AAON LN-140 - Manual (Page 33)

33
Lubrication
All original motors and bearings are
furnished with an original factory charge of
lubrication. Certain applications require
bearings be re-lubricated periodically. The
schedule will vary depending on operating
duty, temperature variations, or severe
atmospheric conditions.
Bearings should be re-lubricated at normal
operating temperatures, but not when
running.
Rotate the fan shaft by hand and add only
enough grease to purge the seals. DO NOT
OVERLUBRICATE.
Air-Cooled Condenser
The air-cooled condenser section rejects
heat by passing outdoor air over the fin tube
coils for cooling of the hot refrigerant gas
from the compressors. The heated air will
discharge from the top of the section
through the axial flow fans.
The condenser coils should be inspected
yearly to ensure unrestricted airflow. If the
installation has a large amount of airborne
dust or other material, the condenser coils
should be cleaned according to the
microchannel coil cleaning section.
Brazed Plate Heat Exchanger Cleaning
Because of a normally high degree of
turbulence in brazed plate heat exchangers,
for many applications the heat exchanger
channels are self-cleaning. For applications
that are not self-cleaning (i.e. hard water at
high temperatures, etc.) or applications
where additional cleaning is desired, it is
possible to clean the brazed plate heat
exchanger by circulating a cleaning liquid.
Use a tank with weak acid, 5% phosphoric
acid (H3PO4) or, if the exchanger is
frequently
cleaned, 5% oxalic acid
(H2C2O4). Pump the cleaning liquid
through the exchanger. For optimum
cleaning, the cleaning solution flow rate
should be a minimum of 1.5 times the
normal flow rate, preferably in a back-flush
mode. After cleaning, the heat exchanger
must be rinsed with clean water. A solution
of 1-2% sodium hydroxide (NaOH) or
sodium bicarbonate (NaHCO) before the last
rinse ensures that all acid is neutralized.
E-Coated Coil Cleaning
Documented routine cleaning of e-coated
coils is required to maintain coating
warranty coverage.
Surface loaded fibers or dirt should be
removed prior to water rinse to prevent
restriction of airflow. If unable to back wash
the side of the coil opposite of the coils
entering air side, then surface loaded fibers
or dirt should be removed with a vacuum
cleaner. If a vacuum cleaner is not available,
a soft non-metallic bristle brush may be
used. In either case, the tool should be
applied in the direction of the fins. Coil
surfaces can be easily damaged (fin edges
bent over) if the tool is applied across the
fins.
Use of a water stream, such as a garden
hose, against a surface loaded coil will drive
the fibers and dirt into the coil. This will
make cleaning efforts more difficult. Surface
loaded fibers must be completely removed
prior to using low velocity clean water rinse.
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING