Internal Wiring; Thermostat; Furnace Section Controls And Ignition System; Normal Furnace Operating Sequence - Trane Oxbox 14 Seer Series Installation Instructions Manual

UNIT CONTROL BOX

THERMOSTAT

THERMINAL STRIP
R R
G G
Y Y
W W
C
C
Fig. 5-1 Typical Field Control Wiring Diagram
CONTACTOR
GROUND
LUG
Refer to electrical data tables
to size the disconnect
Fig. 6-2 Typical Field Power Wiring Diagram

5.3 INTERNAL WIRING

IMPORTANT: Some single phase units are equipped with a single
pole contactor. Caution must be exercised when servicing as only one
leg of the power supply is broken with the contactor.
Some models are equipped with an electronically commutated blower
motor which is constantly energized unless the main unit disconnect
is in the off position.
A diagram of the internal wiring of this unit is located under the
electrical box cover and in this manual. If any of the original wire as
supplied with the appliance must be replaced, the wire gauge and
insulation must be the same as the original wiring.
Transformer is factory wired for 230 volt on 208/230 volt models and
must be changed to 208 volt applications. See unit wiring diagram for
208 volt wiring.
5.4 THERMOSTAT
The room thermostat must be specifically designed to control
package gas electric units.
6.0 FURNACE SECTION CONTROLS AND
IGNITION SYSTEM

6.1 NORMAL FURNACE OPERATING SEQUENCE

This unit is equipped with an integrated direct spark ignition control.
1. The thermostat calls for gas heat.
2. The control board will run a self check to verify that the limit control
and manual reset overtemperature control are closed and that the
pressure switch is open. If so, the induced draft blower (inducer)
begin a prepurge cycle.
3. The air proving negative pressure switch closes.
1
Field-supplied disconnect
Single
p h a s e
p o w e r
supply
4. 15 seconds after the pressure switch closes, the gas valve opens
and the spark is initiated for a 7 second trial for ignition.
5. Burners ignite and flame sensor proves all burners have lit.
6. The circulating air blower is energized after 45 seconds.
240V
7. The control board enters a normal operation loop in which all safety
208V
controls are monitored continuously.
8. Thermostat is satisfied and opens.
9. The gas valve is de-energized and closes, shutting down the burner
flame.
10.The control board will de-energized the inducer after a five second
post purge.
11.The circulating air blower BLOWER-LOW is de-energized after
COM
max. 90 seconds.
· The integrated control board has a three times ignition system.
· After a total of 3 trials for ignition without sensing main burner flame,
the system goes into lockout mode.
· After 1 hour, the ignition control repeats the prepurge and ignition
cycles for 3 tries and then goes into lockout mode again.
· It continues this sequence of cycles and lockout each hour until
ignition is successful or power is interupted.
· During the lockout mode, neither the spark ignition control or gas
valve will be energized until the system is reset by turning the
thermostat to the "OFF" position or interrupting the electrical power
to the unit for 3 seconds or longer.
· The induced draft blower and main burner will shut off when the
thermostat is satisfied.
· The circulating air blower will start and run on the heating speed if
the thermostat fan switch is in the "ON" position.
The integrated furnace control is equipped with diagnostic LED. The
LED is lit continuously when there is power to the control without a call
for heat. If the LED is not lit, there is either no power to the control or
there is an internal component failure within the control, and the
control should be replaced.
If the control detects the following failures, the LED will flash for
designated failure detections.
2 Flash: Failed to detect or sustain flame,system locked out.
3 Flash: Pressure switch or induced draft blower problem detected.
4 Flash: High limit or auxiliary limit open.
5 Flash: Flame sensed and gas valve not energized or flame sensed
with no "W" signal.
6 Flash: Overtemperature switch open.
7 Flash: Thermostat miswired; W1 and W2 swapped.
Slow flash rate:Normal,call for heat.

6.2 OPERATING INSTRUCTIONS

This appliance is equipped with a direct spark intermittent ignition
device. This device lights the main burners each time the room
thermostat (closes) calls for gas heat. See operating instructions on
the back of the furnace/controls access panel.
Do not attempt to manually light this furnace with a match or any
open flame. Attempting to do so can cause an explosion or fire
resulting in property damage, personal injury or death.

6.3 TO START THE FURNACE

1. Set the thermostat to its lowest setting.
2. Turn off all electric power to the appliance.
3. 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.
4. Remove control door.
5. Turn the gas valve to the "OFF" position.
6. Wait five (5) minutes to clear out any gas. Then smell for gas,
including near the floor. If you smell gas, STOP! Follow B in the
safety information on the Operating Instructions located on the
back of the controls/access panel. If you don't smell gas, go to the
next step.
7. Turn the gas valve to the "ON" position.
8. Replace the control door.
9. Turn on all electric power to the appliance.
10. Set the thermostat to the desired setting.
11. If the appliance will not operate, follow the instructions below to
shut down the furnace.
WARNING
installation & owner's manual
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