CLIMAVENETA ACCURATE, AXO, AWO, AWU, AXU User & Maintenance Manual

GB

USER AND MAINTENANCE MANUAL

precision air-conditioners

ACCURATE

Direct expansion

Direct expansion

AXO air outlet from the top
AXU air outlet from the bottom

Water-cooled

AWO air outlet from the top
AWU air outlet from the bottom

frame 1: 07-10

frame 2: 15-18

frame 3: 20-26-29

frame 4: 39-30-40-50

frame 5: 55-60-70

1

English 01/07

ACCURATE AX* - AW*

INDEX

General characteristics 2

Unit configuration 2

Air flows 5

Rating plate 6

General technical data 6

Commissioning and testing 8

Operation and control 9

Instruments and alarms 10

Calibrating the control and safety devices 11

Calibrating the pressure control valve 11

Calibrating the air flow sensor 12

Calibrating the dirty filter sensor 12

Temperature and humidity probe 13

Servomotor and hot water valve 13

Electrical specifications 14

Maintenance 15

Electric heaters 17

Tightening the drive belts 17

Humidifier 18

Terminal and board configuration 19

Troubleshooting 19

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

U I A

AIU

In some parts of this manual, the following symbols are

used:

WARNING = for actions that require special
care and suitable preparation

PROHIBITED = for actions that absolutely
MUST NOT be performed

A

I

U

The following symbols are used in this publication and inside the unit:

User

Installer

Assistance

Important

Prohibition

Specialist personnel

(electrician)

Person with in-depth knowledge
and experience such as to be
able to recognise risks and avoid
dangers that may derive from
electricity (IEV 826-09-01).

ACCURATE AX* - AW*

2

English 01/07

DOCUMENTS

DOCUMENTS ENCLOSED WITH THE UNIT

Each unit is delivered complete with the following documents:

• Air-conditioner installation manual;

• Air-conditioner user and maintenance manual;

• Instruction manual for the microprocessor controller;

• Wiring diagram;

• List of spare parts;

• CE declaration with list of European directives and standards
that the unit is compliant with;

• Warranty conditions.

AIU

DIRECT EXPANSION UNIT CONFIGURATION

AIU

12345678910111213141516171819202122

AXO2 9ME

RANGE A ACCURATE air-conditioner Climaveneta Version

L Air-cooled “LT” (low temperature)

VERSION W Water-cooled

X Air-cooled

COMPRESSORS AND CIRCUITS

B N° 2 Compressors N° 2 Circuits
M N° 1 Compressor N° 1 Circuit

C Centrifugal direct traction (standard from 07 to 18 kw)

E EC Inverter fans high efficiency
P Centrifugal direct traction high ESP, 3 speeds (from 07 to 18 kw)

FANS T Centrifugal V-belts ESP 20 Pa (from 21 to 88 kw)

U Centrifugal V-belts ESP 50 Pa (from 21 to 88 kw)
X Centrifugal V-belts ESP 100 Pa (from 21 to 88 kw)
Y Centrifugal V-belts ESP 150 Pa (from 21 to 88 kw)
Z Centrifugal V-belts ESP 200 Pa (from 21 to 88 kw)

VOLTAGE

M 230 V 1Ph+N 50Hz
T 400 V 3Ph+N 50Hz

B Over (intake from the bottom)

AIR FLOW O Over (intake from the front)

R Over (intake from the rear)
U Under (intake from the top)

07 Frame 1 (7 kw)
10 Frame 1 (10 kw)
15 Frame 2 (15 kw)
18 Frame 2 (18 kw)
20 Frame 3 (20 kw)
26 Frame 3 (26 kw)

FRAME/POTENZA 29 Frame 3 (29 kw)

30 Frame 4 (30 kw)
39 Frame 4 (39 kw)
40 Frame 4 (40 kw)
50 Frame 4 (50 kw)
55 Frame 5 (55 kw)
60 Frame 5 (60 kw)
70 Frame 5 (70 kw)

Digit 1

Digit 2

Digit 3

Digit 4-5

Digit 6

Digit 7

Digit 8

FLUID + 0 R407 C

CONDENSER 1 R407 C + pressostatic valve x condenser control

CONTROL 3 R22

4 R22 + pressostatic valve x condenser control

Digit 9

type

digit

exe

0 Semi-graphic user terminal on the unit

CONTROL 1 Without user terminal

2 Semi-graphic user terminal + wall mounting kit

Digit 10

ACCURATE AX* - AW*

3

English 01/07

THERMOSTATIC VALVE

0 Mechanical thermostatic valve
1 Electronic thermostatic valve

0 No post-heating
1 STD heaters with 3 steps

HEATING 3 Hot water post-heating coil

4 Hot water post-heating coil + STD heaters with 3 steps
6 Hot gas post-heating coil

7 Hot gas post-heating coil + STD heaters with 3 steps

0 No humidity and condensate management
1 Probe for humidity reading only
2 Humidifier

HUMIDITY CONTROL 4 Dehumidification with partial coil operation

6 Humidifier + Dehumidification / part coil
8 Humidifier + Dehumidification / part coil + condensate drain pump
9 PPump for draining the condensate and/or the steam cylinder

0 No board
A Clock board

B RS485 board
C RS232 board (GSM modem)
D Ethernet board

ELECTRONIC BOARDS E LON board

F Trend board
G Clock board + RS485 board
H Clock board + RS232 board

L Clock board + Ethernet board
M Clock board + LON board
N Clock board + Trend board

0 No sensor

1 Dirty filter sensor

2 Fire sensor

3 Smoke sensor

SENSORS

4 Fire + smoke sensor

5 Fire + smoke + flooding sensor

6 Flood sensor

7 Dirty filter + fire + smoke sensor

8 Dirty filter + flood sensor

9 Dirty filter + fire + smoke + flood sensor

0 Class 0 panels (A1-DIN 4102)

1 Class 1 panels STD insulation

HEAT AND SOUND 2 Class 1 panels soundproof insulation

INSULATION 3 Class 0 panels (A1-DIN 4102) + soundproofing hoods on the compressors

