© 2013 Pentair Equipment Protection
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PRINCIPLES OF OPERATION
Hoffman cooling air conditioners are designed specifically to cool and dehumidify the internal environments
of cabinets and enclosures which are used to package electronic components, thus assuring a cool, clean
atmosphere for reasons of optimum performance and longevity.
Hot air inside the electronic cabinet or enclosure is drawn into the air conditioner by means of the evaporator
duplex blower. This air is drawn through the evaporator coil, cooled and discharged back through the cold air
outlet into the cabinet or enclosure. Excessive moisture in the air condenses on the evaporator coil and ultimately
collects in the condensate tray where it is then discharged to the outside of the air conditioner by the condensate
drain tube which projects out of the unit.
The moisture that the enclosure air can contain is limited. If moisture flows from the drain tube continuously, this
can only mean that ambient air is entering the enclosure. Remember that frequent opening of the enclosure’s
door admits humid air which the air conditioner must then dehumidify.
The “closed loop” design of the air conditioner assures that the clean cooled air never mixes with the hot, dirty
ambient air. Generally, the cabinets or enclosure air which is being cooled and recirculated over and over again
does not require any filtering media.
Water is used to provide cooling for the hot condensing refrigerant. Also see WATER USAGE, page 8.
If electrical power to the air conditioner is momentarily interrupted and immediately reapplied (within 3 to 5
seconds), the compressor may not restart due to the high back pressure of the compressor.
NOTE:
Do not attempt to restart the air conditioner for at least one (1) minute after the unit has been
accidentally or intentionally shut off.
It takes a minimum of one (1) minute after shut-down for the compressor suction and discharge pressures to
equalize in order to restart the air conditioner.
NOTE:
Operating the air conditioner at ambient temperatures below minimum or above maximum
temperatures indicated on the nameplate will void all warranties.
It is recommended that the warranty section of this manual be read in order to familiarize
yourself with parameters of restricted operation.
It is very important to make sure that the plastic plug installed in the outlet of the condensate drain tube be
removed prior to operation of the air conditioner. Not removing this plug will cause the collected condensate or
water to back up into the drain tube and flood the condensate tray. This flooding or overflowing water could then
be transmitted into the electronic cabinet or enclosure by the air exhausted from the evaporator blower, thus
causing damage to expensive electronic components - see Figure 4.
The moisture that the enclosure air can contain is limited. If moisture flows from the drain tube continuously, this
can only mean that ambient air is entering the enclosure. Remember that frequent opening of the enclosure’s
door admits humid air which the air conditioner must then dehumidify.
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