Combustion is fuel + oxygen + ignition producing heat and flue gases. Safe combustion requires correct air/fuel ratio, proper venting, and intact heat exchangers. Poor combustion can produce carbon monoxide (CO), a life safety hazard.   Key terms: • Complete combustion: mostly CO2 + H2O (plus nitrogen, excess O2) • Incomplete combustion: CO + soot (often from insufficient oxygen or poor mixing) • Draft/venting: moves flue gases out • Spillage/backdrafting: flue gases enter occupied space • Heat exchanger integrity: prevents flue gas mixing with supply air Worked example (concept): If... Show more

Combustion is fuel + oxygen + ignition producing heat and flue gases. Safe combustion requires correct air/fuel ratio, proper venting, and intact heat exchangers. Poor combustion can produce carbon monoxide (CO), a life safety hazard.
 

Key terms:
• Complete combustion: mostly CO2 + H2O (plus nitrogen, excess O2)
• Incomplete combustion: CO + soot (often from insufficient oxygen or poor mixing)
• Draft/venting: moves flue gases out
• Spillage/backdrafting: flue gases enter occupied space
• Heat exchanger integrity: prevents flue gas mixing with supply air

Worked example (concept):
If a furnace has blocked venting, flue gases may spill at the draft hood. CO risk increases. Proper response: shut down, ventilate, test, correct venting before operation.

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