True or False: Exhaust from high-efficiency furnaces is vented outside the building through plastic (PVC) piping.

True or False: Exhaust from high-efficiency furnaces is vented outside the building through plastic (PVC) piping.

• A. False
• B. True
• C. Not sure
• D. Sometimes

Answer: (B)

High-efficiency furnaces vent their exhaust through plastic piping because the combustion gases are cooler and the units are sealed, condensate-producing systems. This condensing design uses PVC (or CPVC) vent pipes to carry the exhaust outside and often uses a separate PVC intake pipe for combustion air. The cooler gases and the need to manage acidic condensate make plastic venting appropriate and code-compliant for these furnaces, unlike older atmospheric vented units that rely on metal flues to handle hotter gases. So, yes—the exhaust from high-efficiency furnaces is vented outside the building through plastic piping, with proper sizing, termination, and, typically, a dedicated intake pipe as well.

High-efficiency furnaces vent their exhaust through plastic piping because the combustion gases are cooler and the units are sealed, condensate-producing systems. This condensing design uses PVC (or CPVC) vent pipes to carry the exhaust outside and often uses a separate PVC intake pipe for combustion air. The cooler gases and the need to manage acidic condensate make plastic venting appropriate and code-compliant for these furnaces, unlike older atmospheric vented units that rely on metal flues to handle hotter gases. So, yes—the exhaust from high-efficiency furnaces is vented outside the building through plastic piping, with proper sizing, termination, and, typically, a dedicated intake pipe as well.