7
7. TURN POWER ON. (Close unit electrical disconnect.)
NOTE: Be sure power is off before making any adjust-
ments inside unit.
8. Check fan and motor operation. Motor to fan wheel rota-
tion must match airflow direction shown in Fig. 2 and 3.
Set unit air delivery for required blower rpm per job sub-
mittals or product data catalog. Adjust fan motor pulley
(Fig. 7) as follows:
a. Loosen setscrew on movable pulley flange.
b. Screw flange toward fixed flange to increase fan
speed and away from fixed flange to decrease speed.
c. Reset setscrew.
d. Check belt tension. The drive belt should be ten-
sioned to allow
1
/
2
to
3
/
4
-in. deflection at the mid-
point between pulleys with moderate pressure.
Inspect the unit for loose wires, correct blower wheel opera-
tion, and loose or missing access panels or doors. Unless other-
wise required for balancing and start-up procedures, units
should not be operated without proper ductwork; supply/return
air grilles, and access panels and/or doors in place.
START-UP
Start-up procedures vary depending upon the time of year
(summer or winter) and building characteristics (new building
or old building, occupied or unoccupied, etc.).
Start-up in the Cooling mode requires that proper care be giv-
en to avoid condensation problems. Condensation forms on sur-
faces that are colder than the dew point of the surrounding air. If a
unit is started and is fed low-temperature chilled water in a hot,
humid setting, condensation will form on many parts of the unit.
In order to avoid excessive condensation, water of higher
temperature should be used, approximately 65 to 70 F. Also, the
building should be as completely enclosed as possible and
outside-air supply fans and toilet and kitchen exhaust fans should
be off.
As the building temperature drops, the chilled water temper-
ature can gradually be reduced until it reaches 50 F. At this
point, the outside-air fans can be turned on. When the chilled
water temperature is reduced to its design point, the exhaust
fans can be turned on.
Air System Balancing —
All ductwork, air grilles, fil-
ters, and access doors and panels must be complete and con-
nected to establish actual system operating conditions before
air system balancing procedures are started.
NOTE: Units are factory set for system designed operating
conditions specified at the time of order entry.
Proper belt drive alignment and tension must be maintained
when adjusting the unit fan drive speed. The drive belt tension
should not exceed
3
/
16
-in. deflection midway between the pul-
leys under 8-lb. of force. New belts tend to stretch during their
initial period of use. After 5 days of operation, check and read-
just belt tension and pulley alignment if necessary. Failure to do
so may result in excessive unit noise and/or premature belt/
bearing failure.
SERVICE
Clean Coils
1. Brush between coil fins with a stiff wire brush. Do not
bend fins. Follow up by cleaning with a vacuum cleaner.
If coil is cleaned with an air hose, take care not to drive
dirt and dust into other components.
2. Install clean air filters.
Check Drain —
Check drain pan, drain line and trap at
start of each cooling season. A standard type pipe cleaner for
3
/
4
-in. ID pipe can ensure removal of obstructions so that con-
densate is carried away. Check the drain line at filter cleaning
time during the cooling season.
Fan and Motor Bearings —
Fan shaft bearings are
permanently lubricated and sealed, and need no attention.
Check tag on motor for motor bearing lubrication instructions
(if any). Most motors furnished with these units are perma-
nently lubricated.
Align Pulley —
Loosen pulley setscrew(s). Align pulleys
by using a straight edge as shown in Fig. 7. Retighten set-
screw(s).
Adjust Fan Belt Tension —
Loosen fan motor base
mounting screws. Reposition the motor so that belt deflection
does not exceed
3
/
16
-in. at belt midpoint under 8-lb of force.
Retighten motor mounting screws and recheck fan belt tension.
Clean Fan Wheel —
Use a stiff brush or vacuum to re-
move dirt and debris from scroll. Wipe all fan surfaces with a
damp cloth.
Clean or Replace Air Filters —
At the start of each
cooling season and after each month of operation (more or less
depending on operating conditions), replace unit filter.
CAUTION
Do not exceed motor nameplate FLA (full load amps).
Operator must confirm motor current draw before putting
unit into service and again after air balancing the system.
Failure to do so could result in equipment damage.
CAUTION
Follow all safety considerations previously outlined. Fail-
ure to do so could result in personal injury or equipment
damage.
Fig. 7 — Fan Pulley Adjustments
a42-89tf
WARNING
Lock open and tag electrical disconnect before servicing
equipment. Failure to do so could result in personal injury
or death.
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