Lighting And Shutdown Instructions; Ignition System Checks - Space-Ray LTU SERIES Installation And Operation Instructions Manual

20.0)

LIGHTING AND SHUTDOWN INSTRUCTIONS

1) Turn on the gas supply.
2) Set the thermostat to call for heat.
3) Ignition should occur after the 30-second air purge.
4) If ignition fails, the unit will spark for approximately 21 seconds and go into safety lockout. Turn the thermostat (power)
off for 60 seconds to take the system out of lockout.
5) If the heater does not light, shut off gas completely for 5 minutes before attempting to relight.
6) CAUTION: The heater must be grounded. Poor grounding will give nuisance lockouts, particularly during momentary
power interruptions.
7) To shut down the heater, turn off the gas and the electrical supply.
NOTE:
The Lighting and Shutdown Instructions are also shown on the permanent nameplate attached to the heater control box.
21.0)

IGNITION SYSTEM CHECKS

STEP 1: CHECK IGNITION CABLE.
a) Make sure that the ignition cable does not touch any metal surface.
b) Make sure that connections to the stud terminal and the igniter/sensor are clean and tight.
c) Make sure that the ignition cable provides good electrical continuity.
STEP 2: CHECK IGNITION SYSTEM GROUNDING.
(Nuisance shutdowns are often caused by a poor or erratic ground.) A common ground is required for the module, igniter,
flame sensor and main burner.
a) Check for good metal-to-metal contact between the igniter bracket and the main burner.
b) Check the ground lead from the GND (BURNER) terminal on the
module to the igniter bracket. Make sure connections are clean and
tight. If the wire is damaged or deteriorated, replace it.
c) Replace igniter/sensor with factory replacement part if insulator is
cracked.
STEP 3: CHECK SPARK IGNITION CIRCUIT.
WARNING: THE IGNITION CIRCUIT GENERATES A 20,000 VOLT
OPEN CIRCUIT AND ELECTRICAL SHOCK CAN RESULT.
a) Check ignition cable.
b) Check external fuse on the module.
c) Verify power (24V) at module input terminals and output terminal to
gas valve.
d) Replace spark module if fuse and power are OK.
STEP 4: CHECK FLAME SENSOR CIRCUIT.
a) Turn off heater at thermostat.
b) Connect a meter (dc microammeter scale) in series with the ground lead as shown in the diagram. Use a Honeywell
W136 Test Meter or equivalent. Connect the meter as follows:
Disconnect the ground lead at the electronic control.
Connect the black (negative) meter lead to the electronic control GND terminal.
Connect the red (positive) meter lead to the free end of the ground lead.
c) Restart the system and read the meter. The flame sensor current must be steady and measure at least 1.5 micro amps.
d) If the meter reads less than the minimum or if reading is unsteady:
Make sure burner flame is capable of providing a good rectification signal.
Make sure fasteners securing igniter/sensor are tightened to assure correct positions. DO NOT relocate
igniter/sensor.
Check for excessive (over 1000ºF) temperature at ceramic insulator on flame sensor. Excessive temperature can
cause short to ground. DO NOT relocate igniter/sensor.
Check for cracked ceramic insulator, which can cause short to ground, and replace sensor if necessary.
Make sure that electrical connections are clean and tight. Replace damaged wire
e) Remove microammeter and reconnect ground wire. Return system to normal operation.
–38–
Form #43155260
Mar–05