30
LIGHTING INSTRUCTIONS
This appliance is equipped with a direct
spark ignition device. This device lights
the main burners each time the room
thermostat (closes) calls for heat. See
lighting instructions on the furnace.
TO START FURNACE
1.
BE SURE THAT THE MANUAL GAS
VALVE HAS BEEN IN THE “OFF”
POSITION FOR AT LEAST FIVE
MINUTES. DO NOT ATTEMPT TO
MANUALLY LIGHT THE MAIN
BURNERS. FAILURE TO FOLLOW
THIS WARNING CAN CAUSE A FIRE
OR AN EXPLOSION RESULTING IN
PROPERTY DAMAGE, PERSONAL
INJURY OR DEATH.
2. Set the thermostat to lowest setting.
3. Turn off all electric power to the
appliance.
4. This appliance does not have a pilot.
It is equipped with an ignition device
which automatically lights the burner.
Do NOT try to light the burner by hand.
5. Remove burner compartment door.
6. Move switch to the "OFF" position.
NOTE: Use only your hand to move
the gas control switch. Never use
tools. If the switch will not move by
hand, don't try to repair it; call a
qualified service technician. Force
or attempted repair may result in a
fire or explosion.
7. Wait five (5) minutes to clear out any
gas. Then smell for gas, including
near the floor. If you smell gas, STOP!
Follow the safety instructions on the
front page of this manual. If you don't
smell gas, go to the next step.
8. Move switch from "OFF" position to
"ON" position.
9. Replace burner compartment door.
10. Turn on all electric power to the
appliance.
11. Turn manual gas valve to the “ON”
position.
12. Set the thermostat to desired setting.
13. If the appliance will not operate, follow
the instructions below to shut down
furnace and call your service
technician or gas supplier.
TO TURN OFF GAS TO FURNACE
1. Set the thermostat to the lowest setting.
2. Turn off all electric power to the
appliance if service is to be performed.
3. Turn manual gas valve to the “OFF”
position.
4. Remove control door.
5. Move switch to the "OFF" position.
6. Replace control door.
WARNING
!
SHOULD OVERHEATING OCCUR OR
THE GAS SUPPLY FAIL TO SHUT
OFF, SHUT OFF THE MANUAL GAS
VALVE TO THE APPLIANCE BEFORE
SHUTTING OFF THE ELECTRICAL
SUPPLY. FAILURE TO DO SO CAN
CAUSE AN EXPLOSION OR FIRE
RESULTING IN PROPERTY DAMAGE,
PERSONAL INJURY OR DEATH.
SEQUENCE OF OPERATION
UT Electronic Controls Direct Spark
Ignition
1. Each time the thermostat contacts
close, the induced draft blower
(inducer) begins a prepurge cycle.
2. The air proving negative pressure
switch(es) closes.
3.
30 seconds after the pressure
switch(es) close, the spark igniter
energizes.
The induced draft
blower operates for the complete
heating cycle.
4. After the spark igniter energizes,
t
he gas valve opens for a 8 second
trial for ignition.
5. The igniter lights the gas burners.
6. After the gas valve opens t
he flame
sensor must prove flame ignition
for one second
using the process
of flame rectification. If the burners
don’t light, the system goes
through another ignition sequence.
It does this
up to four
times.
7. The main blower starts 20 seconds
after the burners ignite.
8. When the thermostat cycle ends,
the gas valve closes, the burners
go out, the induced draft blower
stops after a
10-second post-
purge,
and the negative pressure
switch(es) open.
9. The main blower continues until
timed off by the setting on the
integrated furnace control board.
Sequence if the system doesn’t light or
doesn’t sense flame:
1. On a call for heat, the control runs
the inducer for 30 seconds to pre-
purge.
2. After the 30-second pre-purge, the
spark igniter energizes. The
inducer continues to run.
3. After the spark igniter energizes,
the gas valve opens for an 8-
second trial for ignition. The
inducer continues and the igniter
stays energized.
4. If flame is not sensed within 8
seconds after the gas valve opens,
the gas valve closes, the igniter de-
energizes and:
5. The inducer completes a 10-
second post-purge, the inducer
stops, and the control verifies that
the pressure switch has opened.
Once the open pressure switch is
confirmed, the control begins the
next ignition cycle by energizing
the inducer for a pre-purge of 30
seconds. After the pre-purge, the
igniter energizes and the gas valve
opens (inducer continues to run). If
no flame is sensed on the second
attempt, the control goes into a
“self-healing” mode, in which the
blower and the inducer run for 3
minutes before another ignition
attempt is made.
6. The control attempts to ignite up to
four times (first attempt followed by
three retries). After the fourth
failure to ignite, the control goes
into a one-hour “soft-lockout”
during which the control will not
respond to the thermostat heat call
(W). The lockout can be reset by
shutting off main power to the
furnace for five seconds, or by
turning the heat call (W) from the
thermostat off and then back on.
7. The above sequence will repeat
after a one hour delay. It will
continue repeating until ignition is
successful or the call for heat is
terminated.
8. To reset the lock out, make and
break power either at the
thermostat or at the unit disconnect
switch for 5 to 10 seconds. It then
goes through another set of trials
for ignition.
WARNING
!
START-UP PROCEDURE
Summary of Contents for GMDA
Page 40: ...40 CM 0810...
