C-5,6,7

What is the main purpose of a combustion air blower?

• To cool the combustion chamber

• To remove exhaust gases

• To move air through the burners and heat exchanger during heating

• To ignite the burners

What factor is essential when selecting a fan unit for mid-efficient appliances?

• The heat exchanger's material

• The fan's durability under high temperatures and cycling

• The color of the appliance

• The fuel type

What does an induced draft fan specifically help overcome in an appliance?

• Atmospheric pressure

• Heat transfer limitations

• Resistance to airflow in the heat exchanger

• Temperature fluctuation

Static pressure in a fan system is most comparable to:

• Airflow speed

• Sound frequency

• Inflation of a balloon

• Temperature difference

Which appliance type does NOT require a fan to assist in combustion?

• Induced draft appliance

• Natural draft appliance

• Forced draft appliance

• Balanced draft appliance

In fan-assisted systems, what typically happens if the air supply size is reduced?

• Increased combustion efficiency

• Reduced static pressure

• Overheating of the appliance

• Poor venting performance

Annual Fuel Utilization Efficiency (AFUE) describes:

• Only the combustion efficiency of an appliance

• The seasonal efficiency, including heat losses

• The temperature of exhaust gases

• The fuel type used in an appliance

High-efficiency appliances often feature a secondary heat exchanger to:

• Increase fuel consumption

• Condense water vapor for added efficiency

• Raise exhaust temperature

• Lower combustion efficiency

What does a combustion air prove switch prevent?

• Over-pressurization

• Flame rollout

• Burner operation if airflow is insufficient

• Pilot flame extinguishment

What is one common material used in high-efficiency appliance venting?

• Copper

• PVC plastic

• Cast iron

• Asbestos