Swegon CoolDX Series Installation And Maintenance Instructions Manual Download Page 4

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GB.COOLDX.IN.E.130821

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1.2 Basic function diagram

Operation

There are two refrigerant circuits in the cooling unit. The
circuits are separate from one another.
Each circuit is equipped with a finned condenser, a finned
evaporator and a compressor.
The two compressors have different capacity, which ena-
bles control in 3 steps.
The gaseous refrigerant is compressed by compressors M1
and M2 and from there moves on to condenser COND,
where it is chilled by the extract air and is condensed to
liquid form.
The pressure and the temperature decrease as the refri-
gerant in fluid form flows through expansion valves VET1

COND Condenser
VSH1 Overpressure protect. (not COOL DX Top)
VSH2 Overpressure protect. (not COOL DX Top)
B1-1

High pressure sensor

B2-1

Low pressure sensor

B1-2

High pressure sensor

B2-2

Low pressure sensor

BP1-2 Alarm pressure switch for high pressure
BP2-2 Alarm pressure switch for high pressure
M1

Compressor

Compressor (size 80 cap.var. 3 only)

VSL1

Underpressure prot. (not COOL DX Top)

VSL2

Underpressure prot. (not COOL DX Top)

EVAP

Evaporator

VET1

Expansion valve with thermostat

VET2

Expansion valve with thermostat

IPL1

Sight glass, refrigerant circuit 1

IPL2

Sight glass, refrigerant circuit 2

FD1

Filter drier

FD2

Filter drier

and VET2.
From the expansion valves the refrigerant moves on to
evaporator EVAP, where the refrigerant evaporates and
chills the outdoor air.
From evaporator EVAP, the evaporated refrigerant is con-
veyed further to the suction side of the compressors where
it is again compressed.

Control

The cooling capacity is regulated in three binary steps by
having one or two compressors in operation.

The cooling compressors are controlled from the GOLD
unit via relays on the IQnomic Plus module mounted in the
COOL DX/COOL DX Top.

Step 1:

When cooling is needed, Compressor M1 is start-

ed.

Step 2:

If more cooling is needed, Compressor M2 starts

and at the same time Compressor M1 stops. An adjust-
able time delay (a step duration of 300 seconds) ensures
that Compressor M2 will not start until Compressor M1 is
operating at full capacity.

Step 3:

If even more cooling is needed, Compressor M1 is

restarted and is run at the same time as Compressor M2.
This third cooling step is also delayed by a preset time de-
lay setting. In addition, the restarting time (300 seconds)
for Compressor M1 shall have expired.
If less cooling is needed and the compressors are subse-
quently switched out step-by-step, there will be no delay
between compressors. The restarting time (300 seconds)
for Compressor M1 shall have expired to enable it to start
again in Step 1 after it has been operated in Step 3.
If any compressor is stopped, the restarting time must
expire before a restart can take place. The restart time is
calculated from one start to the next start.
Low/high pressure sensors B1/B2 measure the pressure
conditions in the system and transmit readings to the
control system to ensure that these are within stipulated
limits.
If the pressure in the cooling circuit becomes too low, or
if the pressure in the condenser circuit becomes too high,
the compressor is stopped and the text PRESSURE LIMIT-
ING is displayed alternately in the hand-held micro termi-
nal of the GOLD air handling unit.
When the restart time has expired, the compressors will try
to restart.
If the pressure increases more, high pressure switches
BP1-2 and BP2-2 will trip and stop the GOLD unit and the
COOL DX cooling unit.
Alarms 164 and 165 will be displayed in the hand-held
micro terminal of the GOLD unit.
Pressure switches BP1-2 and BP2-2 can be manually reset
by pressing a button under each protective sock on the
upper side of the pressure switch. This can be done with-
out removing the protective sock.