25
XII. Start-Up and Adjustment
General Operation
This furnace is equipped with an electronic ignition de-
vice which lights the burners. It also has an induced draft
blower to exhaust combustion products.
Keep the blower access doors in place except for in-
spection and maintenance. An interlock switch prevents
furnace operation if the blower door is not in place.
On new installations, or if a functional part such as the
gas valve, pressure switch, or limit control has been
replaced, the operation of the furnace should be checked.
Check furnace operation as outlined in the following
instructions. If any sparking, odors, or unusual noises
are encountered, shut off electrical power and recheck
for wiring errors, or obstructions in or near the blower
motors. Various shipping materials must be removed
before the blower motor is operated.
Heat Anticipator Setting
The heat anticipator in the room thermostat must be
correctly adjusted to obtain the proper number of heat-
ing cycles per hour and to prevent the room thermostat
from over-shooting the room thermostat setting. Heat
anticipator must be set at 0.7 amps.
Rollout Protection Device
If the flames from the burners are not properly drawn
into the heat exchanger, a protection device will open
causing the gas valve to close. The protection device is
located on the manifold assembly (Figure 25) on GUC
and GUX models and on the burner bracket on GUD
models (Figure 26). This device resets manually.
Flame Roll-Out
Protection
Device
Figure 25
Roll-Out Protection Device - Except GUD
Flame Roll-Out
Protection Device
Figure 26
Roll-Out Protection Device - GUD
CAUTION
The cause must be investigated by a
qualified servicer before any attempt is
made to engage the roll-out protection
device and turn the furnace back on.
Electronic Control Module
This furnace is equipped with a self-diagnosing elec-
tronic control module. In the event a furnace compo-
nent is not operating properly, the control module will
repeatedly flash a red light on and off in a factory-
programmed sequence, depending on the problem en-
countered.
If you suspect the furnace is not operating properly, look
through the observation window in the blower access
door and make note of the number of flashes in the
sequence. Then see Section IX for further information.
Reset After Control Lock-Out
If ignition has not been achieved for any reason after
three ignition cycles, the electronic control module will
lock-out the furnace. A lock-out causes the air blower to
run continuously, and ignition is no longer attempted.
The controls diagnostic light will then repeatedly flash
once and then pause. When this occurs, it may be
necessary to reset the control by turning the thermostat
setting below room temperature for thirty seconds and
then returning the setting to the desired temperature.
The control may also be reset after a lock-out by turning
off the electrical disconnect switch to the furnace for
thirty seconds. The control will automatically reset after
one hour.
IMPORTANT:
If you have to frequently reset your fur-
nace, it means that a problem exists that should be
corrected. Contact a qualified servicer for further infor-
mation.