Operating instructions
unit is operating. For propane applications, the gas pressure must
not be less than 7.0 in. wg or greater than 13 in. wg at the unit
connection.
An 1/8-in. NPT plugged tapping, accessible for test gage connec-
tion, must be installed immediately upstream of the gas supply
connection to the gas valve.
When installing the gas supply line, observe local codes pertaining
to gas pipe installations. Refer to the NFGC ANSI Z223.1-1988
NFPA latest edition (in Canada, CAN/CGA B149.1, (2)-M86). In
the absence of local building codes, adhere to the following
pertinent recommendations:
1. Avoid low spots in long runs of pipe. Grade all pipe 1/4 in. in
every 15 ft to prevent traps. Grade all horizontal runs
downward to risers. Use risers to connect to heating section
and to meter.
2. Protect all segments of piping system against physical and
thermal damage. Support all piping with appropriate straps,
hangers, etc. Use a minimum of one hanger every 6 ft. For
pipe sizes larger than 1/2 in., follow recommendations of
national codes.
3. Apply joint compound (pipe dope) sparingly and only to male
threads of joint when making pipe connections. Use only pipe
dope that is resistant to action of liquefied petroleum gases as
specified by local and/or national codes. Never use Teflon
tape.
4. Install sediment trap in riser leading to heating section (See
Fig. 9). This drip leg functions as a trap for dirt and
condensate.
5. Install an accessible, external, manual main shutoff valve in
gas supply pipe within 6 ft of heating section.
6. Install ground-joint union close to heating section between
unit manual shutoff and external manual main shut-off valve.
7. Pressure-test all gas piping in accordance with local and
national plumbing and gas codes before connecting piping to
unit.
NOTE: Pressure test the gas supply system after the gas supply
piping is connected to the gas valve. The supply piping must be
disconnected from the gas valve during the testing of the piping
systems when test pressure is in excess of 0.5 psig. Pressure test
the gas supply piping system at pressures equal to or less than 0.5
psig. The unit heating section must be isolated from the gas piping
system by closing the external main manual shutoff valve and
slightly opening the ground-joint union.
Unstable operation may occur when the gas valve and
manifold assembly are forced out of position while connect-
ing improperly-routed rigid gas piping to the gas valve. Use
a backup wrench when making connection to avoid strain on,
or distortion of, the gas control piping.
If a flexible conductor is required or allowed by the authority
having jurisdiction, black iron pipe shall be installed at the
gas valve and shall extend a minimum of 2 in. outside the unit
casing.
Table 2—Physical Data—Unit 48GX
UNIT SIZE 48GX 024040 024060 030040 030060 036060 036090 042060 042090
NOMINAL CAPACITY (ton) 2 2 2½ 2½ 3 3 3½ 3½
OPERATING WEIGHT (lb.) 290 290 313 313 321 321 382 382
COMPRESSORS
Quantity
Scroll
1
REFRIGERANT (R-22)
Quantity (lb.)
3.4 3.4 4.4 4.4 5.2 5.2 6.4 6.4
REFRIGERANT METERING DEVICE
Orifice ID (in.)
.034 .034 .030 .030 .032 .032 .034 .034
CONDENSER COIL
Rows...Fins/in.
Face Area (sq ft)
1...17
9.1
1...17
9.1
1...17
12.7
1...17
12.7
2...17
9.1
2...17
9.1
2...17
12.3
2...17
12.3
CONDENSER FAN
Nominal Cfm
Diameter (in.)
Motor Hp (Rpm)
2350
22
1/8 (825)
2350
22
1/8 (825)
2350
22
1/8 (825)
2350
22
1/8 (825)
2350
22
1/8 (825)
2350
22
1/8 (825)
3300
22
1/8 (825)
3300
22
1/8 (825)
EVAPORATOR COIL
Rows...Fins/in.
Face Area (sq ft)
3...15
3.1
3...15
3.1
3...15
3.1
3...15
3.1
3...15
3.7
3...15
3.7
3...15
4.7
3...15
4.7
EVAPORATOR BLOWER
Nominal Airflow (Cfm)
Size (in.)
Motor Hp (Rpm)
800
10X10
1/4 (1075)
800
10X10
1/4 (1075)
1000
10X10
1/4 (1075)
1000
10X10
1/4 (1075)
1200
11X10
1/2 (1075)
1200
11X10
1/2 (1075)
1400
11X10
3/4 (1075)
1400
11X10
3/4 (1075)
FURNACE SECTION*
Burner Orifice No. (Qty...Drill Size)
Natural Gas
Burner Orifice No. (Qty...Drill Size)
Propane Gas
2...44
2...50
2...38
2...46
2...44
2...50
2...38
2...46
2...38
2...46
3...38
3...46
2...38
2...46
3...38
3...46
RETURN-AIR FILTERS (in.)†
Throwaway
20X20 20X20 20X20 20X20 20X24 20X24 24X30 24X30
* Based on altitude of 0 to 2000 ft.
† Required filter sizes shown are based on the larger of the ARI (Air Conditioning and Refrigeration Institute) rated cooling airflow or the heating airflow velocity of 300
ft/minute for high-capacity type. Air filter pressure drop for non-standard filters must not exceed 0.08 in. wg.
9