4 Class 1 panels STD insulation + soundproofing hoods for compressors

5 Class 1 soundproofed panels + soundproofing hoods for compressors

0 No damper

1 Pressure-relief damper (Over units only)

DAMPERS 2 Motor-driven damper

3 Motor-driven damper with spring return,in view

4 Motor-driven damper + side panel

5 Motor-driven damper + rwith spring return + side panel

2 Air filter with EU2 efficiency

4 Air filter with EU4 efficiency

AIR FILTER

5 Air filter with EU5 efficiency

6 Air filter with EU2 efficiency + air change filter

7 Air filter with EU4 efficiency + air change filter

8 Air filter with EU5 efficiency + air change filter

PACKAGING

0 Thermoplastic perimeter protection + cardboard lid

1 Wooden crate

EXTRAS

0 No extras requested

S No Digit for request

Digit 11

Digit 12

Digit 13

Digit 14

Digit 15

Digit 16

Digit 17

Digit 18

Digit 19

Digit 20

4

English 01/07

ACCURATE AX* - AW*

AW*AX*

AIR-COOLED DIRECT EXPANSION UNIT - VERSION
AX*

Refrigerant circuit

All models have a single refrigerant circuit, and in some cases two
circuits.
See the DIGIT on the previous page.
The compressor pumps the hot refrigerant gas into the outdoor
condenser.
The liquid refrigerant then flows to a liquid receiver installed in
the indoor unit, to ensure a constant flow of refrigerant to the
thermostatic valve and subsequently the evaporator.
Here the liquid refrigerant absorbs the heat from the environ­ment and changes state, becoming a gas, then returning to the
compressor: the cycle is then repeated.
To ensure the correct discharge pressure of the refrigerant, the
outdoor condenser is fitted as standard with fan speed control.
Valves for isolating the refrigerant circuit are supplied as standard
to assist the routine maintenance operations.
The Scroll compressor is fitted with a non-return valve to pre­vent the migration of liquid from the outdoor condenser in the
summer, and unwanted flows of refrigerant during start-up.
A second non-return valve, to be fitted by the installer, is recom­mended during operation in winter, to prevent the migration of
the refrigerant charge from the liquid receiver to the outdoor
condenser, with consequent low pressure alarms.

Air-cooled condenser, outdoor installation

The indoor unit can be connected to different types of outdoor
condensers, standard or low noise versions, with special treat­ments on the coils.
For the corresponding information refer to the manual on out­door air-cooled condensers.

Note 1: the outdoor units and condensers are supplied separately
Note 2: the indoor unit is delivered charged with nitrogen at near

atmospheric pressure.The outdoor condenser, on the other hand,
is supplied pressurised with dry air (around 3 bar.)
Note 3: the customer is considered responsible for making the
correct connections between the indoor and outdoor unit, as
clearly indicated in the Installation manual, and for ensuring the gas
and oil charges, where necessary.

WATER-COOLED DIRECT EXPANSION UNIT - VER­SION AW*

Refrigerant circuit

All models have a single refrigerant circuit, and in some cases two
circuits.
See the DIGIT on the previous page.
The compressor pumps the hot refrigerant gas into the indoor
condenser made from braze welded steel plates.
The liquid refrigerant then flows to a liquid receiver installed in
the indoor unit, to ensure a constant flow of refrigerant to the
thermostatic valve and subsequently the evaporator.
Here the liquid refrigerant absorbs the heat from the environ­ment and changes state, becoming a gas, then returning to the
compressor: the cycle is then repeated.
To ensure the correct discharge pressure of the refrigerant, the
outdoor condenser is fitted as standard with fan speed control.
Valves for isolating the refrigerant circuit are supplied as standard
to assist the routine maintenance operations.
The Scroll compressor is fitted with a non-return valve to pre­vent the migration of liquid from the outdoor condenser in the
summer, and unwanted flows of refrigerant during start-up.
A second non-return valve, to be fitted by the installer, is recom­mended during operation in winter, to prevent the migration of
the refrigerant charge from the liquid receiver to the outdoor
condenser, with consequent low pressure alarms.

Water condenser

The units are fitted with an internal braze welded steel plate heat
exchanger.
During installation, a pressure control valve should be fitted
(available in the price list) to manage the condensing pressure.
(See the User and Maintenance Manual)
This circuit works with primary water or with a closed circuit
connected to an external Dry Cooler or an evaporative tower.
For “closed” circuits, the water should be mixed with antifreeze
to prevent frost during the winter, with consequent damage to
the systems: see the installation manual to calculate the required
percentage of antifreeze fluid.
The Dry Coolers are supplied as an accessory (see the price list),
while the antifreeze fluid and fluid circulating pump are generally
supplied by other companies.
For “open” circuits, mechanical filters are required to protect
against impurities and prevent the braze welded plate heat
exchanger from blocking.
To reduce energy consumption (pump), a valve should be fitted to
close the circuit when the indoor unit is off.
Note 1: the water-cooled indoor units (AW*) come with the
refrigerant circuit completely charged and tested in the factory
before being delivered.

5

English 01/07

ACCURATE AX* - AW*

AIR FLOWS

AI

The ACCURATE air-conditioners are available in different con-
figurations, based on the air intake and outlet positions; the main
distinction is between OVER and UNDER units.
The versions defined as OVER with air outlet from the top gene-

rally have the air intake at the front, rear and/or from the bottom,
as required by the customer, and the air outlet from the top of
the unit, in ducts, false-ceilings, or from outlet plenums at the
front.

fig. 1

fig. 2

fig. 3

fig. 4

1 OVER units with intake from the front and outlet plenum 2 OVER units with intake from the front and outlet from the

top

3 OVER units with intake from under the floor and outlet from

the top

4 OVER units with intake from the rear and outlet from the top

5 UNDER units with intake from the top and front outlet

plenum.

6 UNDER units with intake from the top and outlet under the

floor

The versions defined as UNDER with air outlet from under the
floor have the air intake through the top of the unit directly from
the environment, or via ducts and/or intake plenums.

fig. 5

fig. 6

AXO - AWO

AXU - AWU

6

English 01/07

ACCURATE AX* - AW*

The air-conditioner rating plate is positioned on a panel inside
the unit, and provides the following information:

- Model and serial number of the unit;

- Power supply (voltage, phases and frequency);

- Power input of the unit and the individual components;

- Current input of the unit and the individual components: OA
(Operating current), FLA (Full load current) and LRA (Locked
rotor current);

- Settings of the pressure switches in the refrigerant circuit (HP
and LP);

- Type of refrigerant (R407C/R22);

- Charge or pre-charge in each refrigerant circuit (AW* ver­sions only)

RATING PLATE

AIU

MODEL SERIAL NUMBER

CODE
COOLING CAPACITY kW
POTENZA TERMICA kW
PRESSIONE MASSIM bar
ALIMENTAZIONE ELETTRICA DI POTENZ V - ~ - Hz
ALIMENTAZIONE ELETTRICA AUSILIARI V - ~ - Hz
POTENZA ELETTRICA MAX. ASSORBIT kW
CORRENTE MAX. ASSORBIT A
CORRENTE DI SPUNT A
GRADO DI PROTEZIONE IP X 4
SCHEMA ELETTRIC N°
PESO IN FUNZIONAMENT kg
ANNO DI FABBRICAZIONE

GENERAL TECHNICAL DATA

AIU

Total cooling capacity (1) kW 7,2 10 15 18 20,8 26,6 29,5
Sensible cooling capacity (1) kW 7,2 9,1 14,6 17,5 20,8 25,6 27
SHR (1) 1 0,91 0,97 0,97 1 0,96 0,91
Total cooling capacity (2) kW 6,8 9,1 13,5 16,2 18,9 24,2 26,6
Sensible cooling capacity(2) kW 6,8 8,7 13,3 16 18,9 23,7 25,2
SHR (2) 1 0,95 0,98 0,99 1 0,98 0,95
No. of compressors

n°1111111

Total power input

kW 1,72 2,52 3,83 4,4 5,05 6,75 7,65
N° circuits n° 1111111
Air flow-rate mc/h 2400 2400 4900 4800 6500 8000 8000
No. of fans

n°1122111

Total power input

kW 0,49 0,49 0,9 0,9 1,8 2,2 2,2
ESP (3) Pa 20 20 20 20 20 20 20
Noise level (5) 49 51 55 55 55 56 56
Standard power supply V/ph/Hz 400/3+N/50
Width mm 600 1000
Depth mm 500 790
Height mm 1980

