Combustion & Air Supply
Combustion principles, primary and secondary air, combustion air requirements for confined spaces, and air supply calculations.
- Explain the three types of combustion air and their roles
- Calculate combustion air requirements for confined spaces
- Identify overfiring and underfiring conditions
Lección 1
Combustion Principles & Air Types
The Fire Triangle
Combustion requires three elements: fuel, oxygen, and ignition. For gas appliances, the fuel is natural gas or propane, oxygen comes from the surrounding air, and ignition is provided by the pilot or electronic igniter.
Three Types of Combustion Air
Primary Air
Mixed with gas before the burner
Controls flame appearance and temperature
Adjusted by the air shutter on the burner
Secondary Air
Surrounds the flame at the burner
Completes combustion of remaining fuel
Enters through the combustion chamber
Dilution Air
Enters the draft hood or barometric damper
Dilutes flue gases for proper draft
Does not participate in combustion
Proper Combustion Indicators
A properly burning gas flame is:
- Blue with a well-defined inner cone
- Stable without lifting, floating, or yellow tips
- Quiet without roaring, rumbling, or popping
Yellow Flames = Danger
A yellow or orange flame on a gas burner indicates incomplete combustion, which produces carbon monoxide (CO). Causes include insufficient primary air, dirty burners, or wrong orifice size. Yellow flames must be corrected immediately.
Three types of air support gas combustion: primary air (mixed before burner), secondary air (at the burner), and dilution air (at the draft hood). A proper flame is blue with a defined inner cone. Yellow flames indicate incomplete combustion and CO production.