Carbon monoxide (CO) clues you can see:

• Rusting or water streaking on vent/chimney
• Loose or missing furnace panel
• Sooting
• Loose or disconnected vent/chimney connections
• Debris or soot falling from chimney, fireplace or appliance
• Loose masonry on chimney
• Moisture inside of windows

Carbon monoxide (CO) clues you cannot see:

• Internal appliance damage or malfunctioning components
• Improper burner adjustment
• Hidden blockage or damage in chimneys
  

Only a trained service technician can detect hidden problems and correct these conditions!