ARC outdoor condenser 014m 014m 021m 025m 030m 040m 040m

Total cooling capacity (1) kW 39,4 30,2 40,5 50,4 55,8 61,6 70,6
Sensible cooling capacity (1) kW 39,4 30,2 40,5 48,4 55,8 61,6 65
SHR (1) 1 1 1 0,97 1 1 0,92
Total cooling capacity (2) kW 35,8 27,5 36,8 45,4 50,8 56 63,6
Sensible cooling capacity (2) kW 35,8 27,5 36,8 45 50,8 56 60,4
SHR (2) 1 1 1 0,99 1 1 0,95
No. of compressors

n°1222222

Total power input

kW 9,75 7,66 10,1 13,5 13,1 15,6 19,6
N° circuits n° 1222222
Air flow-rate mc/h 13500 10500 13500 13500 19000 19000 19000
No. of fans

n°2222333

Total power input

kW43,244666
ESP (3) Pa 20 20 20 20 20 20 20
Noise level (5) 57 54 56 56 57 57 57
Standard power supply V/ph/Hz 400/3+N/50
Width mm 1550 2100
Depth mm 790
Height mm 1980

ARC outdoor condenser 052m 042b 051b 077b 077b 088b 93b

ACCURATE AX air cooled 07 10 15 18 20 26 29

ACCURATE AX air cooled 39 30 40 50 55 60 70

1 - 24°C-50%, 35°C ext
2 - 20°C-50%, 35°C ext

3 - Standard centrifugal fans
5 - measured at 1,5 m haight and 2 m front in free field

7

English 01/07

ACCURATE AX* - AW*

Total cooling capacity (1) kW 7,5 10 15 18,9 20,8 27,4 30,8
Sensible cooling capacity (1) kW 7,5 9,1 14,6 17,2 20,8 26 27,6
SHR (1) 1 0,91 0,97 0,9 1 0,95 0,9
Total cooling capacity (2) kW 6,8 9,1 13,5 17 18,9 24,7 27,4
Sensible cooling capacity (2) kW 6,8 8,7 13,5 16,5 18,9 24,2 26,1
SHR (2) 1 0,95 1 0,97 1 0,98 0,95
No. of compressors

n°1111111

Compressor power input

kW 1,68 2,52 3,83 4,15 5,05 6,2 7,2
N° circuits n° 1111111
Air flow-rate mc/h 2400 2400 4900 4800 6500 8000 8000
No. of fans

n°1122111

Fans power input

kW 0,49 0,49 0,9 0,9 1,8 2,2 2,2
ESP(3) Pa 20 20 20 20 20 20 20
Noise level (5) 49 51 55 55 55 56 56
Water flow-rate (1) l/h 1570 2150 3250 3975 4455 5780 6540
Pressure drop Dp (1) kPa 12 19,5 11 10,8 13 14 17,9
Water content l 0,66 0,66 1,16 1,53 1,53 1,77 2,2
Standard power supply V/ph/Hz 400/3+N/50

Width mm 600 1000
Depth mm 500 790
Height mm 1980

ADC outdoor condenser 013 013 025 025 030 038 051

Total cooling capacity (1) kW 39,4 30,2 42 50,4 58 61,6 70,6
Sensible cooling capacity (1) kW 39,4 30,2 42 48,4 58 61,6 68,4
SHR (1) 1 1 1 0,97 1 1 0,97
Total cooling capacity (2) kW 35,8 27,5 38,3 45,4 52,8 56 63,6
Sensible cooling capacity (2) kW 35,8 27,5 38,3 45 52,8 56 63
SHR (2) 1 1 1 0,99 1 1 0,93
No. of compressors

n°1222222

Compressor power input

kW 9,75 7,66 9,4 13,1 12,6 15,6 19,6
N° circuits n° 1222222
Air flow-rate mc/h 13500 10500 13500 13500 19000 19000 19000
No. of fans

n°2222333

Fans power input

kW43,244666
ESP (3) Pa 20 20 20 20 20 20 20
Noise level (5) 57 54 56 56 57 57 57
Water flow-rate (1) l/h 8465 2x3260 2x4420 2x5460 2x6070 2x6640 2x7760
Pressure drop Dp (1) kPa 24,1 10,5 13 15,9 15,5 18,3 21,8
Water content l 02,8 2x1,16 2x1,53 2x1,77 2x2,2 2x2,2 2,5,6
Standard power supply V/ph/Hz 400/3+N/50

Width mm 1550 2100
Depth mm 790
Height mm 1980

ADC outdoor condenser 062 078 078 078 078 092 102

ACCURATE AW water cooled 07 10 15 18 20 26 29

ACCURATE AW water cooled 39 30 40 50 55 60 70

1 - 24°C-50%, water IN / OUT 30°-35°c
2 - 20°C-50%, water IN / OUT 30°-35°c

3 - standar centrifugal fans
5 - measured at 1,5 m haight and 2 m front in free field

8

English 01/07

ACCURATE AX* - AW*

COMMISSIONING PROCEDURE
Arm the cutout in the auxiliary circuits;
Arm all the cutouts on the electrical panel;

Power up the air-conditioner electrical panel and close the main
disconnecting switch on the unit (position 'I');
Check that the control board is powered; Check that both the
LEDs relating to the phase sequence relay (RSF) are on; the yellow
LED indicates power, the green LED indicates that the sequence of
phases is correct.
If the green LED is off, disconnect power supply from the units,rever­se two phases of the power cable and restart the commissioning pro­cedure.
(In the units with sump heaters)
After having powered up the air-conditioner, wait at least 12 hours
before starting so as to suitably heat the oil in the compressors.
During extended shutdown there may be spontaneous migration of
refrigerant to the compressor sump,which at the start may cause the
oil to foam and consequent damage due to insufficient lubrication.
As a result, do not disconnect power during weekly pauses;
Open the on-off valves in the refrigerant circuits and check that the
air-cooled remote condensers are connected (air-cooled models);
Check that the external radiators are connected and make sure there
is water flow for cooling (water-cooled models);
Check that the sections of corrugated pipe with the function of drain

trap (both inside and outside of the air-conditioner) have been filled
with water during installation.

AT LEAST 12 HOURS AFTER POWER UP:
Start the air-conditioner using the buttons on the user terminal;
If an alarm is activated refer to the controller instruction manual.

COMMISSIONING AND TESTING

AIU

EMPTYING THE REFRIGERANT CIRCUIT AND
CHARGING WITH REFRIGERANT

The water-cooled units (AWO, AWU) are already charged with
refrigerant, either R407C or R22 (check the rating plate on the
unit and the compressors to see which type of refrigerant is

used).
The air-cooled units (AXO, AXU) are pre-charged with nitrogen
to prevent moisture from entering the circuit; in this case, the
refrigerant charge must be completed by the installer, following
the instructions shown in this paragraph.

