FC FC Venting & Exhaust Systems 2

Question 1

What is the primary danger of a blocked or restricted furnace flue vent?

Accepted Answer

Combustion gases including carbon monoxide will spill into the living space

Answer

A blocked flue prevents combustion gases from exhausting, causing them to spill into the living space and creating a potentially fatal CO hazard.

Question 2

When two or more gas appliances share a common vent, which appliance should be connected closest to the chimney?

Accepted Answer

The appliance with the highest BTU input

Answer

The appliance with the highest BTU input (most flue gas volume) should connect nearest the chimney to minimize back-pressure on smaller appliances.

Question 3

Which condition causes condensation and flue gas spillage in an oversized masonry chimney venting a high-efficiency furnace?

Accepted Answer

The large chimney volume cools the small volume of low-temperature flue gas before it can draft properly

Answer

An oversized chimney has too much volume relative to the small flue gas output of a high-efficiency furnace, causing cooling, condensation, and loss of draft.

Question 4

What is the minimum upward slope required for horizontal sections of Category I single-wall vent connector pipe?

Accepted Answer

1/4 inch per foot rise toward the chimney or vertical vent

Answer

Horizontal vent connectors must rise at least 1/4 inch per foot toward the chimney to help flue gases rise by natural draft.

Question 5

What causes a furnace vent to backdraft when exhaust fans operate in the home?

Accepted Answer

Exhaust fans depressurize the home, creating negative pressure that reverses natural draft in the flue

Answer

Large exhaust fans can depressurize a home enough to overcome chimney draft, pulling flue gases back down the vent and into the living space.

(FC) Furnace Installation and Maintenance Certification Practice Test

(FC) Furnace Installation and Maintenance Certification Practice Test

FC FC Venting & Exhaust Systems 2