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Table 1 — Physical Data
UNIT SIZE 48
NLT018
NLT024
NHT024
NLT030
NMT030
NHT030
NLT036
NMT036
NET036
NHT036
NVT036
NOMINAL CAPACITY (ton)
11/2
:
_
?
_I I
2V2
I I_
!
_
OPERATING WEIGHT (lb)
450
454
I
I
460
I 1
470
1
476
1
480
1 I
486
I
490
I
490
1 i
530
1
536
COMPRESSORS
Reciprocating Hermetic. 3500 Rpm
Quantity
1
REFRIGERANT*
R-22
REFRIGERANT METERING DEVICE
AccuRater® Piston
CONDENSER COIL
Rows
1 I
2
Fins/in.
I
I
20
CONDENSER FAN
Nominal Airflow (Cfm)
2000
2500
3000tt
825**
Nominal Speed (Rpm)
825
1100
1100tt
Quantity ...Diameter (in.)
Motor Hp (single-phase)
Vio
1
20
^
1/4
1/10
(three-phase)
-
V4
EVAPORATOR COIL
Rows
3
Fins/In.
14
EVAPORATOR FAN
Nominal Cfm
600
I I
800
I
1
1000
1 1
1200
1 1
1200
Nominal Speed (Rpm)
1100
Diameter x Width (in.)
lOx 8
10
X
10
Motor Hp (single-phase)
V3
V2
%
(three-phase)
—
Va
3/4
FURNACE SECTION
Burner Orifice No. (Qty...drlll size)
2 44
2 44
3 44
2. 44
3 44
4 44
3 44
4 44
4 42
5.44
6 .44
Natural Gas
Burner Orifice No. (Qty...drill size)
2. 55
2 55
3 55
2 55
3 55
4 55
3,55
4 55
4 54
5 55
6 55
Propane Gas
Pilot Orifice Diameter (in. ...drill size)
nifl 77
Natural Gas
Pilot Orifice Diameter (in.)
nnp
Propane Gas
RETURN-AIR FILTERS (sq ln.)t
1
1
Disposable
288
528
624
720
Cleanable
192
352
416
480
'Operating charge is iisted on unit namepiate
fRequired fieid-supplied filter areas are based on the iarger of the ARi-rated (Air Conditioning & Refrigeration institute) cooling airfiow or the heating
airflow at a velocity of 300 ft/min for disposable type or 450 ft/min for high-capacity type Air filter pressure drop must not exceed 0.08 in wg
"Single-phase units
ttThree-phase units
Step 2 - Provide Unit Support
ROOF CURB — Install accessory roof curb in accordance
with instructions shipped with curb. Install insulation, cant
strips, roofing and flashing. Ductwork must be attached to
curb.
IMPORTANT: The gasketing of the unit to the roof
curb is critical for water integrity. Install gasketing
material supplied with the roof curb. Improperly ap¬
plied gasketing also can result in air leaks and poor
unit performance.
Curb should be level to within 14 inch. This is necessary
for unit drain to function properly. Refer to Accessory Roof
Curb Installation Instructions for additional information as
required.
SLAB MOUNT — Place the unit on a solid, level concrete
pad that is a minimum of 4-in. thick with 2-in. above grade.
The slab should extend approximately 2-in. beyond the cas¬
ing on all 4 sides of the unit. Install a gravel apron in front
of condenser-air inlets to prevent obstruction of airflow by
grass or shrubs. Do not secure the unit to the slab except
when required by local codes.
Step 3 — Provide Clearances
— The required min¬
imum operating and service clearances are shown in Fig. 2
and 3. Adequate combustion, ventilation and condenser air
must be provided.
The condenser fan discharges through the top of the unit.
Be sure that the fan discharge does not recirculate to the
condenser coil. Do not locate the unit in either a corner or
under an overhead obstruction. The minimum clearance
under a partial overhang (such as a normal house overhang)
is 48-in. above the unit top. The maximum horizontal ex¬
tension of a partial overhang must not exceed 48 inches.
A CAUTION
Do not restrict condenser airflow. An air restriction at
either the outdoor-air inlet (the entire surface of the out¬
door coil) or the fan discharge can be detrimental to
compressor life.
Do not place the unit where water, ice or snow from an
overhang or roof will damage or flood the unit. Do not in¬
stall the unit on carpeting, tile or other combustible mate¬
rials. The unit may be installed on wood flooring or on Class
A, B or C roof covering materials.
Step 4 — Rig and Place Unit
— Use spreader bars
and crate top when rigging the unit. The units must be rigged
for lifting as shown in Fig. 4. Refer to Fig. 4 for rigging
weight and Table 1 for operating weight. Use extreme cau¬
tion to prevent damage when moving the unit. Unit must
remain in an upright position during all rigging and mov¬
ing operations. The unit must be level for proper conden¬
sate drainage; therefore, the ground-level pad or accessory
roof-mounting curb must be level before setting the unit in
place. When a field-fabricated support is used, be sure that
the support is level and properly supports the unit.
A
CAUTION
When installing the unit on a rooftop, be sure the roof
will support the additional weight. Refer to Fig. 4 for
corner weight information.
4
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