R22 R407C

Open any valves in the unit or in the system to ensure that all the components are involved in the emptying operation;

Connect a high efficiency vacuum pump to the Schrader fittings or to the 1/4” SAE fittings on the compressor suction and discharge side;

Connect a cylinder of refrigerant to the charge fittings.
Empty the lines, ensuring an absolute pressure of less than 100
Pa (0.7 mm Hg) for an extended period, so as to remove the air
and any traces of moisture.

Empty the lines, ensuring an absolute pressure of less than 10 Pa
(0.07 mm Hg) for an extended period, so as to remove the air
and any traces of moisture.

The circuit should be emptied slowly and maintained for an extended period, rather than performed too quickly.

Wait 100 seconds and check that the absolute pressure does not rise above 200 Pa.

Break the vacuum by pre-charging from the cylinder of R22
refrigerant.

Break the vacuum by pre-charging from the cylinder of R407C

refrigerant in the liquid phase.
After having started the compressor, complete the charge slowly, until the pressure stabilises in the lines and the gas bubbles disappear
from the flow indicator;

Refrigerant Type of oil

R22 (Mineral oil) Suniso 3 GS White oil

R407C (POE) Mobil EAL Arctic 22 CC ICIEMKARATE RL 32S CF

The charge must be checked at the environmental design conditions
and with a discharge pressure of around 18 bar (equal to a saturated
temperature of 48°C); for units with on-off condenser control, par­tially close the intake to stop the condenser fan from repeatedly
starting-stopping.
Make sure that the subcooling of the liquid at the thermostatic valve
intake is between 3 and 5°C less than the condensing temperature
read on the pressure gauge and that the superheating of the vapour
at the evaporator outlet is around 5 °C.
The charge must be checked at the environmental design conditions

and with a discharge pressure of around 18 bar (equal to a dew

point of 48°C and boiling point of 43°C); for units with on-off con-

denser control, partially close the intake to stop the condenser fan

from repeatedly starting-stopping.

Make sure that the subcooling of the liquid at the thermostatic valve

intake is between 3 and 5°C less than the condensing temperature

read on the pressure gauge and that the superheating of the vapour

at the evaporator outlet is around 5 °C.

9

English 01/07

ACCURATE AX* - AW*

CALIBRATING THE THERMOSTATIC VALVE
(air-cooled models)

The thermostatic valve is calibrated using the adjustment screw
shown in the figure; in the water-cooled models, the correct cali­bration is already performed in the factory.

• Check that the subcooling of the liquid at the condenser
outlet is around 3-5°C;

• Check that the thermostatic valve superheating value is cor­rect (around 5 °C);

• Check that the valve sensor bulb is correctly positioned, secu­red and insulated.

If the superheating is above the value indicated previously, open
the valve further; if it is lower, close the valve further.

NOTE: the thermostatic valve must only be calibrated by
specialist personnel.

OPERATION AND CONTROL

AIU

WATER-COOLED UNITS
Water in an open circuit

If the temperature of the cooling water is not controlled and may
fall below 25°C, a pressure control valve is required (available as
an accessory) for each condenser; in this case, the supply pressu­re must not be less than 200 kPa (2 bar).
IMPORTANT: do not use water cooled using an evaporative
tower, as the condensers will rapidly become fouled by lime scale.

Water in a closed circuit

The condensers on the units are supplied with water pumped in
a closed circuit and cooled by external radiators; check that the
cross-section of the pipes and that the characteristics of the cir­culating pump are suitable: an insufficient water flow-rate affects
the performance of the air-conditioner.
The temperature of the cooling water must be controlled so as
to not fall below 25°C, preferably according to the diagram
shown in the figure.

IMPORTANT: the cooling water must contain a percen­tage of ethylene glycol (passivated and consequently non­corrosive) according to the minimum expected outside
temperature.
In the Energy Saving models, the use of glycol is always
required.

-4°C -10°C -17°C -25°C -37°C

10% 20% 30% 40% 50%

Freezing point (°C)

Percentage of ethylene glycol by weight

B

C

A

25 °C

adjustment screw

10

English 01/07

ACCURATE AX* - AW*

The pressure test points for the air flow (F3) and dirty filter (F4)
differential pressure switches are connected in parallel; (on OVER
units)

- the positive pressure test point is located on the right-hand
side of the base of the unit;

- the negative pressure test point is located in a position for
measuring the pressure upstream of the fan;(on UNDER units)

- the positive pressure test point is located behind the electrical
panel, upstream of the air filter;

- the negative pressure test point is located in a position for
measuring the pressure upstream of the fan;

Pressure
test point

Pressure
test point

Pressure
test point

Pressure
test point

RIGHT-HAND SIDE

RIGHT-HAND SIDE

FRONT OF
THE UNIT

FRONT OF
THE UNIT

Q.E.

Q.E.

INSTRUMENTS AND ALARMS

AIU

The air-conditioner is fitted with the following instruments:

- High pressure switch/switches F1 with manual reset (one
on each refrigerant circuit);

- Low pressure switch/switches F2 with automatic reset
(one on each refrigerant circuit);

- Air flow sensor F3 and dirty filter sensor F4 (differential
pressure switches);

- Temperature sensor BT2 (versions C and T) or room temper­ature and humidity sensor BH1 (on the units with humidity
control);

Some versions, in addition, have the following sensors:

- Safety thermostat TH1 (in the versions with electric
heaters), with the reset button accessible on the right-hand
side of the electrical panel.

In addition, the following optional devices may be available:

- Flood sensor made up of:
a) FSD device to be inserted in the special socket on the elec-

trical panel;

b) FLOE sensor (or sensors, connected in parallel) to be posi-

tioned at the points monitored;

- Fire and smoke sensors SFFS and SFFF;

- Hot water temperature sensor, for reading and enabling
post-heating with hot water;

- Outlet air limit temperature sensor (BT1), installed as
described in the "Installation manual".

1

2

3

4

5

6

7

8

9

10

11

12

13

1 main board
2 disconnecting switch
3 electric heaters
4 radial fan and inverter
5 compressor
6 dewatering filter
7 liquid valve
8 flow indicator
9 thermostatic valve
10 humidifier
11 dehumidification valve
12 hot water coil valve
13 temperature-humidity probe

11

English 01/07

ACCURATE AX* - AW*

CALIBRATING THE PRESSURE CONTROL VALVE

AIU

(option available for water-cooled models)

The pressure control valve, by managing the flow of water, pre­vents the condensing pressure from lowering excessively and, at
the same time, saves water consumption.
If necessary, calibrate the pressure control valve using the adjust­ment knob (the pressure is increased when turning clockwise)
until the condensing pressure stabilises at the recommended
value of 17 bar (equivalent to a saturated temperature of around
45°C when using R22), measured using a pressure gauge connect­ed to the pressure test point on the outlet valve.

1
2
3
4
5

CALIBRATING THE CONTROL AND SAFETY DEVICES

AIU

After starting the air-conditioner, make the following adjustments

- Room temperature (cooling and heating set point).

