails to start-up, check if the service thermostat has been set according to the nominal values

provided.

You should not disconnect the unit from the power supply during periods when it is inoperative
but only when it is to be taken out of service for a prolonged period (e.g. at the end of the season).

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6.5 Checks during operation

Check the phase sequence relay on the control board to verify whether the phases occur in the correct sequence: if

they do not, disconnect the unit from power supply and invert two phases of the incoming three-pole cable.
Never attempt to modify internal electrical connections: any undue modifications will immediately invalidate the
warranty.

6.6 Checking the refrigerant level

After a few hours of operation, check whether the liquid level indicator has a green ring: a yellow colour indicates the

presence of humidity in the circuit. In such a case the circuit must be dehumidified by qualified personnel.

Large quantities of bubbles should not appear through the liquid level indicator. A constant passage of numerous

bubbles may indicate that the refrigerant level is low and needs to be topped up.

Make sure the overheating of the cooling fluid is limited to between 5 and 8 °C: to this end:

1 ) read the temperature indicated by a contact thermometer placed on the compressor intake pipe;
2 ) read the temperature indicated on the scale of a pressure gauge likewise connected to the intake side; refer to

the pressure gauge scale for the refrigerant R410A.
The degree of overheating is given by the difference between the temperatures thus determined.

Make sure that the Sub-cooling of the cooling fluid is limited t o betw een 3 and 5°C, to this end:

1 ) read the temperature indicated by a contact thermometer placed on the condenser outlet pipe;
2 ) read the temperature indicated on the scale of a pressure gauge connected to the liquid inlet at the condenser

outlet; refer to the pressure gauge scale for the refrigerant R410A.
The degree of Sub-cooling is given by the difference between the temperatures thus determined.

Warning: All THS units are pre-charged with nitrogen. Any top-ups must be made using the

same type of refrigerant. This operation is to be considered extraordinary
maintenance work and must be performed by qualified personnel only.

Warning: The refrigerant R410A requires “POE“ polyolester oil of the type and viscosity
indicated on the compressor rating plate.
For no reason should oil of a different type be introduced into the oil circuit.

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7 Operating Parameters Setting

Differential air pressure switch (outlet air flow)

Pa

50

30

Differential air pressure switch (dirty filter)

Pa

50

20

Maximum pressure switch

Bar

42.0

4.0

Manual

Minimum pressure switch

Bar

2.0

1.5

Automatic

Modulating condensation control device

Bar

18.0

7.0

-

Time lapse between two compressor starts

s

480 - -

7.1 Generalities

All the control devices are set and tested in the factory before the unit is dispatched. However, after the unit has been in

service for a reasonable period of time you can perform a check on the operating and safety devices.
The settings are shown in Tab. 4 and Tab. 5.

All servicing of the equipment is to be considered extraordinary maintenance and may be carried out

BY QUALIFIED TECHNICIANS ONLY: incorrect settings may cause serious damage to the
unit and injuries to persons.

The operating parameters and control system settings configurable by means of the microprocessor control are
password protected if they have a potential impact on the integrity of the unit.

Tab. 4 Setting of control devices

Control device Set point Differential

Values to be calibrated depending on the appl i cat i on.

Tab. 5 Setting of safety-control devices

Control device Activation Differential Resetting

7.2 Maximum pressure switch

The high pressure switch stops the compressor when the outlet pressure exceeds the set value.

Warning: Do not attempt to change the setting of the maximum pressure switch: Should the
latter fail to trip in the event of a pressure increase, the pressure relief valve will open.

The high pressure switch must be manually reset; this is possible only when the pressure falls below the set differential
(see Tab. 5).

7.3 Minimum pressure switch

The low pressure switch stops the compressor when the inlet pressure falls below the set value for more than 120

seconds. The switch is automatically reset when the pressure rises above the set differential (see Tab. 5).

@DNOVA THS_R410A-IOM-1304-E 17

8 Maintenance

Check the efficiency of all the control and safety devices.

Once a year

replaced whenever they show signs of deterioration.

Check the refrigerant level by means of the liquid level indicator.

Every 6 mos.

Check the efficiency of the differential air pressure switch and dirty filter differenti al pressure switch.

Every 6 mos.

Check the condition of the air filter and replace it if necessary.

Every 6 mos.

green as shown on the indicator sticker, replace the filter.

The only operations to be performed by the user are to switch the unit On and Off.

