TROUBLESHOOTING IGNITION SYSTEM
Fault Messages and Lockout Status (* = stage number: 1, 2, 3, or 4)
Fault Displayed | Description | Red LED | Lockout | |
“Display Fail” | Communications with UIM interrupted | Continuous | Auto Reset |
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| Check communication cable to UIM. Try moving to other Internal Communications connector on MCB. Also check the | |||
| connectors where the cable is plugged in for best connecting wires. |
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“Comm. Fail Stg.*” | Communications with FCB interrupted | Continuous | Auto Reset | |
| Same as above. Also try swapping FCB and UIM communications cables. |
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“Low AC Voltage” | Line voltage less than 90 vac | Continuous | Auto Reset | |
| Check incoming power line for loss of voltage. May also be caused by a power line | |||
“Low 24VAC” | Voltage from transformer less than 18 vac | Continuous | Auto Reset | |
| Check transformer output. Should be over 24vac. May be caused by excessive current drain or a faulty transformer | |||
“Brown Out Reset” | Indicates a brown out reset occurred | - - - - | None | |
| Caused by a momentary dip in voltage on the MCB +5vdc power bus. Contact factory. (Not considered a serious problem | |||
| if it only occurs on very rare occasions.) |
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“Timeout Reset” | Indicates a watchdog reset occurred | - - - - | None | |
| Caused when the micro executes the software in an improper way. Contact factory. (Not considered a serious problem if it | |||
| only occurs on very rare occasions.) |
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“FCB Comm Timeout” | FCB did not receive command from MCB | Continuous | SOFT | |
| Caused when communications between the MCB and the FCB are interrupted. May occur when a surge of power on a | |||
| nearby device (i.e. arc welder) creates an EMI burst. Not a serious problem if it occurs rarely. |
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“No Flow” | Water is not flowing | Continuous | SOFT | |
| Caused by the flow switch being open when it should be closed. Check water lines, pump, flow switch contacts, wiring. | |||
“Blower Prov Stg* | Blower pressure is too low it they should have been closed. | Continuous | SOFT | |
| Check blower, switch contact, wiring, and for air leaks. |
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“Blocked Flue” | Flue is Blocked | Continuous | SOFT | |
| Caused by the blocked flue switch contacts being open when they should have been closed. Check for flue blockage, switch | |||
| contacts, wiring. |
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“Blocked Inlet” | Air Inlet is blocked |
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| Check inlet terminal, venturi screen and burner tube for debris. If inlet is clear check blocked inlet flue switch for continuity. | |||
| Inspect hose to switch to ensure it is connected and not cracked or spilt. |
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“High Limit” | Outlet temp. exceeded high limit setpoint | Continuous | Auto Reset | |
| Caused when the temperature of the outlet probe exceeds the high limit setpoint. This is an internal “software” limit switch and | |||
| not an actual device. Check that the over temperature is not being caused by improper setup or operation of the boiler. | |||
“MRHL” | Outlet temp is too high | Flashing | HARD | |
| Caused when the MRHL (a thermostat) contacts in the Outlet probe are open when they should be closed. Fault may be due | |||
| to high outlet temperature, bad switch contacts in the probe, or disconnected wiring. Note: The MRHL can be checked by | |||
| disconnecting the outlet probe from the MCB and reading the resistance across the two active pins on the connector at the | |||
| end of the probe cable. The value should be approximately 0 ohms when the temperature of the probe is less than 220°F. | |||
“Low Water” | Water level is too low | Flashing | HARD | |
| Caused by the Low Water Cut Out device not closing its feedback switch contacts when it should. Check water line, switch | |||
| contacts, wiring, LWCO. |
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“Low Gas” | Gas pressure is too low | Flashing | HARD | |
| Caused by the Low Gas switch being open when it should be closed. Check gas line, switch contacts, wiring. | |||
“Powered Accessory” | Power vent not running | Flashing | HARD | |
| Caused by the Powered Vent device not closing its feedback switch contacts when it should. Could also be caused by a | |||
| problem with the relay output on the MCB. Check output to powered vent, switch contacts, wiring. |
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“High Gas Stg*” | Gas pressure too high | Flashing | HARD | |
| Caused by the High Gas switch being open when it should be closed. Check gas line, switch contacts, wiring. | |||
“Inlet Probe” | Inlet probe shorted or open | Flashing | HARD | |
| Caused when the thermistor in the probe or the wiring to the probe is shorted or disconnected. Check the probe. Note: The | |||
| thermistor and wiring can be checked by disconnecting the probe from the MCB and reading the resistance across the two | |||
| active pins on the connector at the end of the probe cable. The value should be approximately 10K ohms (value will change | |||
| slightly with changes in temperature). |
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“Outlet Probe:” | Outlet probe shorted or open | Flashing | HARD | |
| Caused when the thermistor in the probe or the wiring is shorted or disconnected. Check the probe. Note: the thermistor and | |||
| wiring can be checked by disconnecting the probe from the MCB and reading the resistance across the two active pins on | |||
| the connector at the end of the probe cable. The value should be approximately 10K ohms (value will change slightly with | |||
| changes in temperature). |
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“Tank Probe” | Tank (Remote) probe shorted or open | Flashing | HARD | |
| Caused when the thermistor in the probe or the wiring is shorted or disconnected. Check the probe. Note: the thermistor and | |||
| wiring can be checked by disconnecting the probe from the MCB and reading the resistance across the two active pins on | |||
| the connector at the end of the probe cable. The value should be approximately 10K ohms (value will change slightly with | |||
| changes in temperature). |
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“Igniter Stg*” | Igniter current is too low | Flashing | HARD | |
| Caused by a low current draw problem with the igniter. This may occur if the igniter is old, damaged, or disconnected and | |||
| no longer draws the proper level of current. This condition will affect the ability of the igniterto get hot enough to fire the gas | |||
| properly. Check the igniter and its associated wiring. |
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“Igniter Pwr Stg*” | Improper power applied to the igniter circuit | Flashing | HARD | |
| Caused by improper line power being applied to the igniter circuitry. Check line connections. Paying particular attention to | |||
| the earth ground connection. Also check that line voltage does not exceed 132 VAC RMS. |
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“Igniter Hdwr Stg*” | Hardware problems with igniter circuit | Flashing | HARD | |
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