- Relative humidity (set point for humidification and dehumidifi­cation);

- Dirty filter differential pressure switch: see the paragraph on
"CALIBRATING THE DIRTY FILTER SENSOR".

The calibration values of the control and safety devices must not
be altered.

Symbol Description

F1 High pressure switch
F2 Low pressure switch

TH1 Safety thermostat (versions T and H)

Symbol Activation Differential Reset

F1 28 bar (opening) - Manual reset
F2 1,5 bar (opening) 1.5 bar 2.5 bar (automatic)

TH1 320 °C (opening) - Manual reset

12

English 01/07

ACCURATE AX* - AW*

CALIBRATING THE AIR FLOW SENSOR

AIU

The differential pressure switch F3 must be activated if the fan is
not working (when there is one fan) or one of the fans is not
working.
The factory calibration of the differential pressure switch to con­trol the air flow (F3) is 0.5 mbar (=50Pa).
As the difference in pressure between the fan intake and outlet
depends on the air flow-rate, the instrument may need to be
recalibrated after installation, checking that the contact closes
when the fan is operating normally.

To calibrate the pressure switch:

• simulate a fault in the fan system (stop the fan - if there is just
one - or one of the fans on the unit) and check that the pres­sure switch is activated;

• if the device is not activated, progressively increase the calibra­tion value of the pressure switch.

To calibrate the pressure switch, remove the plastic cover (A) by
unscrewing the two screws (B).
Use the adjustment screw (E) to calibrate the differential pres­sure switch on a scale from 0.5 to 4.0 mbar (50 to 400Pa).
If having to replace the pressure switch, unscrew the two fasten­ing screws (D), remove the rubber hoses connected to the pres­sure test points (+) and (-) and remove the electrical cables con­nected to terminals 1, 2 and 3.
To install the new pressure switch, perform the same operations
in the reverse order, inserting the cables from point (C).

+-

A

mbar

B

B

1

3

2

mbar

D

C

D

E

CALIBRATING THE DIRTY FILTER SENSOR

AIU

The factory calibration of pressure switch F4 is 3 mbar (=300Pa).
Pressure switch F4 must be calibrated according to the pressure
drop, which depends not only on the filter being dirty, but also on
the air flow-rate.
The calibration must be performed with a clean filter, as follows:

- switch the unit on

- progressively cover the surface of the air filter and make sure
that the pressure switch is activated when around 50-60%
covered;

- if the device is not activated, progressively reduce the calibra­tion of the pressure switch;

- if the device is activated too early, increase the calibration.

Pressure test points

13

English 01/07

ACCURATE AX* - AW*

WARNING: Disconnect power before working on the
servomotor

On the units with ACCURATE controllers the position of the
servomotor is proportional to the control voltage, between 0
and 10 Vdc.The servomotor stops:

- automatically at the end of its travel;

- in the position of equilibrium, corresponding to the control
voltage;

- in the current position, when cutting off power.

OPERATION OF THE MVX57 - 0-10V SERVOMOTORS

The opening of the valve can be controlled by checking the posi­tion using the indicator located on the top of the servomotor

EMERGENCY MANUAL OPERATION

The valve can be operated manually, in the event of faults to the
servomotor or the control system, using the manual control
knob located near the servomotor.

TEMPERATURE AND HUMIDITY PROBE

AIU

The figure shows the optional temperature and humidity probe.
If having to replace the probe, release the white plastic cover by
pressing point (A) with a screwdriver or a pointed object; lift the
cover (B) to access the fastening screws (C) and the terminals
(D).

For the probe electrical connection use a shielded cable; the con­nections to the terminals on the board are shown on the wiring
diagram.

126 mm

80

A

B

H

TU

O

M

T

TUO

+

C

D

Shielded cable
inlet

Fastening
holes

SERVOMOTOR AND HOT WATER VALVE

AIU

2

IN

OUT

14

English 01/07

ACCURATE AX* - AW*

Vers. B R H T

Main Switch

mod. V/ph/Hz kW FLA kW FLA kW FLA kW FLA Amp Power.

TOTAL UNIT POWER INPUT

POWER INPUT OF THE INDIVIDUAL COMPONENTS

values for individual fan

07 400/3N/50 2,47 7,95 6,47 25,45 4,72 17,75 6,47 25,45 80 6
10 400/3N/50 3,22 9,85 7,22 27,35 5,47 19,65 7 27,35 80 6
15 400/3N/50 5,02 18,1 13,02 53,1 8,77 23,6 12,58 53,1 80 10
18 400/3N/50 5,66 17,8 13,66 52,8 9,41 23,3 13,22 52,8 80 10
20 400/3N/50 7,65 22,3 16,65 35,3 11,4 27,8 16,65 35,3 80 6
26 400/3N/50 8,35 24,3 17,35 37,3 12,1 29,8 17,35 37,3 80 6
29 400/3N/50 10,55 29,3 19,55 42,3 14,3 34,8 19,55 42,3 80 10
39 400/3N/50 18,3 50,4 33,3 72,4 22,05 55,9 33,3 72,4 80 16
30 400/3N/50 16,04 48,2 31,04 70,2 19,79 53,7 31,04 70,2 80 16
40 400/3N/50 18,5 53,4 33,5 75,4 22,25 58,9 33,5 75,4 80 16
50 400/3N/50 22,3 63,4 37,3 85,4 26,05 68,9 37,3 85,4 100 25
55 400/3N/50 20,8 60 38,8 86 26,8 68,7 38,8 86 100 25
60 400/3N/50 22,8 64 40,8 90 28,8 72,7 40,8 90 100 25

70 400/3N/50 27,1 74 45,1 100 33,1 82,7 45,1 100 100 25
B = cooling only
R = cooling only + heaters

H = cooling only plus humidifier / dehumidification
T = complete version (cooling only + heaters + humidifier/dehumid.)

Centrifugal fans Radial fans

Mod V/ph/Hz n° kW OA FLA LRA n° Volt kW OA FLA LRA

07 - 10 230/1/50 2 4 17,5 -
15 - 18 230/1/50 2 8 35 -

20 - 26 - 29 400/3N/50 3 9 13 -

39 - 30 - 40 - 50 400/3N/50 5 15 22 -

55 - 60 - 70 400/3N/50 6 18 26 -

Electric heaters

Modelli V/ph/Hz n° kW OA FLA

ELECTRICAL SPECIFICATIONS

AIU

07 230/1/50 1 0,5 - 2,85 - 1 230/1/50 0,44 - 2,6 -
10 230/1/50 1 0,5 - 2,85 - 1 230/1/50 0,44 - 2,6 -
15 230/1/50 2 0,5 - 2,85 - 2 230/1/50 0,44 - 2,6 -
18 230/1/50 2 0,5 - 2,85 - 2 230/1/50 0,44 - 2,6 -
20 400/3N/50 1 2,4 - 7,3 - 1 400/3N/50 2,2 - 4,9 -
26 400/3N/50 1 2,4 - 7,3 - 1 400/3N/50 2,2 - 4,9 -
29 400/3N/50 1 2,4 - 7,3 - 1 400/3N/50 2,2 - 4,9 -
39 400/3N/50 1 4 - 11,7 - 2 400/3N/50 1,9 - 4,9 -
30 400/3N/50 1 4 - 11,7 - 2 400/3N/50 1,9 - 4,9 -
40 400/3N/50 1 4 - 11,7 - 2 400/3N/50 1,9 - 4,9 -
50 400/3N/50 1 4 - 11,7 - 2 400/3N/50 1,9 - 4,9 -
55 400/3N/50 1 6,5 - 20 - 3 400/3N/50 1,9 - 4,9 -
60 400/3N/50 1 6,5 - 20 - 3 400/3N/50 1,9 - 4,9 -
70 400/3N/50 1 6,5 - 20 - 3 400/3N/50 1,9 - 4,9 -

