Boiler Safety Limit Open
Boiler Safety Limit wired to terminals J6-1, 2 or 3 OPEN:
• Condensate Trap Float Switch contact open.
• Thermal Link Switch contact open.
• Burner Door Thermostat with manual reset contact open.
• Air Pressure Switch contact open.
• Auto Reset High Limit contact open.
• 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.
• Plugged Condensate Trap - also check to ensure boiler is level.
• Thermal Link Switch blown due to temperature rise above 604°F. (318°C)
• Burner Door Thermostat with manual reset contact open due to temperature rise above 500°F (260°C) - check the cause of overheating (burner door insulation, loose mounting, etc.).
• Air Pressure Switch contact open - check for blocked vent.
• See possible causes for “Hard Lockout 4”.
NOTE
Block Vent Special Note Before a call for heat the air pressure switch is closed. When there is a call for heat with a blocked vent the air pressure switch will open (due to excessive pressure of the blower against a blocked flue pipe) after the blower starts. The control stops the start sequence and stops the blower. After the blower stops the pressure switch re-closes and the cycle continues. The displays shows the cause of trip for only the time the pressure switch is open
