Exhaust Fan On/Off Control; Ultraviolet Lights Option - Daikin RDT-135c Installation And Maintenance Manual

Unit Options: Exhaust Fan On/Off Control
Bearings
Bearings are the most critical moving part of the fan; inspect
them at periodic intervals. Check locking collars, set screws,
and fasteners that attach bearings to the bearing plate for
tightness. In a clean environment and temperatures above
32°F/below 200° F, lubricate fan shaft bearings with grease
fittings 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. Pay particular attention
to setscrews attaching the propeller to the shaft and the shaft to
the bearings. Loose bearing set screws lead to premature
failure of the fan shaft.
Lubrication
Refer to "Bearings" for bearing lubrication. Many fractional
horsepower motors installed on the smaller fans are lubricated
for life and require no further attention. Oil motors equipped
with oil holes 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. Grease
motors supplied with grease fittings according to directions
printed on the motor.
Removing 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, see the
operation manual supplied with the unit (OM 138 or OM 137).
Exhaust Fan Troubleshooting
Table 24 provides guidelines for troubleshooting problems
with the propeller exhaust fan options. A list of parts is
provided in Table 103.
98

Ultraviolet Lights Option

When this option is employed, ultraviolet C light bathes the
moist surfaces on the coil and drain pan, killing most
microorganisms that can grow there.
Typically, ultraviolet lights are installed on the leaving side of
the cooling coils in the unit. Each light module is mounted on a
rail and is removable for convenient bulb replacement.
UV Light Power Disconnect switches (two per door) are
factory installed on every door that allows a direct line of sight
to the UV lamps when opened. These switches are designed to
prevent UV exposure when cabinet doors are opened and must
not be disabled.
A viewing window near the UV lights allows viewing to
determine if the lights are energized. The viewing windows
use specially designed glass that blocks harmful UV light.
UVC exposure is harmful to the skin and eyes. Looking at an
illuminated bulb can cause permanent blindness. Skin
exposure to UVC can cause cancer.
Always disconnect power to unit before servicing. Do not
operate if disconnect switch has been disabled.
Figure 104. Typical ultraviolet light installation
Cooling
Coil
View
Window
WARNING
Light Power
Disconnect
Switch
Ultraviolet
Light
Units
AIRFLOW
Light Power
Disconnect
Switch
IM 738-2