Carrier 58SX040 - Manual (Page 7)

PILOT FLAME BURNER FLAME
Fig. 7 — Proper Pilot and Burner Flames
NOTE; Manifold pressure must always be measured with
burner enclosure front removed. The gas meter must
always be clocked with burner enclosure front installed.
c. Replace burner enclosure front and measure
adjusted gas input rate using method outlined in
step 1.
d. Replace cap that conceals gas valve regulator
adjustment screw.
A CAUTION
Be sure burner enclosure front is in place after
adjustments have been made.
3. Look through sight glass in burner enclosure and
check burner and pilot flame The main burner flame
should be clear blue, almost transparent. The pilot
flame should be well defined. See Fig 7.
4. High Altitude — Input ratings apply for altitudes up
to 2000 feet. Ratings for altitudes above 2000 ft must
be 4% less for each 1000 ft above sea level.
Temperature Rise — Do NOT operate furnace
outside range of temperature rise specified on unit rating
plate Determine air temperature rise as follows;
1. Place thermometers in return and supply ducts as near
furnace as possible. Thermometers must not “see”
heating element or radiant heat may affect readings.
This practice is particularly important with straight-
run ducts.
2. When thermometer readings stabilize, subtract return-
air temperature from supply-air temperature to
determine air temperature rise.
3. Adjust temperature rise by adjusting blower speed.
Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise.
Thermostat Heat Anticipator Adjustment —
Thermostat heat anticipator must be set to match amp
draw of components in R-W circuit. Accurate amp draw
measurements can be obtained at thermostat subbase
terminals R and W. Figure 8 illustrates an easy method
of obtaining these measurements. Amp reading should
be taken after blower has started on its heating speed.
Safety Check of Limit Control — Control shuts off
combustion gas supply and energizes circulating-air
blower motor if furnace overheats.
Recommended method of checking this limit control is
to gradually block off return air after furnace has been
operating for at least 5 minutes. As soon as limit control
functions, return-air opening should be unblocked to
Fig. 8 — Amp Draw Measurements
permit normal air circulation. By using this method to
check limit control, proper functioning can be determined
and furnace will fail-safe if circulating air supply is
restricted or motor fails. If limitcontrol does notfunction
during this test, identify and correct cause of malfunction.
Safety Check of Flow-Sensing Switch — This
control proves operation of draft inducer Check switch
operation as follows;
1. Turn off 1 15-V powei to furnace
2 Remove control access panel and disconnect inducer-
motor lead wires from inducer printed-circuit board
3. Turn on 115-V power to furnace.
4. Close thermostat switch as if making normal furnace
start When flow-sensing switch is functioning
properly, gas should not flow to pilot and ignitor
should not operate. If either pilot gas flow or ignitor
operation occurs when inducer motor is disconnected,
shut furnace down immediately. Determine cause of
malfunction and correct condition.
5. Turn off 115-V power to furnace.
6.
Reconnect inducer-motor leads, reinstall control
access panel, and turn on 115-V power supply.