Water Cooled Condenser Cleaning - Carrier 69NT40-489-100 Series Operation And Service Manual

e. Close and secure condenser fan screen guard.
f. Apply power to unit and check fan rotation. If fan
motor rotates backward, reverse wire numbers 5 and
8.

6.12 WATER COOLED CONDENSER CLEANING

The water-cooled condenser is of the shell and coil type
with water circulating through the cupro-nickel coil. The
refrigerant vapor is admitted to the shell side and is
condensed on the outer surface of the coil.
Rust, scale and slime on the water-cooling surfaces
inside of the coil interfere with the transfer of heat,
reduce system capacity, cause higher head pressures
and increase the load on the system.
By checking the leaving water temperature and the
actual condensing temperature, it can be determined if
the condenser coil is becoming dirty. A larger than
normal difference between leaving condensing water
temperature and actual condensing temperature,
coupled with a small difference in temperature of
entering and leaving condensing water, is an indication
of a dirty condensing coil.
To find the approximate condensing temperature, with
the unit running in the cooling mode, install a gauge 0 to
36.2 kg/cm@ (0 to 500 psig) on the compressor
discharge service valve.
Example: Discharge pressure is 10.3 kg/cm@ (146.4
psig). Referring to Table 19, page 84 (R-134a pressure/
temperature chart), the 10.3 kg/cm@ (146.4 psig) value
converts to 43_C (110_F).
If the water-cooled condenser is dirty, it may be cleaned
and de-scaled by the following procedure:
a. Turn unit off and disconnect main power.
b. Disconnect water pressure switch tubing by loosen-
ing the two flare nuts. Install one-quarter inch flare
cap on water-cooled condenser inlet tube (replaces
tubing flare nut). De-scale tubing if necessary.
What You Will Need:
1. Oakite Aluminum Cleaner
der in 20 kg (44 lb) pails and 205 kg (450 lb) drums.
2. Oakite composition No. 32, available as a liquid in
cases, each containing 3.785 liters (4 U.S. gallon)
bottles and also in carboys of 52.6 kg (116 lbs) net.
NOTE
When Oakite compound No. 32 is being used
for the first time, the local Oakite Technical Ser-
vice representative should be called in for their
suggestions in planning the procedure. The
representative will advise the reader on how to
do the work with a minimum dismantling of
equipment: how to estimate the time and
amount of compound required; how to prepare
the solution; how to control and conclude the
de-scaling operation by rinsing and neutralizing
equipment before putting it back into service.
The representative's knowledge of metals,
types of scale, water conditions and de-scaling
techniques will be highly useful.
3. Fresh clean water.
® 164 available as a pow-
4. Acid proof pump and containers or bottles with rub-
ber hose.
Summary of Procedure:
a. Drain water from condenser tubing circuit.
b. Clean water tubes with Oakite Aluminum Cleaner 164
to remove mud and slime.
c. Flush.
d. De-scale water tubes with Oakite No. 32 to remove
scale.
e. Flush.
f. Neutralize.
g. Flush.
h. Put unit back in service under normal load and check
head (discharge) pressure.
Detailed Procedure:
1. Drain and flush the water circuit of the condenser
coil. If scale on the tube inner surfaces is accompa-
nied by slime, a thorough cleaning is necessary
before de-scaling process can be accomplished.
2. To remove slime or mud, use Oakite Aluminum
Cleaner 164, mixed 170 grams (6 ounces) per 3.785
liters (1 U.S. gallon) of water. Mix cleaner in one half
the volume of water, while stirring, and then add re-
maining water. Warm this solution and circulate
through the tubes until all slime and mud has been
removed.
3. After cleaning, flush tubes thoroughly with fresh
clean water.
4. Prepare a 15% by volume solution for de-scaling, by
diluting Oakite compound No. 32 with water. This is
accomplished by slowly adding 0.47 liter (1 U.S. pint)
of the acid (Oakite No. 32) to 2.8 liters (3 U.S. quarts)
of water.
Oakite No. 32 is an acid. Be sure that the
acid is slowly added to the water. DO NOT
PUT WATER INTO THE ACID - - this will
cause spattering and excessive heat.
Wear rubber gloves and wash the solution
from the skin immediately if accidental con-
tact occurs. Do not allow the solution to
splash onto concrete.
5. Fill the tubes with this solution by filling from the bot-
tom. See Figure 38.
It is important to provide a vent at the top for escaping
gas.
6 Allow the Oakite No. 32 solution to soak in the tube
coils for several hours, periodically pump-circulating
it with an acid-proof pump.
An alternate method may be used whereby a pail
(see Figure 39) filled with the solution and attached
to the coils by a hose can serve the same purpose by
filling and draining. The solution must contact the
scale at every point for thorough de-scaling. Air
pockets in the solution should be avoided by regu-
larly opening the vent to release gas. Keep flames
away from the vent gases.
67
WARNING
WARNING
NOTE
T-305