23
EVAP. CONDENSER SECTION - cont.
STAINLESS STEEL SUMP
PRIOR TO UNIT INSTALLATION
Propeller Fans and Motors
The fans are directly mounted on the motor shafts and
require minimal maintenance except to assure they are
clear of dirt or debris that would impede the airflow.
Recommended Annual Inspection:
In addition to the above maintenance activities, a
general inspection of the unit surface should be com-
pleted at least once a year. Surface corrosion in spot
areas should be wire brushed and cleaned thoroughly.
These locations may then be resurfaced with rust
inhibitive paint. Remove spray header and flush out.
Cycles of concentration (the ratio of dissolved solids in
recirculated water to dissolved solids in make-up), should
be determined and monitored frequently by a competent
water treatment expert.
To limit cycles of concentration to maintain the above
guideline, it is necessary to “bleed” a certain portion of
the recirculated water. This is achieved automatically
with a solenoid valve actuated by a conductivity meter
set at the desired conductivity corresponding to the
desired cycles of concentration. It should be noted that
these are guidelines and even though these individual
values are met, under certain conditions the water qual-
ity can be aggressive. For example, water with very low
alkalinity and levels of chlorides and sulfates approach-
ing maximum recommended levels can be corrosive.
Bleed: All AAON evaporative condensers are furnished
with a bleed system fitting and valve to continuously
remove a small portion of the recirculated water to keep
the water quality within the above listed parameters.
This device is located on the discharge side of the pump.
It is important to note since “bleed” rate is a function of
evaporation rate (i.e., amount of heat rejected), if the
bleed setting is manual based on design heat load, too
much water will be removed when the heat load is less
than design.
The AAON evaporative condenser is equipped with a
desuperheater. The desuperheater coil is located above
the eliminators. Approximately 22% of the total heat of
rejection is accomplished with the desuperheater. Water
usage of the AAON evaporative condenser is approxi-
mately 22% less than evaporative condensers not equipped
with a desuperheater.
Hardness as CaCO3
PH
Alkalinity as CaCO3
Total Dissolved Solids
Chlorides As NaC1
Sulfates 750 PPM Max
6.5 to 9.0
500 PPM Max
500 PPM Max
2000 PPM Max
1500 PPM Max
Recirculating Water Quality Guidelines
Recommended Monthly Inspection
1. Clean sump section interior. Dirt and other impuri-
ties which have accumulated in the sump should be
removed from the sump area. Shut off water to float
valve and open the drain connection for flushing of
the sump.
2. Clean sump suction strainer.
3. Check water operating level. Adjust float as required.
4. Inspect fan motor(s) and water circulation pump(s)
and lubricate per the lubrication nameplate or
manufacture’s recommendations.
5. Inspect axial fans and eliminators removing any
debris which may have accumulated during operation.
6. Inspect the water distribution system to insure that
nozzles and spray orifices are functioning correctly.
The inspection should be made with the circulation
pump on and fans off.
Mist Eliminators
The mist eliminators must be correctly positioned when
they are replaced during cleaning or service.
Air Inlet
Inspect the air inlet louvers and mist eliminators on a
monthly basis to remove any paper, leaves or other debris
that may block the airflow.
Stainless Steel Base Pan
The base pan under the tube bundles is stainless steel
and may sometimes become tarnished due to contamina-
tion. These surfaces should be inspected yearly to ensure
they remain clean of any contamination that may result
in damage. Any surfaces that show contamination
should be cleaned ONLY with a commercial stainless
steel cleaner to restore the initial appearance.
WATER QUALITY
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