FC FC Venting & Exhaust Systems

Question 1

Which furnace venting category uses PVC plastic pipe for the flue because flue gas temperatures are low?

Accepted Answer

Category IV

Answer

Category IV furnaces (high-efficiency condensing) have low flue temperatures and positive vent pressure, requiring corrosion-resistant plastic pipe like PVC or CPVC.

Question 2

What is the minimum slope per foot required for horizontal PVC vent pipe on a condensing furnace to allow condensate to drain back to the furnace?

Accepted Answer

1/4 inch per foot toward the furnace

Answer

Horizontal PVC vent sections must slope at least 1/4 inch per foot back toward the furnace so condensate drains to the trap rather than pooling in the pipe.

Question 3

How far must a direct-vent (concentric) termination kit terminate above the ground in a US snow region?

Accepted Answer

18 inches

Answer

In areas subject to snow accumulation, direct-vent terminations must be at least 18 inches above grade to prevent obstruction by snow.

Question 4

What is the purpose of the concentric vent system on a direct-vent condensing furnace?

Accepted Answer

To use one pipe for exhaust and a surrounding outer pipe for combustion air intake

Answer

Concentric venting combines the exhaust flue (inner pipe) and combustion air intake (outer annulus) in one penetration through the wall or roof.

Question 5

A Category I naturally venting furnace must be vented with which type of material?

Accepted Answer

Type B double-wall metal vent pipe

Answer

Category I appliances require Type B double-wall vent pipe for the vertical section because flue temperatures are high enough to require insulated metal venting.

(FC) Furnace Installation and Maintenance Certification Practice Test

(FC) Furnace Installation and Maintenance Certification Practice Test

FC FC Venting & Exhaust Systems