AAON RN-140 - Manual (Page 88)

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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 for fin and tube and
microchannel coils.
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.
A
monthly clean water rinse is
recommended for coils that are applied in
coastal or industrial environments to help to
remove chlorides, dirt, and debris. It is very
important when rinsing, that water
temperature is less than 130°F and pressure
is than 900 psig to avoid damaging the fin
edges. An elevated water temperature (not to
exceed 130°F) will reduce surface tension,
increasing the ability to remove chlorides
and dirt.
Quarterly cleaning is essential to extend
the life of an e-coated coil and is required
to maintain coating warranty coverage.
Coil cleaning shall be part of the unit’s
regularly
scheduled maintenance
procedures. Failure to clean an e-coated coil
will void the warranty and may result in
reduced efficiency and durability.
For routine quarterly cleaning, first clean the
coil
with the below approved coil
cleaner. After cleaning the coils with the
approved cleaning agent, use the approved
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING
Harsh chemicals, household bleach,
or acid cleaners should not be used
to clean outdoor or indoor e-coated
coils. These cleaners can be very
difficult to rinse out of the coil and
can accelerate corrosion and attack
the e-coating. If there is dirt below the
surface
of the coil, use the
recommended coil cleaners.
High velocity water from a pressure
washer or compressed air should
only be used at a very low pressure
to prevent fin and/or coil damages.
The force of the water or air jet may
bend the fin edges and increase
airside pressure drop. Reduced unit
performance
or nuisance unit
shutdowns may occur.
CAUTION
CAUTION