Carrier 48KHA - Manual (Page 10)

d. Make sure condensate drain pan is filled with
water to ensure proper drainage.
e. Make sure all tools and miscellaneous loose
parts have been removed.
5. Replace all access panels. Unit is now ready for
initial start-up.
REFRIGERANT LEAKS — Proceed as follows to
repair a refrigerant leak and to charge the unit.
1. Locate leak and ensure that refrigerant system
pressure has been relieved.
2. Repair leak following accepted practices.
NOTE: Install a filter drier whenever 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, such as Dial-a-
Charge, or accurate scale. Refer to unit rating
plate for required charge. Be sure to add extra re­
frigerant to compensate for internal volume of
filter drier.
NOTE: See Cooling Section Start-Up and Adjust­
ments — Checking and Adjusting Refrigerant
Charge.
Heating Section Start-Up and Adjustments
L
Do not jumper any safety devices when operating
unit.
Ensure that burner orifices are properly aligned.
Unstable operation may occur when the burner
orifices in the manifold are misaligned. To ensure
correct burner orifice alignment, check orifice angle
with a machinist’s protractor or other suitable
device. The orifice angle must be from horizontal to
3 degrees down, as measured from unit base.
Follow instructions on heating section operation
label (located in unit near the gas valve) or in
Owner’s Manual, to start the heating section.
CHECKING HEATING CONTROL OPERA­
TION — Start and check unit for proper heating
control operation as follows:
Place room thermostat selector switch in HEAT
position and fan switch in AUTO, position. Set
heating temperature control of thermostat above
room temperature. Observe that after built-in time
delays, the pilot automatically lights, burners light
and blower motor starts. Observe that burners and
pilot are extinguished, and that after a built-in delay,
blower motor stops when heating control setting of
thermostat is satisfied.
GAS INPUT
The rated gas inputs shown in Table 4 are for alti­
tudes from sea level up to 2000 ft above sea level.
These inputs are based on natural gas with a heating
value of 1050Btu/cuft at 0.65 specific gravity, or
propane gas with a heating value of 2500 Btu/cu ft
at 1.5 specific gravity. For elevations above 2000 ft,
reduce input 4% for each 1000 ft above sea level.
When gas supply being used has a different heating
value or specific gravity, refer to Carrier training
manuals, national and local codes, or contact your
Carrier distributor or dealer to determine required
orifice size.
ADJUSTING GAS INPUT — The gas input to unit
is determined by measuring the gas flow at the meter
or by measuring the manifold pressure. Measuring
the gas flow at the meter is recommended for natural
gas units. Manifold pressure must be measured to
determine the input of propane gas units.
Measuring Gas Flow at Meter Method — Natural
Gas Units — Minor adjustment can be made by
changing manifold pressure. Manifold pressure
must be maintained between 3.2 and 3.8 in. wg. If
larger adjustments are required, change main burner
orifices following recommendations of national and
local codes.
NOTE: All other appliances that use the same meter
must be turned off when gas flow is measured at
meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on bottom of gas valve, then
connect water manometer at this point. Turn on
gas to unit.
3. Record number of seconds for gas meter test dial
to make one revolution.
4. Divide number of seconds in step 3 into 3600
(number of seconds in one hour).
5. Multiply result of step 4 by the number of cu ft
shown for one revolution of test dial to obtain
cu ft of gas flow per hour.
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