NOTE: The tubes must be inserted and held in a position
perpendicular to the air flow so that velocity pres-
sure does not affect the static pressure readings.
3. Using an inclined manometer, determine the pressure drop
across a dry indoor coil. Since the moisture on an indoor
coil may vary greatly, measuring the pressure drop across
a wet coil under field conditions would be inaccurate. To
assure a dry coil, the compressors should be de-energized
while the test is being run.
4. Knowing the pressure drop across a dry coil, the actual
airflow through the unit can be determined from the curve
in Figure 7.
WARNING: Failure to properly adjust the total system air quan-
tity can result in poor system performance.
After readings have been obtained, remove the tubes and
replace the dot plugs in the side panels. Eight millimeter (5/16")
dot plugs (P/N 029-13880) are available through normal parts
ordering procedures.
NOTE: DE-ENERGIZE THE COMPRESSORS BEFORE
TAKING ANY TEST MEASUREMENTS TO ASSURE
A DRY INDOOR COIL.
0.6
0.4
8
11
14
17
20
23
26
DCE036
0.5
0.3
0.2
0.1
0.0
DCE048
DCE060,076
NOMINAL CFM (HUNDREDS)
PR
ESSUR
E
D
R
OP
(IWG
)
149
124
99
74
50
25
0
NOMINAL M
3
/S
0.38
0.52
0.66
0.80
0.94
1.08
1.23
PR
ESSUR
E
D
R
OP
(P
A)
FIG. 7 - PRESSURE DROP ACROSS A DRY
EVAPORATOR COIL VS SUPPLY AIRFLOW
SECURE OWNER’S APPROVAL
:
When the system is functioning properly, secure the owner’s approval. Show him
the location of all disconnect switches and the thermostat. Teach him how to start and stop the unit and how to adjust tem-
perature settings within the limitations of the system.
MAINTENANCE
NORMAL MAINTENANCE
WARNING: Prior to any of the following maintenance proce-
dures, shut off all power to the unit to prevent
personal injury.
FILTERS - Inspect once a month. Replace disposable or clean
permanent type as necessary. DO NOT replace permanent
type with disposable filters.
MOTORS - Indoor fan and outdoor fan motors are permanently
lubricated and require no maintenance.
OUTDOOR COIL - Dirt should not be allowed to accumulate
on the outdoor coil surface or other parts in the air circuit.
Cleaning should be as often as necessary to keep coil clean.
Use a brush, vacuum cleaner attachment, or other suitable
means. If water is used to clean coil, be sure power to the unit
is shut off prior to cleaning.
NOTE: Exercise care when cleaning the coil so that the coil
fins are not damaged.
Do not permit the outdoor air discharge to be obstructed by
overhanging structures or shrubs.
530.26-N1YI
14
Unitary Products Group
