507330-01B
Issue 1809
Page 25 of 33
BEFORE LIGHTING
smell all around the appliance area
for gas. Be sure to smell next to the floor because some
gas is heavier than air and will settle on the floor.
The gas valve on this unit will be equipped with a gas
control switch. Use only your hand to move the switch.
Never use tools. If the switch will not turn or if the control
switch will not move by hand, do not try to repair it.
Placing the Furnace into Operation
These units are equipped with an automatic ignition
system. Do not attempt to manually light burners on these
furnaces. Each time the thermostat calls for heat, the
burners will automatically light. The ignitor does not get hot
when there is no call for heat on units with an automatic
ignition system.
If you do not follow these instructions exactly, a fire
or explosion may result causing property damage,
personal injury or death.
WARNING
Gas Valve Operation
1.
STOP!
Read the safety information at the beginning
of this section.
2. Set the thermostat to the lowest setting.
3. Turn off all electrical power to the unit.
4. This furnace is equipped with an ignition device which
automatically lights the burners. Do not try to light the
burners by hand.
5. Remove the upper access panel.
6. Move switch on gas valve to OFF. Do not force. See
7. Wait five minutes to clear out any gas. If you then
smell gas,
STOP!
Immediately call your gas supplier
from a neighbor’s phone. Follow the gas supplier’s
instructions. If you do not smell gas go to next step.
Figure 34.
Gas Valve Shown in
“ON”
Position
8. Move switch on gas valve to ON. Do not force. See
9. Replace the upper access panel.
10. Turn on all electrical power to the unit.
11. Set the thermostat to desired setting.
NOTE:
When unit is initially started, steps 1 through
11 may need to be repeated to purge air from gas line.
12. If the appliance will not operate, follow the instructions
“Turning Off Gas to Unit” and call your service
technician or gas supplier.
Turning Off Gas to Unit
1. Set the thermostat to the lowest setting.
2. Turn OFF all electrical power to the unit if service is to
be performed.
3. Remove the upper access panel.
4. Move switch on gas valve to OFF. Do not force.
5. Replace the upper access panel.
Failure to Operate
If the unit fails to operate, check the following:
1. Is the thermostat calling for heat?
2. Are access panels securely in place?
3. Is the main disconnect switch closed?
4. Is there a blown fuse or tripped circuit breaker?
5. Is the filter dirty or plugged? Dirty or plugged filters will
cause the limit control to shut the unit off.
6. Is gas turned on at the meter?
7. Is the manual main shut-off valve open?
8. Is the internal manual shut-off valve open?
9. Is the unit ignition system in lock out? If the unit locks
out again, call the service technician to inspect the unit
for blockages.
10. Is pressure switch closed? Obstructed flue will cause
unit to shut off at pressure switch. Check flue and
outlet for blockages.
11. Are flame rollout switches tripped? If flame rollout
switches are tripped, call the service technician for
inspection.
Heating Sequence of Operation
1. When thermostat calls for heat, combustion air blower
starts.
2. Combustion air pressure switch proves blower
operation. Switch is factory set and requires no
adjustment.
3. After a 15 second pre-purge, the hot surface ignitor
energizes.
4. After a 20 second ignitor warm-up period, the gas
valve solenoid opens. A 4 second trial for ignition
period begins.