All other operations are to be considered maintenance work and must thus be carried out by qualified personnel trained
to do their job in accordance with current laws and regulations.

8.1 Warnings

All the operations described in this chapter MUST ALWAYS BE PERFORMED BY QUALIFIED
PERSONNEL ONLY.

Before carrying out any work on the unit or accessing internal parts, make sure you have
disconnected it from the mains electricity supply.

The upper part and the outlet pipe of the compressor reach high temperatures. Be especially
careful when working in the surrounding area with the panels off.

Be especially careful when working in proximity to finned coils since the 0.11 mm thick aluminium
fins can cause superficial injuries due to cuts.

After completing maintenance jobs, always replace the panels enclosing the units and secure them
with the fastening screws provided.

8.2 Periodical checks

To guarantee a constantly satisfactory performance over time, it is advisable to carry out routine maintenance and

checks as described below. The indications below are related to standard tear and wear.

Tab. 6 Periodical checks

Operation Frequency

Check the terminals on the electric control board and compressor terminal boards to ensure that they are
securely tightened. The movable and fixed contacts of the circuit breakers must be periodically cleaned and

Once a year

Check the humidity indicator (green = dry, yellow = humid) on the liquid level indicator; if the indicator is not

@DNOVA THS_R410A-IOM-1304-E 18

Every 6 mos.

Fig. 7 Inspecting the air filter

Remove the grilled panel to access the damper and air filter compartment.

Remove the damper fastening screws placed at the side.

Pull out the entire damper section to access the servomotor.

Grilled panel

Servomotor

Remove the grilled panel to access the damper and air filter compartment.

Pull out the air filter.

Check the condition of the filter and replace it if necessary.

Air filter

Grilled panel

Fig. 8 Inspecting the damper servomotor

@DNOVA THS_R410A-IOM-1304-E 19

8.3 Repairing the cooling circuit

Wa rning: While performing repairs on the cooling circuit or maintenance work on the compressors,

make sure the circuit is left open for as little time as possible. Even if briefly exposed to air, ester oils
tend to absorb large amounts of humidity, which results in the formation of weak acids.

If the cooling circuit has undergone any repairs, the following operations must be carried out:

• tightness test;

• evacuation and drying of the cooling circuit;

• charging with refrigerant.

If the system has to be drained, always recover the refrigerant present in the circuit using suitable
equipment; the refrigerant should be handled exclusively in the liquid phase.

8.4 Tightness test

Fill the circuit with anhydrous nitrogen supplied from a tank with a pressure-reducing valve until the pressur e rises to 22

bar.

During the pressurization phase, do not exceed a pressure of 22 bars on the compressor low
pressure side.

The presence of any leaks must be determined using special leak detectors. Should any leaks be detected during the
test, empty out the circuit before repairing the leaks with suitable alloys.

Do not use oxygen in the place of nitrogen as a test agent, since this would cause a risk of
explosion.

8.5 Hard vacuum and drying of cooling circuit

To achieve a hard vacuum in the cooling circuit it is necessary to use a pump capable of generating a high degree of

vacuum, i.e. 150 Pa of absolute pressure with a capacity of approximately 10 m
evacuation will normally suffice to achieve an absolute pressure of 150 Pa.
If there is no such vacuum pump available, or whenever the circuit has remained open for long periods of time, you are
strongly recommended to adopt the triple evacuation method. This method is also recommended when there is a
presence of humidity within the circuit. The vacuum pump should be connected to the inlets.

The procedure to be carried out is as follows:

• Evacuate the circuit until you reach an absolute pressure of at least 350 Pa: at this point inject nitrogen into the
circuit until you reach a relative pressure of about 1 bar.

• Repeat the step described above.

• Carry out the step described above for the third time, but in this case attempting to reach the hardest vacuum

possible.

Using this procedure you can easily remove up to 99% of pollutants.

3

/h. If such a pump is available, one

@DNOVA THS_R410A-IOM-1304-E 20

8.6 Recharging with refrigerant R410A

• Connect the tank of refrigerant gas to the male 1/4 SAE inlet situated on the liquid line after discharging a little
gas to eliminate air in the connection pipe.

• Fill with refrigerant in liquid form until you reach 75% of the total charge.

• Then connect to the inlet on the pipe between the thermostatic valve and evaporator and complete the charging

process with the refrigerant in liquid form until no more bubbles can be seen on the liquid level indicator and
the operating parameters specified in section 7 have been reached.

