Operating instructions

4. Recover refrigerant from refrigerant system and evacuate to
500 microns 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 refrigerant to
compensate for internal volume of filter drier.
Step 2—START-UP HEATING AND MAKE ADJUST-
MENTS
Complete the required procedures given in the Pre-Start-Up
section before starting the unit.
Do not jumper any safety devices when operating the unit.
Make sure that burner orifices are properly aligned. Unstable
operation may occur when the burner orifices in the manifold are
misaligned.
Follow the lighting instructions on the heating section operation
label (located inside the burner or blower access door) to start the
heating section.
NOTE: Make sure that gas supply has been purged, and that all
gas piping has been checked for leaks.
CHECK HEATING CONTROL
Start and check the unit for proper heating control operation as
follows (see furnace lighting instructions located inside burner or
blower access panel):
1. Place room thermostat SYSTEM switch in the HEAT position
and the fan switch is placed in AUTO. position.
2. Set the heating temperature control of the thermostat above
room temperature.
3. The induced-draft motor will start.
4. After a call for heating, the main burner should light within 5
sec. If the burners do not light, there is a 22-sec. delay before
another 5-sec. try. If the burners still do not light, this
sequence is repeated. If the burners do not light within 15
minutes from the initial call for heat, there is a lockout. To
reset the control, break the 24-v power to W.
5. The evaporator fan will turn on 45 sec. after the flame has
been established. The evaporator fan will turn off 45 sec. after
the thermostat has been satisfied.
CHECK GAS INPUT
Check gas input and manifold pressure after unit start-up (See
Table 6). If adjustment is required proceed as follows:
• The rated gas inputs shown in Table 6 are for altitudes from sea
level to 2000 ft above sea level. These inputs are based on
natural gas with a heating value of 1050 Btu/ft
3
at 0.65 specific
gravity, or propane gas with a heating value of 2500 Btu/ft
3
at
1.5 specific gravity.
• For elevations above 2000 ft, reduce input 4 percent for each
1000 ft above sea level.
• When the gas supply being used has a different heating value or
specific gravity, refer to national and local codes, or contact
your distributor to determine the required orifice size.
These units are designed to consume the rated gas inputs
using the fixed orifices at specified manifold pressures as
shown in Table 6. DO NOT REDRILL THE ORIFICES
UNDER ANY CIRCUMSTANCES.
ADJUST GAS INPUT
The gas input to the 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. The
manifold pressure must be measured to determine the input of
propane gas units.
Measure Gas Flow (Natural Gas Units)
Minor adjustment to the gas flow can be made by changing the
manifold pressure. The manifold pressure must be maintained
between 3.4 and 3.6 in. wg.
If larger adjustments are required,
change main burner orifices following
the 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 the meter.
Proceed as follows:
1. Turn off gas supply to unit.
2. Remove pipe plug on manifold (See Fig. 13) and connect
manometer. Turn on gas supply 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.
6. Multiply result of Step 5 by Btu heating value of gas to obtain
total measured input in Btuh. Compare this value with heating
input shown in Table 6 (Consult the local gas supplier if the
heating value of gas is not known).
EXAMPLE: Assume that the size of test dial is 1 cu ft, one
revolution takes 32 sec., and the heating value of the gas is 1050
Btu/ft
3
. Proceed as follows:
1. 32 sec. to complete one revolution.
2. 3600 ÷ 32 = 112.5.
3. 112.5 x 1 =112.5 ft
3
of gas flow/hr.
4. 112.5 x 1050 = 118,125 Btuh input.
If the desired gas input is 115,000 Btuh, only a minor change in the
manifold pressure is required.
Observe manifold pressure and proceed as follows to adjust gas
input:
1. Remove cover screw over regulator adjustment screw on gas
valve.
Fig. 14—Monoport Burner
C99021
MANIFOLD
BURNER
BURNER FLAME
16