Condition
- Boiler Safety Limit wired to terminals J6-1, 2 or 3 open
- Thermal Fuse Switch contact open.
- Air Pressure Switch contact open.
- Auto Reset High Limit contact open.
More Info: Troubleshoot “Limit String”
Possible Cause
- Loose wiring to limit device.
- Auto Reset Supply high limit sensor detected temperature in excess of 200°F.
- Defective Auto Reset Supply High Limit Switch.
- Thermal Fuse Switch blown due to temperature rise above 358°F.
- Air Pressure Switch contact open – check for blocked vent/air intake.
- See possible causes for “Hard Lockout 4”.
