NSS Combustion and Venting Systems

Question 1

What vent pipe material is approved for use with Navien condensing tankless water heaters?

Accepted Answer

PVC/CPVC Schedule 40

Answer

Type B gas vent

Answer

Galvanized steel

Answer

Type L vent pipe

Question 2

What venting category classification applies to Navien condensing units?

Accepted Answer

Category IV

Answer

Category I

Answer

Category II

Answer

Category III

Question 3

What is the minimum required clearance between a Navien vent termination and an operable window or door?

Accepted Answer

12 inches

Answer

6 inches

Answer

18 inches

Answer

4 feet

Question 4

In a concentric (coaxial) vent system on a Navien unit, which pipe carries the exhaust gases?

Accepted Answer

The inner pipe

Answer

The outer pipe

Answer

Both pipes share exhaust equally

Answer

It alternates based on demand

Question 5

What is the required slope for horizontal vent pipe runs on a Navien condensing unit?

Accepted Answer

1/4 inch per foot back toward the unit

Answer

Level with no slope

Answer

1/4 inch per foot upward toward the termination

Answer

1/2 inch per foot toward the termination

Question 6

Which of the following is NOT an acceptable Navien vent termination location?

Accepted Answer

Directly into an unlined masonry chimney

Answer

Through an exterior wall

Answer

Through the roof

Answer

Under a soffit with proper clearances

Question 7

How many equivalent vent feet does a standard 90-degree elbow add to the total vent length calculation for Navien units?

Accepted Answer

5 feet

Answer

2 feet

Answer

10 feet

Answer

15 feet