Filter
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a. Before lighting the unit for the first time, perform the
following: If the gas supply pipe was not purged be-
fore connecting the unit, it will be full of air. It is rec-
ommended that the ground joint union be loosened,
and the supply line be allowed to purge until the odor
of gas is detected. Never purge gas lines into a com-
bustion chamber. Immediately upon detection of gas
odor, retighten the union. Allow 5 minutes to elapse,
then light unit.
b. Make sure that condenser-fan blade is correctly posi-
tioned in fan orifice. Leading edge of condenser-fan
blade should be
1
⁄
2
in. maximum from plastic fan ori-
fice (see Fig. 23).
c. Make sure that air filter(s) is in place.
d. Make sure that condensate drain trap is filled with wa-
ter 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 and reclaimed from both high- and
low-pressure ports.
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 and reclaim refrigerant from 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 refrigerant
to compensate for internal volume of filter drier.
Start Up Heating Section and Make
Adjustments
Complete the required procedures given in Pre-Start-Up
section on page 22 before starting the unit.
Do not jumper any safety devices when operating the unit.
Make sure that burner orifices are properly aligned. Un-
stable 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 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. The induced-draft motor will start.
4. After a call for heating, the main burner should light with-
in 5 seconds. If the burners do not light, there is a
22-second delay before another 5-second try. If the burn-
ers still do not light, this sequence is repeated. If the burn-
ers 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 seconds after the flame
has been established. The evaporator fan will turn off
45 seconds after the thermostat has been satisfied.
CHECK GAS INPUT — Check gas input and manifold pres-
sure after unit start-up. (See Table 5.) If adjustment is
required proceed as follows.
The rated gas inputs shown in Table 5 are for al-
titudes from sea level to 2000 ft above sea level. These in-
puts 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% 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 in-
puts using the fixed orifices at specified manifold pres-
sures as shown in Table 5. 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 mani-
fold pressure must be measured to determine the input of
propane gas units.
Fig. 23 — Fan Blade Clearance
23