What term is used for air deliberately introduced near combustion or exhaust devices to compensate for vapor and gases being consumed or expelled?

• A. Fresh Air
• B. Makeup Air
• C. Infiltration Air
• D. Replacement Air

Answer: (D)

Makeup air is the deliberate supply of outside air brought in to replace air that’s been exhausted or consumed by combustion devices. When an exhaust system or a burner draws air out of a space, it can create negative pressure and reduce the available oxygen for the burner. Introducing makeup air near the appliance or exhaust helps restore the pressure balance, ensures enough oxygen for proper combustion, and prevents problems like backdrafting or incomplete combustion. Fresh air is simply outside air in general, but makeup air specifically refers to the planned introduction of air to compensate for what’s been used or expelled. Infiltration air is unintentional leakage, and while some contexts might use replacement air, the standard term used in this context is makeup air.