36
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 vac-
uum 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, particu-
larly those sealing the fan and coil compartments. Check for
loose electrical connections, proper refrigerant charge, and re-
frigerant piping leaks.
Condensate Drain —
The drain pan and trap should be
cleaned at least twice per year. After cleaning, test the conden-
sate drain for proper operation by pouring a bucket of water
into the condensate drain pan. The water should flow out im-
mediately and evenly.
Water-Cooled Condensers —
Water-cooled con-
densers may require cleaning of scale (water deposits) 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 pit-
ting 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 pit-
ting. If such conditions are anticipated, water treatment analy-
sis is recommended. Refer to the Carrier System Design Manu-
al, Part 5, for general water conditioning information.
Clean condensers with an inhibited hydrochloric acid solu-
tion. The acid can stain hands and clothing, attack concrete,
and, without 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 solution acts faster, but cold solution is just as ef-
fective if applied for a longer period.
GRAVITY FLOW METHOD (Fig. 32) — Do not add solu-
tion faster than vent can exhaust the generated gases. When
condenser is full, allow solution to remain overnight, then drain
condenser and flush with clean water. Follow acid manufactur-
er’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 nonoverload-
ing type, the valve may be fully closed while pump is running.
For average scale deposit, allow solution to remain in con-
denser overnight. For heavy scale deposit, allow 24 hours.
Drain condenser and flush with clean water. Follow acid manu-
facturer’s instructions.
Cleaning Heating Coils —
If proper filtration is main-
tained in the unit it should not be necessary 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 toward 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 corro-
sive environments should be cleaned as part of a planned main-
tenance 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
straightening bent or mashed fins.
CAUTION
To prevent personal injury, follow all safety codes. Wear
safety glasses and rubber gloves when using inhibited
hydrochloric acid solution. Observe and follow acid manu-
facturer's instructions.
,
Fig. 32 — Gravity Flow Method
a50-8520
Fig. 33 — Forced Circulation Method
a50-8521