15

English 01/07

ACCURATE AX* - AW*

MAINTENANCE

AIU

07 - 10 230/1/50 1 3 2,25 9,8 -
15 - 18 400/3N/50 1 5 3,75 5,5 -

20 - 26 - 29 400/3N/50 1 5 3,75 5,5 -

39 - 30 - 40 - 50 400/3N/50 1 5 3,75 5,5 -

55 - 60 - 70 400/3N/50 1 8 6 8,7 -

Modulating humidifier

models V/ph/Hz n° kg/h kW OA FLA

07 400/3N/50 1 1,84 3,5 5,1 32
10 400/3N/50 1 2,72 5 7 46
15 400/3N/50 1 4,02 7,8 12,4 65,5
18 400/3N/50 1 4,66 8,3 12,1 74
20 400/3N/50 1 5,25 10 15 101
26 400/3N/50 1 5,95 12,2 17 123
29 400/3N/50 1 8,15 15,3 22 127
39 400/3N/50 1 10,3 17,8 27 167
30 400/3N/50 2 4,02 7,8 12,4 65,5
40 400/3N/50 2 5,25 10 15 101
50 400/3N/50 2 7,15 14,5 20 123
55 400/3N/50 2 7,15 14,5 20 123
60 400/3N/50 2 8,15 15,3 22 127
70 400/3N/50 2 10,3 17,8 27 167

Compressors

models V/ph/Hz n° kW OA FLA LRA

This section, aimed above all for the end user, is extremely impor­tant for the correct operation of the appliance.
Just a few operations completed scrupulously and regularly will
avoid serious damage to the components and expensive repairs
by specialist personnel.
The maintenance instructions are simple and do not require spe­cific technical knowledge of air-conditioning.
The purpose of this chapter is to assist and guide the user and
avoid having to unnecessarily call out specialist personnel.

The maintenance operations can be summarised as follows:

- Clean the air filter.

- Check and clean the condenser coils

- Check the water-cooled condensers for fouling.

- Check and clean the drains.

- Check the drive belts.

- Check the humidification system.

- General examination of the overall operation of the appliance.

- Visual check of the condition of the pressurised containers.

Cleaning the air filter

Authorised personnel: maintenance mechanic
Checks:
The gradual fouling of the filters reduces the flow-rate of the
conditioned air, with a consequent reduction in cooling capacity.
In the direct expansion units, a reduction in the air flow-rate may
cause the activation of the low pressure switch and/or cause seri­ous damage to the compressor.
This can be avoided by the periodical cleaning of the filters.
The frequency at which the filters must be checked exclusively

depends on the amount of dust in the environment.
In any case, the following are recommended:

- Every week check that the filters are clean

- Every two weeks clean the filters with a vacuum cleaner

- Every month wash the filters with soapy water

- Every 6 months replace the filters.
It is clear that the recommended times are purely indicative, and
in some cases it may be necessary to increase the frequency of
the checks and maintenance operations.
These operations must be carried out with the unit off and after
having made sure that the appliance is disconnected from the
power supply.

values for individual compressor

16

English 01/07

ACCURATE AX* - AW*

Checking and cleaning the condenser coils

Authorised personnel: maintenance mechanic
Checks:
In the hotter period, when the unit operates at maximum capaci­ty, the condensing coils must be able to offer the maximum heat
exchange.
Normally installed outside or communicating with the outside,
these may pick up dirt such as paper, dry leaves and dust, thus
reducing the heat exchange.
Make sure that this situation does not arise.
Failure to perform maintenance will cause the activation of the
high pressure switch and the unit to shutdown.
Frequently check the condition of the heat exchanger during the
poplar pollination period or the autumn (falling leaves).
Remove any objects accumulated on the coil and wash with a jet
of water.
These operations must be carried out with the unit off and after
having made sure that the appliance is disconnected from the
power supply.

Checking the water-cooled condensers for fouling

Authorised personnel: maintenance mechanic
Checks:
To check the water-cooled condensers for fouling, simply check
the water inlet and outlet temperature and compare it against
the condensing temperature.
Normally, for good heat exchange, the difference between the
water outlet temperature and the condensing temperature must
be 5.8°C.
Increases in these values, over time, indicate a reduction in effi­ciency and consequently the fouling of the condenser.
The condenser is cleaned by chemical washing and must be per­formed by specialist personnel.
This operation must be carried out with the unit off and after
having made sure that the appliance is disconnected from the
power supply).

Checking and cleaning the drains

Authorised personnel: maintenance mechanic
Checks:
All the water drains (humidifier and condensate) must ensure
perfect drainage, to avoid flooding in the room.
When the humidifiers drain the water, they discharge a quantity
of lime scale that depends on the hardness of the supply water.
This lime scale may accumulate in the bottom of the drain hose
and block the flow of water.
If cleaning is required, add ordinary descaler to the section of cir­cuit involved.
This operation must be carried out with the unit off and after
having made sure that the appliance is disconnected from the
power supply.

Checking the drive belt

Authorised personnel: maintenance mechanic
Checks:
On the units with fans coupled to the electric motor by pulleys
and drive belts, after a certain number of operating hours the belt
may become loose, sliding on the pulleys and causing excessive
wear.
This situation, if it persists, causes overheating and consequently
the breakage of the belt.
Loosening can be resolved using the special belt tightener fitted

on the appliance (this operation must be carried out with the
unit off and after having made sure that the appliance is discon­nected from the power supply).
Check the tension of the drive belts once a month.
Avoid excessively tightening the belts, as this may cause damage
to the bearings.

General examination of operation

Authorised personnel: system supervisor
Checks:
This is a general examination aimed at comparing the operation
of the appliance with the last check performed.
Consequently, any differences in the operating characteristics
over time can be highlighted.
A detailed and periodical visual check of the appliance and gener­al cleaning are always important to ensure correct operation.
The above-mentioned operations can in general be performed
once a month.
Naturally, in special situations and specific installations the fre­quency may change.
A well maintained system is unlikely to cause disruptions and
stoppages to the production cycles.

Visual check of the condition of the pressurised contain­ers

Authorised personnel: system supervisor
Checks:
Check the condition of the pressurised containers at least once a
year (if these are fitted).
It is very important to check that rust does not form on the sur­face, that there is no corrosion and that there are no visible
deformations.
If not controlled and stopped, surface oxidation and corrosion
will over time cause a decrease in the thickness of the container
and a consequent reduction in its mechanical strength.
Protect with paint and/or corrosion proofing products.
In the event of visible deformations, stop the unit and contact the
nearest service centre.

