5-571.4
20
20
service & troublesHooting
Pilot does not light
main burners do not light (Pilot is lit)
lifting flames (see figure 21.1)
yellow tipping
(With propane gas, some yellow tipping
is always present.)
flashback
floating flames (see figure 21.2)
1. Main gas is off.
2. Power supply is off.
3. Air in gas line.
4. Dirt in pilot orifice.
5. Gas pressure out of proper range.
6. Pilot valve does not open.
a. Defective ignition controller.
b. Defective gas valve.
7. No Spark at ignitor.
a. Loose wire connections.
b. Pilot sensor is grounded.
c. Defective ignition controller.
8. Safety device has cut power.
1. Defective valve.
2. Loose wiring.
3. Defective pilot sensor
4. Defective ignition controller.
5. Improper thermostat wiring.
1. Too much primary air.
2. Main pressure set too high.
3. Orifice too large.
1. Insufficient primary air.
2. Dirty orifice.
3. Misaligned orifice.
1. Too much primary air.
2. Main pressure set too high.
3. Orifice too large.
1. Insufficient primary air.
2. Main pressure set too high.
3. Orifice too large.
4. Blocked vent cap.
1. Open manual gas valve.
2. Turn on main power.
3. Purge gas line.
4. Check for plugged pilot orifice and clean
with compressed air if necessary.
5. Adjust to a maximum of 14" W.C.
Minimum for Natural Gas - 6" W.C.
Minimum for Propane Gas - 11" W.C.
6. Check wiring for 24 volts to valve.
a. Replace ignition controller.
b. Replace gas valve.
7.
a. Check all ignition controller wiring.
b. Replace sensor if cracked or worn
c. Replace ignition controller.
8. Check all safety devices (High limit, air
flow proving switch, power exhauster
centrifugal switch - HFP Models Only,
gas pressure switches, etc.) Determine
and correct problem. Reset if necessary.
1. Replace valve.
2. Check wiring to gas valve.
3. Replace pilot sensor.
4. Replace ignition controller.
5. Verify wiring compared to wiring diagram.
1. Reduce primary air.
2. Adjust to a maximum of 14" W.C.
3. Check orifice size with those listed on the
serial plate.
1. Increase primary air.
2. Check orifices and clean with
compressed air if necessary.
3. Check manifold, replace if necessary.
1. Reduce primary air.
2. Adjust to a maximum of 14" W.C.
3. Check orifice size with those listed on the
serial plate.
1. Increase primary air.
2. Adjust to a maximum of 14" W.C.
3. Check orifice size with those listed on the
serial plate.
4. Clean louvers in vent cap.
trouble
Possible cause
Possible remedy
table 20.1
troubleshooting
IMPORTANT
To check most of the Possible Remedies in the troubleshooting
guide listed in Table 20.1, refer to the applicable sections of the
manual.
cAUTION
Do not reuse any mechanical or electrical component which
has been wet. Such component must be replaced.
WARNING
When servicing or repairing this equipment, use only factory-
approved service replacement parts. A complete replacement
parts list may be obtained by contacting Modine Manufacturing
Company. Refer to the rating plate on the appliance for
complete appliance model number, serial number, and
company address. Any substitution of parts or controls not
approved by the factory will be at the owner’s risk.
