IO137 14
This furnace uses a vent pressure switch that prevents the furnace from operating should any por-
tion of the vent system become restricted or a venter failure occur. To check this switch, place the
furnace in operation and remove the hose from the switch. The gas burners will extinguish. Re-
placing the hose will allow the furnace to operate normally.
FLAME ROLL-OUT SWITCH
This furnace is equipped with a flame roll-out switch(s). This manually resetable switch is a 1/2”
disc type and is non-adjustable. This switch is designed to shut down the burner gas if there are
flames outside the heat exchanger. Should this switch function, contact a qualified service person
to determine the cause of function before resetting. To reset this switch press the button on top of
the switch after the furnace has cooled. To test the operation of the switch with the furnace in op-
eration, place an open flame on the disc portion of the switch. The switch should function to shut
down the burner gas. Wait until the furnace has cooled sufficiently before resetting the
switch.
FLAME SENSOR
The ignition is provided by an electronic ignition system. The burner flames will become extin-
guished if the flame sensor fails to detect the presence of the burner flame. To test, disconnect the
flame sensor wire before placing the furnace in operation. The electronic ignition device should
attempt to light the burners. However, the burners should shut off after a few seconds of opera-
tion. Disconnect the electrical supply to the furnace, reinstall the disconnected sensor wire and
reset the power supply to restore the furnace to its normal operation.
BLOWER DOOR INTERLOCK SWITCH
The purpose of the switch is to disconnect electrical power to the furnace should the blower door
become dislodged, removed, or not properly reinstalled. ALLOWING THE FURNACE TO
OPERATE WITHOUT THE BLOWER DOOR BEING SECURELY IN PLACE CAN CAUSE
COMBUSTION PRODUCTS TO BECOME CIRCULATED THROUGHOUT THE LIVING AREA
WHICH CAN CAUSE SERIOUS ILLNESS OR CARBON MONOXIDE POISONING. To test the
operation of this switch, place the furnace in operation and remove the blower access door. The
burner flames will extinguish and the venter and circulating air blowers should both stop. To re-
store the unit to normal operation, shut off the electrical power to the unit, replace the blower ac-
cess door and restore the electrical power.
INTEGRATED FAN / IGNITION CONTROL
This furnace is equipped with a combination ignition module and fan control. The ignition source is
an electronic device. This device ignites the burners upon a call for heat. It also controls the venter
blower and the various speed selections and timings of the circulating air blower. This control is
located in the circulating air blower compartment. Upon a demand for heat the venter is energized.
After a short purge, the electronic ignition device is energized. The burners are ignited and after a
short delay, the burner flame is proven. The circulating air blower is energized approximately thirty
(30) seconds after the burners are ignited. The circulating air blower is de-energized by a field se-
lectable fan off timer. THIS CONTROL IS NOT FIELD SERVICABLE.
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