17

English 01/07

ACCURATE AX* - AW*

TIGHTENING THE DRIVE BELTS

AIU

ELECTRIC HEATERS

AIU

In the versions from frame 3 upwards, the fans in the standard
version are centrifugal with forward blades and belt drive.
A required periodical maintenance operation (at least once a
year) involves having specialist personnel check the correct ten­sion of the belt.
To check the tension, proceed as follows: apply a perpendicular
force of around 20 N (2 kg) to the centre of the belt (between
the 2 pulleys).
The belt must have a deformation of around 6-8 mm.
If this is not the case, adjust the tension using the worm screw
located on the slide that supports the electric motor.
Overly tight belts will cause unbalanced transmission.
Too loose belts, on the other hand, will cause the motor to over­heat and excessive power consumption.

DRIVE PULLEYS

Below is a description of how to assemble and dismantle the pul­leys if these require replacement or repair.

Dismantling
Take out the 2 safety screws and remove the pulley from the
elastic ring
See Fig.A

Assembly
Slide the elastic ring onto the motor pin. Insert the pulley on top,
then tighten the fastening screws
See Fig. B

ELECTRIC HEATERS

The overall power of the electric heaters is divided into a num­ber of elements, each with a power of 2/3/4 kW.
The colour of the wires on each element has the following mean­ing:

• BLACK wire = low power element (0.7/1/1.3 kW);

• WHITE wire = high power element (1.3/2/2.7 kW);

• RED wire = common.
The wires for each element are connected to contactors M5 and
KM6 on the electrical panel so as to balance the load between
the phases and create three stages of power (see the wiring dia­grams on the unit).

If having to replace the electric heaters, disconnect power to the
air-conditioner and wait until the heating elements have cooled
down.
After having replaced the heaters, make sure the earth is con­nected.

6-8mm

20N

A

B

18

English 01/07

ACCURATE AX* - AW*

HUMIDIFIER

AIU

SYSTEM COMPONENTS

Upon request, the air-conditioning unit can be fitted with an
immersed electrode humidifier (versions D and H).

1 Humidifier interface board:A3; (inside the electrical panel).
2 Current transformer TA1 (inside the electrical panel) for

measuring the current input of the steam cylinder.
3 Water fill tank.
4 High water level electrodes in the steam cylinder.
5 Overflow pipe (BEHIND THE CYLINDER).
6 Boiler cylinder (or steam cylinder).
7 Water fill solenoid valve:YV1.
8 Cylinder drain solenoid valve:YV2.
9 Microprocessor control board:A1.
10 Temperature and humidity probe: BH1.

3

4

6

7

8

9. B1

2. TA1

4

6.

8.YV2

7. YV1

5

3

1. A3

10. BH1

KM4

HUMIDIFIER OPERATING PRINCIPLE

In the immersed electrode humidifier, the current that runs
between the electrodes, through the water contained in the boil­er cylinder, generates the heat required to boil the water.
By controlling the level of the water and the concentration of
salts inside the steam cylinder (6) using the fill (7) and drain (8)
solenoid valves, the amount of current delivered can be regulated,
and measured using a current transformer (2).
When steam production is required, the humidifier contactor CU
closes (see the wiring diagram) so as to supply power to the
immersed electrodes.
When the current falls below the set value due to the lowering
of the water level, the fill valve (7) is opened.
The drain valve (8) is activated cyclically, depending on the char­acteristics of the supply water, so as to maintain the optimum salt
concentration inside the cylinder (6).
The only periodical maintenance operations required are the
inspection and cleaning of the parts in the steam production unit.
The operations indicated below should be performed annually,
preferably before shutting down the unit in summer.

STEAM CYLINDER

The steam cylinder requires periodical cleaning to remove the
scale deposits that form on the surface of the electrodes and the
flakes that deposit on the filter at the base of the cylinder.
To remove the cylinder,proceed as follows:

• completely drain the water from the boiler; to do this, see the
paragraph “MANUAL CONTROL” in the EVOLUZIONE con­troller instruction manual;

• disconnect the power supply by opening the main switch on
the electrical panel;

• remove, from the top of the cylinder, the hose that carries the
steam to the distributor;

• disconnect the power connections by unscrewing the knobs
on the cable ends and remove the plugs from the level elec­trodes;

• release the strap that secures the cylinder to the unit;

• slide the cylinder out upwards.

The steam cylinder can be reused a number of times after clean­ing the electrodes: if, however, the wear on the grills of electrodes
is such that these cannot be regenerated, they must be replaced.
The only spare part is the complete cylinder body (with filter
included).

19

English 01/07

ACCURATE AX* - AW*

TERMINAL AND BOARD CONFIGURATION

AIU

TROUBLESHOOTING

AIU

FILL AND DRAIN ASSEMBLIES

To ensure the correct operation of the humidifier, the supply/fill and
drain assemblies need to be inspected periodically.
Proceed as follows:

- completely drain the water from the boiler using the MANUAL
CONTROLS on the controller A1;

- disconnect the power supply by opening the main switch on the
electrical panel;

- remove the fill pipe from the 3/4 GAS fitting on the fill solenoid
valve;

- remove and clean the filter located inside the solenoid valve fit­ting;

- dismantle the drain assembly (shown in Figure 13), clean the pipes
and remove any flakes of scale from the cup-drain trap.

Check for voltage; close the main switch.The electrical panel is not powered

Check that the cutout IM in the auxiliary cir­cuits is armed.
Check the fuse on the main board.

The auxiliary circuits are not powered

Check for DC power.

The control panel does not start the
air-conditioner.

FAULT CAUSE SOLUTION

THE AIR-CONDITIO­NER DOESN'T START

See the controller manual.

The parameter settings on the microprocessor
controller are not correct.

See “LOW OR NO AIR FLOW”.The air flow-rate is too low or null.

Check the electrical connections and the
configuration of the controller.

The probe isn't working.

Check the thermal load in the room being
air-conditioned.

Thermal load higher than expected.

Check the electrical connections to the valve
servomotor. Open the valve using the manual
control knob.

Three-way valve not working.

Check for the flow of chilled water; check that
any on-off valves outside of the unit are open.

No flow of chilled water.

Check the operation of the water chiller.High temperature of the chilled water.

See “THE COMPRESSOR/COMPRESSORS
DON'T START”.

The compressor/compressors don't start,
despite being activated by the controller.

ROOM TEMPERATURE
TOO HIGH

Troubleshooting is simplified by the information provided by the
microprocessor controller: if an alarm is signalled, refer to the
control panel instruction manual.

If required, contact the nearest service centre, indicating the
probable causes of the fault.

20

English 01/07

ACCURATE AX* - AW*

See the controller manual.

The parameter settings on the
microprocessor controller are not correct.

Check that the heater thermal cutout is armed.
Check the power supply to the electric heaters.
If the heater safety thermostat is activated,
resolve the causes and reset the alarm.

The power of the heaters is not sufficient or
the heaters aren't working.

