StyleCrest Installation Manual

20
readings, the thermometer on the supply air side must be
shielded from direct radiation from the heat exchanger.
2. Adjust all registers and duct dampers to the desired
position and run the furnace for 10 to 15 minutes in
high fire before taking any temperature readings. The
temperature rise is the difference between the supply
and return air temperatures.
For typical duct systems, the temperature rise will fall
within the limits specified on the rating plate with the
blower speed at the factory recommended setting. If
the measured temperature rise is outside the specified
limits, it may be necessary to change the speed of the
blower. NOTE: Lowering the blower speed increases the
temperature rise and a higher blower speed will decrease
the temperature rise.
The furnace is equipped with a multi-tap ECM motor. For
alternate motor tap selections see Table 14, (page 26)
& Table 15, (page 27).
Burner Adjustments
CAUTION:
• Adjustment must be made only by a qualified
technician. Improper air adjustment may
cause unsafe operation, explosion and/or fire
asphyxiation.
• If the input to the furnace is too great because
of excessive gas pressure, wrong size nozzle or
orifice, high altitude, etc., the burner flame will
be sooty and can produce carbon monoxide,
which could result in unsafe operation,
explosion and/or fire or asphyxiation.
Burner settings are made at the factory. However, these
settings may change during shipping, handling, and
installation. The following items should be checked and
readjusted if necessary.
Gas Pressure
The gas pressure can be checked with a manometer at
the pressure tap located on the top of the gas valve.
Natural gas manifold pressure should be 3.5” W.C. and
L.P. gas manifold pressure should be 10” W.C. Replace
the gas pressure tap plug on the gas valve. See Figure
27 (page 15).
OPERATING SEQUENCE
Direct Ignition Furnaces
1. On a call for heat, the thermostat contacts close,
supplying 24 VAC between terminals C and W of the
control module.
2. When the inducer starts, the air pressure switch closes
at -0.30 W.C. differential pressure and energizes the
gas valve.
3. After a 45 second purge, the ignitor is energized for a 30
second warm-up period. After warm up, the gas valve
opens. NOTE: The time for ignition is approximately 6
seconds, after which the gas valve either remains open
if flame is sensed, or closes if flame is not sensed.
4. If flame is not sensed, the sequence repeats four more
times before a lockout occurs. To reset, wait 30 seconds
and then interrupt the 24 VAC power by turning the room
thermostat below room temperature, then returning it
to the original set point.
5. If flame does not establish on the 5th attempt (initial
fire + 4 re-tries), the control de-energizes the gas valve,
the red LED flashes 4 times, and the furnace locks out
heat operation for 1 hour. See Table 7, (page 21).
6. If a flame is present, the control energizes the main
blower on heat speed 30 seconds after the gas valve
opens.
WARNING:
Should overheating occur or the gas supply fails
to shut off, shut off the manual gas valve to the
furnace before shutting off the electrical supply.
7. When call for heat is satisfied the thermostat contacts
open, the gas valve shuts off gas flow and the combustion
blower remains on for a 30 second post-purge period.
8. The main blower is de-energized after a 120 second
blower off delay.
TROUBLESHOOTING
High Gas Bills
a. Verify the proper orifice is being used. See Table 6,
(page 16).
b. Check the return air system. Is it clear and free of
blockage?
c. Check the furnace filter. Is it clean or need replacing?
d. Verify the home is insulated, windows and doors fit tightly,
and there are no leaks in the heating duct system.
e. Check the room thermostat. Is the setting higher than
necessary? Low humidity requires higher temperatures
for the same level of comfort. Check for proper humidity
level in the home.
Burner Motor won’t Run - T-stat Calls for Heat
1. Check the electrical supply to the furnace.
2. Verify the furnace On-Off switch is in the ON position.
See Figure 27 (page 15) or Figure 28 (page 20).
3. Defective thermostat circuit - white and red thermostat
low voltage leads. If the combustion fan runs, check:
• Thermostat connections
• Thermostat
Figure 28. Direct Ignition Gas Valve - Honeywell
GAS CONTROL KNOB