37
MAINTENANCE
Cleaning
The unit should be thoroughly cleaned inside and out. Frequency
of cleaning will depend on unit location and area conditions.
Drains must be kept free of dirt and trash. Coils can be cleaned
with a stiff bristle (not wire) brush or vacuum cleaner. Coils can be
reached through access panels.
Inspection
Check coil baffles for tight fit to prevent air from bypassing the
coil. Check panels for air leakage, particularly those sealing the
fan and coil compartments. Check for loose electrical connections,
proper refrigerant charge, and refrigerant piping leaks.
Condensate Drain
The drain pan and trap should be cleaned at least twice per year.
After cleaning, test the condensate drain for proper operation by
pouring a bucket of water into the condensate drain pan. The water
should flow out immediately and evenly.
Water-Cooled Condensers
Water-cooled condensers may require cleaning of scale (water de-
posits) due to improperly maintained closed-loop water systems.
Sludge build-up may need to be cleaned in an open water tower
system due to induced contaminants.
Local water conditions may cause excessive fouling or pitting of
tubes. Condenser tubes should therefore be cleaned at least once a
year, or more often if the water is contaminated.
Proper water treatment can minimize tube fouling and pitting. If
such conditions are anticipated, water treatment analysis is recom-
mended. Refer to the Carrier System Design Manual, Part 5, for
general water conditioning information.
Clean condensers with an inhibited hydrochloric acid solution.
The acid can stain hands and clothing, attack concrete, and, with-
out inhibitor, attack steel. Cover surroundings to guard against
splashing. Vapors from vent pipe are not harmful, but take care to
prevent liquid from being carried over by the gases. Warm solu-
tion acts faster, but cold solution is just as effective if applied for a
longer period.
GRAVITY FLOW METHOD (FIG. 32)
Do not add solution faster than vent can exhaust the generated gas-
es. When condenser is full, allow solution to remain overnight,
then drain condenser and flush with clean water. Follow acid man-
ufacturer’s instructions.
FORCED CIRCULATION METHOD (FIG. 33)
Fully open vent pipe when filling condenser. The vent may be
closed when condenser is full and pump is operating. Regulate
flow to condenser with a supply line valve. If pump is a nonover-
loading type, the valve may be fully closed while pump is running.
For average scale deposit, allow solution to remain in condenser
overnight. For heavy scale deposit, allow 24 hours. Drain con-
denser and flush with clean water. Follow acid manufacturer’s
instructions.
Fig. 32 — Gravity Flow Method
Fig. 33 — Forced Circulation Method
Cleaning Heating Coils
If proper filtration is maintained in the unit it should not be neces-
sary to clean heating coils. However, if the coils become dirty or
greasy, film forms on the fins. Proper cleaning can restore the coil
heating performance.
For best results wash coils from discharge side and wash back to-
ward the fan or unit return filters. Clean coils with a vacuum
cleaner, fresh water, compressed air, or a bristle brush (not wire).
Backflush coil to remove debris. Commercial coil cleaners may
also be used to help remove grease and dirt. Steam cleaning is
NOT recommended. Units installed in corrosive environments
should be cleaned as part of a planned maintenance schedule. In
this type of application, all accumulations of dirt should be
cleaned off the coil.
Use a fin comb with teeth of the correct fin spacing when straight-
ening bent or mashed fins.
Cleaning Steam Coils
If proper filtration is maintained in the unit it should not be neces-
sary to clean steam coils. However, if the coils become dirty or
greasy, film forms on the fins. Proper cleaning can restore the coil
heating performance.
CAUTION
To prevent personal injury, follow all safety codes. Wear
safety glasses and rubber gloves when using inhibited hy-
drochloric acid solution. Observe and follow acid manufac-
turer's instructions.
PAIL
FUNNEL
1"
PIPE
5' APPROX
CONDENSER
FILL CONDENSER WITH
CLEANING SOLUTIONS,
DO NOT ADD SOLUTION
MORE RAPIDLY THAN
VENT CAN EXHAUST
GASSES CAUSED BY
CHEMICAL REACTION.
VENT
PIPE
3' TO 4'
PAIL
CONDENSER
REMOVE WATER
REGULATING VALVE
RETURN
1" PIPE
SUPPLY
GAS VENT
GLOBE
VALVES
PRIMING
CONN
PUMP
SUCTION
PUMP
SUPPORT
TANK
FINE MESH
SCREEN
