Submittal Sheet

7800 SERIES S7800A2142 KEYBOARD DISPLAY MODULE
32-00110—05 20
Fault 16
*Flame-Out Timer*
No-flame detected during
Pilot Flame Establishing
Period.
1. Measure the flame signal. If one exists, make sure it meets
specifications. Make any necessary burner adjustments
using manufacturer instructions.
2. Make sure that the flame amplifier and flame detector are
compatible.
3. If the code reappears, replace the amplifier and/or the
flame detector.
4. If the fault persists, replace the relay module.
Fault 17
*Main Flame Fail*
Main flame failure during
RUN after flame is
established an on for at least
10 seconds.
1. Inspect the main fuel valve(s) and connection(s).
2. Make sure that the fuel pressure is high enough to supply
fuel to the combustion chamber.
3. Check the flame detector sighting for adequate flame sig-
nal throughout the burner firing rate.
Fault 18
*Flame Detected*
Flame sensed when the
shutter is open and no flame
is expected during
PREPURGE.
1. Check that flame is not present in the combustion cham-
ber. Correct any errors.
2. Make sure that the flame amplifier and flame detector are
compatible.
3. Check the wiring and correct any errors. Make sure F and G
wires are in individual conduits and protected from stray
noise pickup.
4. Remove the flame amplifier and inspect the connectors.
Reset the flame amplifier.
5. Reset and sequence the relay module.
6. If the code reappears, replace the flame amplifier and/or
the flame detector.
7. If the fault persists, replace the relay module.
Fault 19
*Main Flame Ign.*
Flame was lost during MFEP
or the first 10 seconds of the
RUN state.
1. Inspect the main fuel valve(s) and connection(s).
2. Make sure the fuel pressure is high enough to supply fuel
to the combustion chamber.
3. Make sure the flame detector is positioned to obtain the
required flame signal strength; reset and recycle.
Fault 20
*Low Fire Sw. Off*
Low Fire Interlock switch
failure to close during
PREPURGE.
1. Check wiring and correct any errors.
2. Reset and sequence the relay module.
3. Use either the manual motor potentiometer to drive the
motor to the Low Fire position or use the Run/Test Switch
option, if available. Sequence to Prepurge drive to Low Fire
and place in the Test Position. Adjust the Low Fire Switch to
make sure it closed properly.
4. Measure the voltage between terminal 18 and L2(N) while
in the Prepurge drive to Low Fire state. Line supply voltage
should be present. If not, the switch adjustment is incorrect
and/or the switch is defective and needs replacing.
5. Reset and sequence the relay module. If line supply voltage
was present between the Low Fire Switch and terminal 18,
and the fault still persists, replace the relay module.
Fault 21
*Running ILK*
Running Interlock fault
during PREPURGE.
1.
Check wiring and correct any errors.
2. Inspect the fan; make sure there is no blockage of the air
intake and that it is supplying air.
3. Make sure the Interlock Switches are working properly and
that all switch contacts are free of contaminants.
4. Reset and sequence the relay module to PREPURGE (place
the Run/Test Switch in the Test position, if available). Mea-
sure the voltage between terminals 7 and L2(N). Line volt-
age should be present.
5. If steps 1 through 4 are correct and the fault persists,
replace the relay module.
Fault 22
*Lockout ILK*
Lockout Interlock fault during
PREPURGE.
Fault 23
*Airflow Switch*
Combustion airflow interlock
fault during PREPURGE.
Fault 24
*Call Service*
The flame interlock (relay
module) was on when it
should be off.
1. Check for F leadwire routing. Make sure routing is in its
conduit and isolated from noise-producing circuits.
Fault 25
*Call Service*
The flame interlock (relay
module) was off when it
should be on.
Table 5. Fault Message Summary. (Continued)
Fault Code System Failure Recommended Troubleshooting