27
LIGHTING INSTRUCTIONS
This appliance is equipped with either a
direct spark ignition device or a hot
surface silicon carbide 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
CONTROL 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 control 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 control door.
10. Turn on all electric power to the
appliance.
11. Set the thermostat to desired setting.
12. 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. Remove control door.
4. Move switch to the "OFF" position.
5. 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 &
INVESYS CLIMATE CONTROLS
Integrated Controls with Hot
Surface Ignition.
1. Each time the thermostat “W”
(Heating) contacts close, the
induced draft blower (inducer)
begins a prepurge cycle.
2. The air proving negative pressure
switch(es) closes.
3.
5 seconds after the pressure
switch(es) close, the hot surface
igniter begins heating for 30
seconds
to full temperature. The
induced draft blower operates for
the complete heating cycle.
4. After the 30-second igniter warm
up,
the gas valve opens for an
8-second trial for ignition.
5. The igniter lights the gas burners
and
stays energized for the first
7 seconds after the gas valve
opens.
6. 8 seconds after the gas valve
opens
the remote 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
approximately 20 seconds after the
burners ignite.
8. When the thermostat “W” (Heat
Call) 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 35 seconds to
prepurge.
2. 5 seconds into prepurge, the hot
surface igniter heats for 30
seconds. The inducer continues to
run.
3. After the 30-second igniter warm
up, 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 during the
8th second after the gas valve
opens, the gas valve closes, and
the igniter de-energizes.
5. After 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 30-second pre-purge, the
igniter energizes and begins a 30-
second warm-up period (inducer is
still running). After a 30-second
igniter warm-up period (60 sec. of
ind. running), the gas valve opens
and the control looks for a flame
signal for up to 8 seconds. If no
flame is sensed, the control goes
into “self-healing” mode, in which
the blower and inducer both run for
three minutes before another
ignition attempt is made.
NOTE: The following applies only
to units manufactured before
third Quarter 2003:
After 5-second
inter-purge, the control begins a
30-second pre-purge followed by a
30-second igniter warm-up period
(inducer is still running). After the
30-second igniter warm-up period,
the gas valve opens and the
control looks for a flame signal for
up to 8 seconds. If no flame is
sensed, the control goes into “self-
healing” mode, in which the blower
and inducer both run for three
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.
Note that second and fourth
ignition attempts will have a 30-
second pre-purge followed by a 30-
second igniter warm-up period.
This prevents the igniter from
overheating.
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.
UT Electronic Controls Direct Spark
Ignition
WARNING
!
START-UP PROCEDURE
