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 blower.
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 on page 8).
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 heater kit consists of a heater, a heat control thermostat and a heater limiter. The heater control
thermostat is a bimetal disk with a fixed set point of 60°F. When the entering evaporator air temperature rises
above 60°F the heater shuts off, and when the evaporator air temperature falls below 40°F the heater will
engage. The contact points of the alarm thermostat are normally closed. If the entering evaporator air
temperature exceeds 130°F the alarm thermostat contacts open, and when the temperature drops below
130°F the contacts close.
A condenser blower switch is standard on this unit. When the ambient temperature is above 95°F the
condenser fan will run at full speed. When the ambient temperature is lower than 95°F the condenser fan will
cycle. In applications having frequent voluntary heat load fluctuations, an optional Compressor Short Cycle
Protector is recommended.
When the Kooltronic Air Conditioner is properly sized it should operate constantly and maintain 75°F to
115°F enclosure temperature, depending on the ambient temperatures.
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K2A6C12HTL
