Honeywell 7800 Series Product Data page 14

7800 SERIES S7800B DISPLAY MODULE
Table 4. Fault Message and Recommended Troubleshooting (continued) .
Fault Code
Fault 15 Flame sensed when shutter
Flame Detected open and no flame is
expected.
Fault 16 Integrated no-flame time
Flame-Out Timer exceeded the limit during
Pilot Flame Establishing
Period.
Fault 17 Main flame failure during
Main Flame Fail Run after flame has been
established and on for at
least 10 seconds.
Fault 18 Flame sensed when shutter
Flame Detected open and no flame is
expected during Prepurge.
Fault 19 Flame was lost during
Main Flame Ign. MFEP or the first 10
seconds of the Run state.
Fault 20 Low fire interlock switch
Low Fire Sw. Off failure to close during
Prepurge.
65-0219—1
System Failure
1. Check that flame is not present in the combustion chamber; correct
any errors.
2. Assure that the flame amplifier and flame detector are compatible.
3. Check wiring and correct any errors.
4. Remove the flame amplifier and inspect its connectors. Reseat the
flame amplifier.
5. Reset and sequence the 7800.
6. If the code reappears, replace the flame amplifier and/or the flame
detector.
7. If fault persists, replace the relay module.
1. Measure the flame signal. If one exists, does it meet specifications?
Make appropriate burner adjustments.
2. Assure that the flame amplifier and the flame detector are
compatible.
3. Replace the flame amplifier and/or the flame detector if necessary.
4. If the fault persists, replace the relay module.
1. Inspect the main fuel valve(s) and its connection(s).
2. Verify that the fuel pressure is sufficient enough to supply fuel to the
combustion chamber. Inspect the connections to the fuel pressure
switches. Assure that they are functioning properly.
3. Inspect the Airflow Switch and assure that it is functioning properly.
4. Check the flame detector sighting position; reset and cycle.
Measure flame signal strength. Does it meet specifications? If not,
refer to the flame detector and/or flame amplifier checkout
procedures in the installation and instruction sheets.
1. Check that flame is not present in the combustion chamber. Correct
any errors.
2. Assure that the flame amplifier and flame detector are compatible.
3. Check wiring, correct any errors.
4. Remove the flame amplifier and inspect its connectors. Reseat the
flame amplifier.
5. Reset and sequence the 7800.
6. If the code reappears, replace the flame amplifier and/or the flame
detector.
7. If the fault persists, replace the relay module.
1. Inspect the main fuel valve(s) and connections.
2. Verify that the fuel pressure is sufficient to supply fuel to the
combustion chamber. Inspect the connections to the fuel pressure
switches to assure that they are functioning properly.
3. Inspect the Airflow Switch to assure that it is functioning properly.
4. Check the flame detector sighting position; reset and cycle.
Measure flame signal strength. Does it meet specifications? If not
refer to the flame de-tector and/or flame amplifier checkout
procedures in the installation and instruction sheets.
1. Check wiring; correct any errors.
2. Reset and sequence the 7800.
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 while in this state to assure that
it is closing properly.
4. While in the Prepurge drive to Low Fire state, measure the voltage
between terminal 19 and G (ground). 120 Vac should be present. If
not, the switch adjustment is incorrect and/or the switch is defective
and should be replaced.
5. Reset and sequence the 7800. If 120 Vac was pre-sent between the
Low Fire switch and terminal 19 and the fault still persists, replace
the relay module.
Recommended Troubleshooting
14
(continued)