5
V. Principles of Operation
Kooltronic Air Conditioners are required when the
equipment operating temperature must be kept
near or lower than the ambient room temperature,
and/or the cabinet must be sealed from dust,
fumes, oil, corrosives and other contaminants.
These Air Conditioners utilize a "Closed-Loop
Cooling System" to ensure optimum performance
of the installed components.
Closed-Loop cooling seals the electronic enclosure
from hostile elements in the environment. Two
separate circulation systems are employed. The
internal system cools and dehumidifies the air
inside the cabinet, totally isolating the sensitive
electronics and other components from the
environment. The external system uses circulating
ambient air or water to discharge the heat removed
from the electronics. The heat is dissipated from the
enclosure by means of the vapor compression
refrigeration cycle. This takes place in a
hermetically-sealed refrigeration system, utilizing
either an air-cooled or water-cooled condenser
heat exchanger. The warm air inside the enclosure
is drawn through the evaporator coil where it is cooled, dehumidified and returned.
Any enclosure moisture accumulated on the evaporator coil is collected in the condensate tray and removed
through the drain tube to the condensate evaporator. Condensate evaporates in the condensate evaporator and is
released to the ambient air by the condenser impeller.
The heat removed through the evaporator coil is transferred by the compressed refrigerant to the condenser coil.
Ambient air is then passed through the condenser coil, where it absorbs the heat and is then discharged to the
environment.
This unit is equipped with a Low Temperature Thermostat to prevent the evaporator coil from freezing. In conditions
of low ambient temperature and low enclosure load, the thermostat regulates the return air temperature from
75°F to 86°F. The standard set point of the Low Temperature Thermostat is 75°F. The set point can be
changed to 70°F or to 79°F by changing the location of the thermostat jumper (see illustrations below).
The Low Temperature Thermostat has a test start relay. When the air conditioner is turned on it will run constantly
for the first 15 minutes regardless of external temperatures. Afterwards, if the entering evaporator air temperature
is lower than the thermostat set point, the compressor and condenser blower will stop, and the thermostat will begin
to control the air conditioner.
The crankcase compressor heater allows the unit to start with an ambient temperature of 0
o
F. In applications having
frequent voluntary heat load fluctuations, an optional Compressor Short Cycle Protector is recommended.
CONDENSER
AIR OUT
SUPPLY
AIR OUT
RETURN
AIR IN
CONDENSER
AIR IN
RT TOP MOUNT
2.06
[52.3]
.17
[4.3]
2.60
[66.0]
2
1
1
2
4
3
J2
3
4
5
10
9
8
7
6
1
2
3
J1
CG
RELAY
CONTACTS
N.O.
240 VAC
120 VAC
TEMPERATURE
SENSOR
Mounting Holes (4)
.156 [3.9] DIA.
ADJUSTING
PINS
3
2
1
4
70ºF - Connect 1 and 2
75ºF - Connect 1 and 3
79ºF - Connect 1 and 4
Thermostat Jumper
ELECTRONIC
THERMOSTAT
CONTROL
Electronic Thermostat Control
Dimensions, inches [mm], are for reference only
and are subject to change.
