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4.2 Air-Cooled Refrigerant Condensers - Special
Instructions
A. The coil of the condensing section must be kept clean
to maintain refrigeration capacity. Monthly, or as
required, blow out condenser coil with compressed air.
If heavily contaminated, coils can be cleaned with mild
detergent and water. In exceptionally dirty locations a
furnace type filter can be installed in front of the
condenser intake to prevent rapid fouling of coil. If a
filter is used it must be changed regularly to prevent a
restriction of the cooling air flow.
B. Operational Deficiencies
1. Condenser Cooling System - High head pressure can
be caused by insufficient cooling air flow across the
condenser, too high an ambient air temperature or a
dirty condenser. Check to determine if condenser
fan(s) are running (see fan control note below) and
that no obstructions are too near the face of the
condenser. Ambient air temperature should be
checked at local heat sources or recirculating air might
raise the actual air temperature above the average
room temperature. The condenser should be checked
and cleaned, if dirty.
2. Fan Control - In order to assure satisfactory operation
of the air-cooled unit at low ambient temperatures, a
fan control switch has been provided to automatically
stop and start fan(s). This switch is actuated by the
unit head pressure and operates fan(s) individually to
maintain a minimum head pressure.
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4.3 Water-Cooled Refrigerant Condenser - Special
Instructions (Cleanable shell and tube type)
A. Water tubes should normally be mechanically cleaned
periodically to assure optimum condenser efficiency.
How often should they need cleaning depends on so
many variables that it is impossible to recommend a
schedule. Some will never need cleaning, others
perhaps need cleaning once a year. In rare cases,
cleaning is required several times a year.
Frequency of cleaning will depend on individual water
conditions, so a suitable cleaning schedule should be
worked out based on experience. An inspection of the
water tubes is recommended after the first six (6)
months of operation to aid in establishing a cleaning
schedule.
Proper operation of cooling towers will increase the
interval between cleaning considerably. The tower
overflow (bleed-off) rate should be checked fre-
quently. Most cooling tower manufacturers recom-
mend an overflow of about ten percent (10%) of the
water circulated. If a tower is operated with insuffi-
cient overflow, the resulting mineral concentration in
the water can cause rapid and heavy fouling inside the
condenser tubes. This will necessitate excessively
frequent cleaning and may lead to severe corrosion.
See CLEANING INSTRUCTIONS (Section 4.2.C) for de-
tailed cleaning instructions, methods and procedures.
B. Operational Deficiencies
1. High head pressures- particularly high (head) pressure
indicates (but does not always mean) a fouled con-
denser. It is advisable to double check the refrigeration
system to make sure that fouling is actually causing
the trouble.
The following possibilities should always be checked
before cleaning is undertaken.
a. Refrigerant overcharge: Feel side of condenser for
high liquid level
b. Clogged water strainer: Check and clean if neces-
sary.
c. Air in Refrigeration System: Check system pressure
after unit has been "OFF" for one (1) hour. Com-
pare this pressure with the refrigeration pressure
at ambient temperature. They should be the same.
If system pressure is high, purge air from the
refrigeration system.
d. Defective or stuck water regulating valve: Check its
operation.
e. High water temperature entering condenser:
Check cooling tower fan for broken belt(s) and
cooling tower for fouling.
f. Insufficient water flow: Check water supply pres-
sure and flow. Check circulating pump and system
for obstructions, fouling or leaks.
g. Incorrectly set water regulating valve: Check its
setting.
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