Troubleshooting; No Error Code Displayed; Mbca Fuse Location - Crown Boiler BWC Series Installation Instructions Manual

TURN OFF POWER TO BOILER BEFORE REPLACING FUSES OR WORKING ON WIRING.
A. Troubleshooting problems where no error code is displayed:
CONDITION
Display Blank, Fan off, LWCO lights off
Display Panel Blank, Fan running
Display reads "U.125" continuously, Fan running
Boiler not responding to call for heat, Status code on display
="0" (see Figure 11.1)
Boiler fires, but display panel is blank
XIII. Troubleshooting
WARNING
Table 13.1: No Error Code Displayed
Figure 13.2: MBCA Fuse Location
50
POSSIBLE CAUSES
• No 120VAC Power at boiler. Check breaker and wiring
between breaker panel and boiler
• Loose 120VAC connection wiring between boiler J-Box and
MCBA
• Blown "F1" fuse in MCBA (see Figure 13.2 for location).
Replace with 5A fuse provided
• Defective AT250 transformer
• Blown "F3" fuse in MCBA (see Figure 13.2 for location).
Replace with 4A slow-blow fuse provided
• Boiler is not seeing call for heat. Check thermostat or
zone wiring for loose connection, miswiring, or defective
thermostat/zone control.
• Loose ribbon cable
• Defective display