Carrier 48NHT024 - Page 17

Table 14—Model 48NT060 (Belt Drive) Air Delivery (Cfm) At Indicated External
Static Pressure (in. W.C.) (Dry Coil without Air Filter*)
End Discharge
F EXTERNAL STATIC PRESSURE-INCHES WATER
RPM
PULLEY TURNS
! 208V
1 230V or 460V
OPEN
0.0
0.2
0.4
0.6
0.8
0.0
0.2
0.4
0.6 0.8
1430
1 See Note #2
2761
2534
2343
2152
1965
2808
2588
2331
2189 2007
1380
2
2685
2444
2230
2035
1829
2716
2498
2282
2075 1864
1330
3
2583 2341
2129
1921
—
2585
2355
2154
1921
1280 4
2445
2174
1960
— —
2454
2209
1966
1733
_
1230
5
2287
1964
1775
—
—
2287
2028
1780
—
—
Table 15—Model 48NT060 (Belt Drive) Air Delivery (Cfm) At Indicated External
Static Pressure (in. W.C.) (Dry Coil without Air Filter*)
Down Discharge
PULLEY TURNS
EXTERNAL STATIC PRESSURE—INCHES WATER
RPM
208V
230V or 460V
OPEN
0.0
0.2
0.4
0.6
0.8
0.0
0.2
0.4
0.6
0.8
1430
1 See Note #2
2623
2407
2225
2044
1867
2667
2458
2243
2078
1906
1380 2
2551
2322
2118
1933
1737
2580
2373
2168
1971
1771
1330
3
2454
2221
2022
1825
—
2465
2237
2046
1825
_
1280
4
2323
2065
1862
— —
2331
2098 1867
_ _
1230
^5
2272
1866
—
—
—
2173
1927
—
— —
NOTES: 1. Factory setting is 4 turns open.
2. Do not operate blower below 1 turn open on motor pulley. Motor overheating may result.
3. Do not operate unit in cooling mode at airflow rate below 1750 cfm. Indoor coil icing may occur.
* Air delivery values are without air filter. Air delivery values are for dry coil. See Table 16, page 10 for coil pressure drop. Deduct field supplied filter pressure
drop and wet coil pressure drop to obtain external static pressure available for ducting.
Table 16—Wet Coll Pressure Drop
Airflow
(CFM)
Pressure Drop
(in. w.c.)
650
0.038
850
0.046
1050
0.066
1250
0081
1450
0.111
1650
0.129
1850
0.150
2050
0.180
2250
0.198
A, Air Filter
Never operate the unit without a suitable air filter in
the return-air duct system. Always replace the filter
with the same dimensional size and type as originally
installed. See Tables 2 thru 7 for recommended filter
sizes.
Inspect air filter(s) at least once each month and replace
(disposable-type) or clean (cleanable-type) at least twice dur¬
ing each heating and cooling season or whenever the filter(s)
becomes clogged with dust and lint.
Replace filters with the same dimensional size and type as
originally provided, when necessary.
B. Unit Top Removal
A CAUTION
Condenser fan and motor are fastened to the unit top.
When removing the top, use extreme care to not pull
the fan motor leads loose.
NOTE: When performing maintenance or service procedures
that require removal of the unit top, be sure to perform all
of the routine maintenance procedures that require top
removal, including: inspection of the heat exchanger area,
coil inspection and cleaning, and condensate drain pan
inspection and cleaning.
Only qualified service personnel should perform mainte¬
nance and service procedures that require unit top removal.
Refer to the following top removal procedures:
1. Turn off gas supply, then turn off electric power to
unit.
2. Remove all screws that secure unit top, including
screws around four sides and those on top that screw
into internal divider panels. Save all screws.
3. Tape all side panels at each seam near unit top. Use
tape strips that are at least 5-ins. long to prevent sides
from falling when top is removed.
4. Lift top from unit carefully. Set top on edge and ensure
that top is supported by unit side that is opposite duct
(or plenum) side. Use extreme care to prevent damage
to the fan blades, motor, and insulation.
5. Carefully replace and secure unit top to unit, using
screws removed in step 3, when maintenance and/or
service procedures are concluded. (Be sure to use origi¬
nal screws that have rubber washers to seal out water
when securing top to internal divider panels.)
C. Evaporator Blower and Motor
For longer life, operating economy, and continuing effi¬
ciency; clean accumulated dirt and grease from the blower
wheel and motor annually.
Lubricate the motor every 5 years if the motor is used inter¬
mittently (thermostat FAN switch in AUTO position), or
every 2 years if the motor is used continuously (thermostat
FAN switch in ON position).
A WARNING
Turn off the gas supply, then disconnect and tag electri¬
cal power to the unit before cleaning and lubricating the
blower motor and wheel. Failure to adhere to this warn¬
ing could cause personal injury or death.
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