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.
To help eliminate compressor cycling, a two stage thermostat is used in this unit, with a thermostat sensor
located in the return air stream of the enclosure. The first stage, which controls the compressor, has a set
point of 64°F (18°C).The second stage, which controls the condenser blower (fan), has a set point of 66°F
(19°C). The first stage has a temperature differential of 11°F (6°C), and the second stage has a temperature
differential of 0.5°F. When the return air temperature is above 70°F the air conditioner will run constantly.
When the return air temperature drops below 66°F the thermostat’s second stage will start to cycle the
condenser blower and the return air will fluctuate from 64°F to 70°F. In conditions of very low ambient
temperature and low internal load the return temperature could drop below 64°F. In this case the thermostat’s
first stage will start to cycle the compressor and the return air temperature will fluctuate from 63°F to 75°F.
In reality this situation would occur rarely, and then only for a short period of time. The advantage of a two
stage thermostat is that it avoids compressor cycling and controls the return air temperature to a very narrow
temperature range of 6°F; from 64°F to 70°F.
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.
VI. Pre-Installation Testing
Before mounting the air conditioner to the enclosure, test for proper operation. This will verify the shipping
integrity of the system. Please follow the steps below prior to installation.
CAUTION
