Troubleshooting; No Error Code Displayed - Burnham CHG CHG225 Installation & Operation Manual

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A. Troubleshooting problems where no error code is displayed:
Table 13.1: No Error Code 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
xIV Troubleshooting
warNINg
• 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
Figure 13.2: MBCa Fuse Location
POSSIBLE CAUSES
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