Carrier 48NLT - Manual (Page 11)

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a refrigerant leak. Leak-test all refrigerant tubing con­
nections using electronic leak detector, or liquid-
soap solution. If a refrigerant leak is detected, see
Start-Up, Check for Refrigerant Leaks section.
c. Inspect all field- and factory-wiring connections. Be
sure that connections are completed and tight.
d. Inspect coil fins. If damaged during shipping and han­
dling, carefully straighten fins with a fin comb.
3. Verify the following conditions:
A WARNING
Do not purge gas supply into the combustion cham­
ber. Do not use a match or other open flame to
check for gas leaks. Failure to follow this warning
could result in an explosion causing personal injury
or death.
a. Make sure that gas supply has been purged, and that
all gas piping has been checked for leaks.
b. Make sure that outdoor-fan blade is correctly posi­
tioned in fan orifice. Blades should clear fan motor
by no more than V 4 inch.
c. Make sure that air filter(s) is in place.
d. Make sure that condensate drain pan and trap are filled
with water to ensure proper drainage.
e. Make sure that all tools and miscellaneous loose parts
have been removed.
START-UP
Check for Refrigerant Leaks — Proceed as follows
to locate and repair a refrigerant leak and to charge the unit;
1. Locate leak and make sure that refrigerant system pres­
sure has been relieved.
2. Repair leak following accepted practices.
NOTE; Install a filter drier whenever the system has been
opened for repair.
3. Add a small charge of R-22 refrigerant vapor to system
and leak-test unit.
4. Evacuate refrigerant system if additional leaks are not
found.
5. Charge unit with R-22 refrigerant, using a volumetric-
charging cylinder or accurate scale. Refer to unit rating
plate for required charge. Be sure to add extra refrig­
erant to compensate for internal volume of filter drier.
Start-Up Heating Section and Make
Follow the lighting instructions on the heating section op­
eration label (located inside the burner access door) to start
the heating section.
When lighting the unit for the first time, perform the
following:
If the gas supply pipe was not purged before connecting
the unit, it will be full of air. It is recommended that the
ground joint union be loosened, and the supply line be al­
lowed to purge until the odor of gas is detected. Never purge
gas lines into a combustion chamber. Immediately upon de­
tection of gas odor, retighten the union. Allow 5 minutes to
elapse, then light unit using the following steps.
CHECK HEATING CONTROL - Start and check the unit
for proper heating control operation as follows: (See fur­
nace lighting instructions located inside burner access panel.)
1. Place the room thermostat SYSTEM switch in the HEAT
position and the fan switch in the AUTO, position.
2. Set the heating temperature control of the thermostat above
room temperature.
3. Observe that after built-in time delays, the pilot auto­
matically lights, the burners light and the blower motor
starts.
4. Observe that the burners and pilot go out, and that after
a built-in delay the blower motor stops when the heating
control setting of the thermostat is satisfied.
NOTE: The 060-size 460-v models are equipped with a 3-
phase blower motor. Check blower wheel for correct rota­
tion as indicated by arrow on blower housing. If blower
wheel rotates in opposite direction, reverse any 2 blower
motor leads or any 2 line voltage leads. Recheck blower
wheel rotation if necessary to reverse leads.
CHECK GAS INPUT — Check gas input and manifold pres­
sure after unit start-up. (See Table 4.) If adjustment is re­
quired, proceed as follows.
The rated gas inputs shown in Table 4 are for altitudes
from sea level up to 2000 ft above sea level. These inputs
are based on natural gas with a heating value of 1050 Btu/
ft^ at 0.65 specific gravity, or propane gas with a heating
value of 2500 Btu/fr at 1.5 specific gravity. For elevations
above 2000 ft, reduce input 4% for each 1000 ft above sea
level. When the gas supply being used has a different heat­
ing value or specific gravity, refer to national and local codes,
or contact your Distributor or Branch to determine the re­
quired orifice size.
Adjustments
A CAUTION
A CAUTION These units are designed to consume the rated gas in­
puts using the fixed orifices at specified manifold pres­
sures as shown in Table 4. DO NOT REDRILL THE
ORIFICES UNDER ANY CIRCUMSTANCES.
Complete the required procedures given in Start-Up sec­
tion before starting the unit.
Do not jumper any safety devices when operating the unit.
Make sure that burner orifices are aligned properly. Un­
stable operation may occur when the burner orifices in the
manifold are misaligned.
NOTE: When installing a unit in extremely cold climate
areas, a run-in period for the inducer motor is recom­
mended. After the unit is installed, disconnect the red wire
from terminal 2 at the ignition control (IGN) and jumper
terminals R-W at the control voltage terminal board. The
inducer motor should run but the burner will not ignite. Al­
low inducer motor to run for 4 to 5 hours. Reconnect red
wire to terminal 2 at IGN and remove R-W jumper at the-
control voltage terminal board. Proceed as follows to com­
plete heating section start-up.
ADJUST GAS INPUT — The gas input to the unit is de­
termined by measuring the gas flow at the meter or by mea­
suring the manifold pressure. Measuring the gas flow at the
meter is recommended for natural gas units. The manifold
pressure must be measured to determine the input of pro­
pane gas units.
Measure Gas Flow (Natural Gas Units') — Minor adjust­
ment to the gas flow can be made by changing the manifold
pressure. The manifold pressure must be maintained be­
tween 3.2 and 3.8 in. wg. If larger adjustments are
required, change main burner orifices following the recom­
mendations of national and local codes.
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