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UNIT AIRFLOW GUIDELINES
Each Desert Aire Dehumidifier is designed to operate at a specified airflow rate. Airflow must be set prior to
starting the refrigeration circuit to assure that problems are not caused by improper unit airflow.
Using a manometer or Magnehelic® pressure differential gauge, determine the pressure drop in inches water
column (in WC) across the unit's condenser coil. Units are equipped with pressure tap holes on the side of the
unit just for this purpose. One is in the blower compartment just downstream of the condenser, one is in the
section between the evaporator and the condenser and one is in the filter rack. See the table in Figure 16 for
the proper pressure drop for your unit.
Increasing or decreasing blower speed can be accomplished by adjusting the variable pitch motor pulley.
To adjust the variable pitch pulley, first loosen set screw. To slow down the blower turn the outer pulley face
counter clockwise. To speed up the blower turn the outer pulley face clockwise.
Failure to meet proper pressure drop without high amping the blower motor is an indication of other problems.
If this happens, call (262) 946-7400 and ask for the service department. Please be
prepared with system serial and model number.
intervals. To speed up the blower, turn the outer pulley face clockwise
(to increase its pitch diameter) in half turn intervals.
After Every Adjustment Be Sure To:
•
Tighten the set screw against the flat spot on the pulley hub so you don't
damage any threads. This will insure that the set screw as well as the pulley
do not loosen during operation.
•
Adjust the belt tension as needed.
•
Check to assure that the blower motor current draw does not exceed the
rating printed on the rating plate.
NOTE: System airflow will tend to decrease over time due to belt wear as well as
dirty filters and ducts. Always adjust the blower speed to the high side of the
pressure drop range.
If the blower motor current draw exceeds its rating but your airflow is still too low, the
static pressure losses in the ductwork and grilles may be higher than the unit was
designed for. If this happens, consult Desert Aire's Service Department. Please be
prepared with your unit's model number and serial number.
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Desert Aire - LW Manual
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