AAON RZ Series, Installation Operation & Maintenance

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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 (H
3
PO
4
) or, if the exchanger is
frequently cleaned, 5% oxalic acid (H
2
C
2
O
4
).
Pump the cleaning liquid through the
exchanger. For optimum cleaning, the
cleaning solution flow rate must 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.
Air-Cooled Condenser
The air-cooled condenser section rejects heat
by passing outdoor air over the microchannel
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.
Inspect the condenser coils annually to
ensure unrestricted airflow. If the installation
has a large amount of airborne dust or other
material, clean the condenser coils with a
water spray in a direction opposite to airflow.
Care must be taken to prevent damage to the
coils.
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. See the AAON
E-Coated Coil Maintenance Record sheet.
Surface loaded fibers or dirt must 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 must 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 must 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 less than 100 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.
Electric shock hazard. Shut off all
electrical power to the unit to avoid
shock hazard or injury from rotating
parts.
WARNING