A unit that was originally charged with (nitrogen) in the factory must not be charged with
R22 or other refrigerants without the written authorization Lennox

8.7 Environmental protection

The law implementing the regulations (reg. EEC 2037/00) which govern the use of ozone-depleting substances and

greenhouse gases bans the dispersal of refrigerant gases in the environment and requires whoever is in their
possession to recover them and, at the end of their useful life, either to return them to the dealer or take them to a
suitable waste disposal facility. The refrigerant HFC R410A is not harmful to the ozone layer but is included among the
substances responsible for the greenhouse effect and thus falls within the scope of the aforesaid regulations.

Therefore, special care should be taken when carrying out maintenance work to minimize
refrigerant leaks.

@DNOVA THS_R410A-IOM-1304-E 21

9 Troubleshooting

FAULT

POSSIBLE CAUSES

CORRECTIVE ACTIONS

auxiliary circuits.

The electronic card is cut off from the power supply.

Check the fuses.

restart the unit.

disconnecting them upstream from the unit.

manufacturer.

section ventilation circuit.

Check whether the condenser coil surface is obstructed.

Check the condensation control device (optional).

with sub-cooling values exceeding 5 °C.

Pa and then recharge in the liquid phase.

more than 8 °C.

abnormally low pressure.

pressure

replace it.

should not exceed 2°C. If they do, replace the filter.

(where present).

cooling; if it is below 2°C replenish the charge.

restoring power.

One of the HP or LP pressure switches has tripped.

Check on the microprocessor, eliminate the causes.

compartment.

e-panel (down flow units) and clean it.

Unit is not perfectly level

Place correctly the unit.

On this pages you will find a list of the most common reasons that may cause the package unit to fail or any malfunction.

This causes are broken down according to easily identifiable symptoms.

You should be extremely careful when attempting to implement any of the possible remedies
suggested: overconfidence can result in injuries, even serious ones, to inexpert individuals.
Therefore, once the cause has been identified, you are advised to contact the manufacturer or a
qualified technician for help.

Tab. 7 Fault-Causes-Corrections

The unit does

not start

The compressor

is noisy

Presence of

abnormally

high pressure

Low

condensation

No power supply.

Alarms have been released.

The phase sequence is wrong.

The compressor is rotating in the wrong direction.

Insufficient airflow through the condenser.

Presence of air in the refrigerant circuit, as revealed
by the presence of bubbles in the flow indicator also

Unit overcharged, as revealed by a Sub-cooling of

Thermostatic valve and/or filter obstructed. These
symptoms may also occur in the presence of an

Transducer fault.

Malfunctioning of thermost ati c va l ve .

Check if power is being supplied both to the primary and

Check whether any alarms are signalled on the
microprocessor control panel, eliminate the causes and

Invert two phases in the primary power line after

Check the phase sequence relay. Invert the phases on the
terminal board after disconnecting the unit and contact the

Check for the presence of obstructions in the condenser

Drain and pressurise the circuit and check for leaks. Evacuate
slowly (for more than 3 hours) until reaching a pressure of 0.1

Drain the circuit.

Check the temperatures upstream and downstream from the
valve and filter and replace them if necessary.

Check the efficiency of the condensation control device
(optional).

Warming the bulb with your hand, check whether the valve
opens and adjust it if necessary. If it does not respond,

Low evaporation

pressure

The compressor

does not start

Water out from

the unit

Filter dryer clogged.

Low condensation temperature.

Low level of refrigerant.

The circuit breakers or line fuses have been tripped by
a short circuit.

The phases have been inverted in the distribution

The drain pan hole is closed.

The siphon is missing. Check for the presence and provide for a new one.

@DNOVA THS_R410A-IOM-1304-E 22

Pressure drops upstream and downstream from the filter

Check the efficiency of the condensation control device

Check the refrigerant level by measuring the degree of Sub-

Pinpoint the cause by measuring the resistance of the
individual windings and the insulation from the casing before

Check the phase sequence relay.
Open the front panels, remove the sheet metal just below the

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Due to LENNOX EMEA ongoing commitment to quality, the specifi cations, ratings and
dimensions are subject to change without notice and without incurring liability.
Improper installation, adjustment, alteration, service or maintenance can cause property
damage or personal injury.
Installation and service must be performed by a qualifi ed installer and servicing agency.

www.lennoxemea.com

ADNOVA-THS_R410A-

IOM-1304-E