Boiler displays HARD or Hard Lockout; unit will not restart until manually reset and underlying fault persists.

Safety first: A hard lockout indicates a serious safety condition. Turn off power and gas. Do not attempt to bypass or jumper any safety devices.

• Read stored fault history: Many Laars controls allow viewing of the last several fault codes. Use the menu buttons to access history and note the codes leading up to HARD.
• Inspect visible safeties: Check rollout switches, high limit switches, and wiring for signs of overheating, discoloration, or manual reset buttons that have tripped.
• Reset once only: After the boiler has cooled and any obvious issues are corrected, you may reset the hard lockout once to see if it returns immediately. If it does, turn the boiler off and call a technician.

When to call a professional: Hard lockouts almost always require professional diagnosis to ensure safe operation.