XIV. Troubleshooting
WARNING
Turn off power to boiler before replacing fuses or working on wiring.
A.Troubleshooting problems where no error code is displayed:
TABLE 14.1: NO ERROR CODE DISPLAYED
CONDITION | POSSIBLE CAUSES | |
Display Blank, Fan off, LWCO lights off | • No 120VAC Power at boiler. Check breaker and wiring between breaker panel | |
and boiler | ||
| ||
| • Loose 120VAC connection wiring between boiler | |
Display Panel Blank, Fan running | • Blown “F1” fuse in MCBA (see Figure 13.2 for location). Replace with 5A fuse | |
| provided | |
| • Defective AT250 transformer | |
Display reads “U.125” continuously, Fan running | • Blown “F3” fuse in MCBA (see Figure 13.2 for location). Replace with 4A slow- | |
| blow fuse provided | |
Boiler not responding to call for heat, Status code on | • Boiler is not seeing call for heat. Check thermostat or zone wiring for loose | |
display =”0” (see Figure 11.1) | connection, miswiring, or defective thermostat/zone control. | |
Boiler fires, but display panel is blank | • Loose ribbon cable | |
• Defective display | ||
|
Figure 14.2: MBCA Fuse Location
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