The products of which process are exhausted by an induced-draft blower in many HVAC systems?

• A. Condensation
• B. Ventilation
• C. Combustion
• D. Evaporation

Answer: (C)

Induced-draft blowers are used to remove the gases produced when fuel is burned in the furnace or boiler. The combustion process creates hot, buoyant exhaust that must be vented outdoors to prevent buildup and to keep the system safe and efficient. By pulling these combustion byproducts through the vent stack, the blower carries out the products of combustion—primarily carbon dioxide and water vapor, along with any trace gases—out of the building. The other options aren’t what the blower is designed to exhaust: condensation is moisture that can form in some systems, ventilation refers to general air exchange, and evaporation is a phase change, not the specific exhaust function of the device.