McQuay RAH 047C, Руководство по установке и обслуживанию

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McQuay IM 987 93
Unit Options
Bearings
Bearings are the most critical moving part of the fan and
should be inspected at periodic intervals. Locking collars and
set screws, in addition to fasteners attaching the bearings to the
bearing plate, must be checked for tightness. In a clean
environment and temperatures above 32°F/below 200°F, fan
shaft bearings with grease fittings should be lubricated
semiannually using a high quality lithium based grease. If
unusual environmental conditions exist temperatures below
32°F/above 200°F, moisture or contaminants, more frequent
lubrication is required.
With the unit running, add grease very slowly with a manual
grease gun until a slight bead of grease forms at the seal. Be
careful not to unseat the seal by over lubricating or using
excessive pressure. Bearings without grease fittings are
lubricated for life.
Fasteners and Setscrews
Any fan vibration has a tendency to loosen mechanical
fasteners. A periodic inspection should include checking all
fasteners and set screws for tightness. Particular attention
should be paid to setscrews attaching the propeller to the shaft
and the shaft to the bearings. Loose bearing set screws will
lead to premature failure of the fan shaft.
Lubrication
Refer to “Bearings” above for bearing lubrication. Many
fractional horsepower motors installed on the smaller fans are
lubricated for life and require no further attention. Motors
equipped with oil holes should be oiled in accordance with the
manufacturer’s instructions printed on the motor. Use a high
grade SAE 20 machine oil and use caution not to over
lubricate.
Motors supplied with grease fittings should be greased
according to directions printed on the motor.
Removal of Dust/Dirt
Thoroughly clean the exterior surface of the motor, fan panel,
and entire propeller periodically. Dirt can clog cooling
openings on motor housings, contaminate bearing lubricant,
and collect on propeller blades causing severe imbalance if left
unchecked. Use caution and do not allow water or solvents to
enter the motor or bearings. Under no circumstances should
motors or bearings be sprayed with steam or water.
Exhaust Fan On/Off Control
The exhaust fans are turned on and off based on building static
pressure, outdoor air damper position, and discharge fan
capacity. Exhaust fans do not have to always run while the
supply fan is on, as does a return fan. They are turned on and
off through output MCB-B02 on the Main Control Board. For
detailed information on Propeller Exhaust Fan Control, refer to
the operation manual supplied with the unit (OM 138 or
OM 137).
Exhaust Fan Troubleshooting
Table 15 provides guidelines for troubleshooting problems
with the propeller exhaust fan options. A list of parts is
provided in
Figure 108, page 92 .
Table 15: Propeller Exhaust Fan Troubleshooting
Problem Cause Corrective Action
Reduced
Airflow
System resistance is too
high. Check backdraft dampers for proper operation. Remove obstructions in ductwork. Clean dirty filters.
Check for adequate supply for air exhaust fans or exhaust air for supply fans.
Unit running backwards. See “Prestarting Checks” on page 101
Fan speed too low. Increase fan speed
Excessive dirt on propeller. Clean propeller
Excessive
Noise
Bearings Tighten bearing collars and setscrews. Lubricate bearings. Replace defective bearings.
V-Belt drive Tighten pulleys on motor shaft and fan shaft. Adjust belt tension. Align pulleys. Replace worn belts or pulleys.
Excessive vibration Clean dirt build-up from propeller. Check all setscrews and fasteners for tightness. Check for worn bearing.
Correct propeller imbalance. Check for loose dampers, guards or ductwork.
Defective motor Replace motor.