Check the flow-rate and the temperature of
the water hot.
Check the operation of the control valve
and the servomotor.

The hot water coil isn't working correctly.

Check the operation of the hot gas three-way
valve;
Check the operation of the compressor used
for post-heating: in this case, see “THE
COMPRESSOR/COMPRESSORS DON'T
START”.

The hot gas post-heating system isn't working
during the dehumidification plus post-heating
phase

Close the valve using the manual control knob
and replace the servomotor.

The three-way valve in the chilled water
circuit is stuck in the open position.

ROOM TEMPERATURE
TOO LOW

FAULT CAUSE SOLUTION

See the controller manual.

The parameter settings on the
microprocessor controller are not correct.

Check and calculate the latent load; check the
flow-rate and the conditions of the outside air;
check the inflow of outside air.

Latent load higher than expected

See “THE COMPRESSOR/COMPRESSORS
DON'T START”.

The compressor isn't working during the
dehumidification phase.

Check the operation of the solenoid valve that
controls the dehumidification circuit.

The dehumidification valve doesn't close.

See the controller manual; check the
operation of the panel and/or the probe.

The control system isn't working.

Lower the chilled water temperature until
there is condensation on the surface of the
coil

The chilled water is not cold enough to
dehumidify (energy saving and twin cool units)

AMBIENT HUMIDITY
TOO HIGH

21

English 01/07

ACCURATE AX* - AW*

Check the room temperature setting (see the
control panel manual).

The parameter settings on the microprocessor
controller are not correct.

Verificare la consistenza del carico latente.Latent load lower than expected.

Check the pressure of the supply water;
Check the operation of the manual control
system and the steam production unit (see the
control panel manual)

The humidifier isn't working.

See the control panel manual; check the
operation of the panel and/or the probe.

The control system isn't working.

AMBIENT HUMIDITY
TOO LOW

FAULT CAUSE SOLUTION

Check the power supply to the fans.The fans are not powered.

Clean the filter using a vacuum cleaner after
having shaken off the larger particles of dust.
Replace the filter if excessively clogged.
Check the correct calibration of the dirty filter
differential pressure switch F4.

The filters are blocked (possible activation of
the dirty filter alarm).

See the paragraph on AIR DISTRIBUTIONObstructions to the air flow.

Check the resistance of the fan windings; after
resetting, measure the voltage and power
input.

The fan thermal cutout has tripped.

EC radial fan speed set too low

Check the sizing of the air distribution system
(ducting, false-ceiling, underfloor plenum, grills)

Excessive pressure drop in the air distribution
system.

LOW OR NO AIR
FLOW

See “LOW OR NO AIR FLOW”.Insufficient air flow-rate

Check the continuity of the connection from
the safety thermostat to the control system.

Thermostat connection wire cut or broken

Replace the heater safety thermostat.Faulty thermostat

HEATER SAFETY
THERMOSTAT
ACTIVATED

22

English 01/07

ACCURATE AX* - AW*

Empty and recharge the circuit.

A) Air or incondensable gas in the refrigerant
circuit, seen by the presence of bubbles, despite
measuring a high subcooling.

Check the operation and the correct direction
of rotation of the fans on the outdoor heat
exchanger.
Check that the exchanger is not dirty and
remove any material that may be blocking it
(leaves, paper, seeds, dust, etc.) with a jet of
compressed air or with a brush;
Check the outdoor unit for any obstacles to
the flow of air and any recirculation of the coo­ling air;
Check that the temperature of the cooling air
does not exceed the design value.

B) Insufficient air flow-rate to the remote heat
exchanger or air too hot

Check the flow-rate, the pressure and the
temperature of the cooling water in the clo­sed circuit;
Check the calibration and the operation of the
pressure control valve.

Insufficient water flow-rate to the condenser
or water too hot.

Remove refrigerant from the circuit.

Excessive refrigerant charge; condenser
partially flooded. Excessive subcooling of the
liquid at the condenser outlet.

Check the opening of the valves.

Valves on the high pressure side of the circuit
partially closed.

HIGH COMPRESSOR
DISCHARGE
PRESSURE

FAULT CAUSE SOLUTION

Check the operation of the condenser fans
and the corresponding protection device;
repair or replace the faulty fans;
Check the calibration and the operation of the
remote condenser fan pressure switch or the
speed controller.
(See CONTROLLING THE CONDENSING
PRESSURE)

The condensing pressure control system
isn't working.

See “HIGH COMPRESSOR DISCHARGE
PRESSURE”.

The system is affected by an excessive
discharge pressure

HIGH PRESSURE
SWITCH ACTIVATED
(high compressor
discharge pressure)

Check the calibration and the operation of the
condenser fan pressure switch or the speed
controller;

The condensing pressure control system
isn't working (see the control panel manual).

Check the temperature of the cooling water;
Check the calibration and the operation of the
pressure control valve (if fitted);
Install a pressure control valve to manage the
flow-rate of water according to the conden­sing pressure.

Excessive water flow-rate to the condenser
or water too cold.

See “LOW COMPRESSOR SUCTION
PRESSURE”.

Suction pressure too low

LOW COMPRESSOR
DISCHARGE
PRESSURE

23

English 01/07

ACCURATE AX* - AW*

FAULT CAUSE SOLUTION

Check the ambient thermal load; check, above
all for intense dehumidification, the flow-rate
and the conditions of the outside air; check
the inflow of outside air.

Thermal load higher than expected

See “HIGH COMPRESSOR DISCHARGE
PRESSURE”.

The system is affected by an excessive
discharge pressure

Remove refrigerant from the circuitToo much refrigerant in the circuit.

Check that the thermostatic valve
superheating value is correct; check that the
valve sensor bulb is not discharged and that it
is correctly positioned, secured and
insulated”.a

Return of liquid refrigerant to the
compressor intake

HIGH COMPRESSOR
SUCTION PRESSURE

See “ROOM TEMPERATURE TOO LOW”.Room temperature too low

See “LOW OR NO AIR FLOW”.The air flow-rate is too low or null

Check the opening of the valve.

Liquid receiver outlet valve not
completely open

Check that the thermostatic valve
superheating value is correct; check that the
valve sensor bulb is not discharged and that it
is correctly positioned, secured and insulated”.

Refrigerant filter blocked

Check the liquid subcooling at the condenser
outlet; if necessary, restore the charge.

Insufficient refrigerant charge

LOW COMPRESSOR
SUCTION PRESSURE
(and possible defrosting
of the coil)

Check that the thermostatic valve superheating
value is correct (around 5°C).

Thermostatic valve not correctly calibrated
or faulty

Check and if necessary replace the dewatering
filter cartridge; the temperature difference
measured upstream and downstream of the
filter must be less than 2°C.

Dewatering filter cartridge dirty

See “LOW COMPRESSOR DISCHARGE
PRESSURE”.

The system is affected by an excessively
low discharge pressure

LOW PRESSURE
SWITCH ACTIVATED
(low compressor suction
pressure)

24

English 01/07

ACCURATE AX* - AW*

Dé Longhi Group - Via L. Seitz, 47 - 31100 Treviso (Italia)

COD.5787001000