NATE Gas Heating 3

Question 1

What is the minimum clearance from combustibles required for Type B vent pipe in most residential applications?

Accepted Answer

1 inch

Answer

6 inches

Answer

3 inches

Answer

No clearance required

Question 2

What does a cracked heat exchanger in a gas furnace risk introducing into the living space?

Accepted Answer

Carbon monoxide (CO) and other combustion byproducts

Answer

Nitrogen dioxide only

Answer

Natural gas from the supply line

Answer

Refrigerant vapor

Question 3

What is the purpose of the vent pressure switch on a two-stage condensing furnace?

Accepted Answer

Confirm the inducer is operating at proper speed and the vent is clear before allowing ignition

Answer

Verify combustion air is being supplied

Answer

Monitor return air static pressure

Answer

Control secondary heat exchanger temperature

Question 4

LP (propane) gas manifold pressure for residential furnaces is typically set to which value?

Accepted Answer

7–11 inches WC

Answer

3.5 inches WC

Answer

10–14 inches WC

Answer

0.5 PSI

Question 5

Which type of furnace venting uses a dedicated fresh-air intake pipe running alongside the flue pipe?

Accepted Answer

Direct vent (sealed combustion) system

Answer

Natural draft venting

Answer

Power vent system

Answer

Type B common vent

Question 6

What is the correct procedure when a gas leak is suspected at a furnace?

Accepted Answer

Do not use any electrical switches; leave the building and call the gas company

Answer

Turn on exhaust fans and relight the pilot

Answer

Apply pipe dope and continue operating the furnace

Answer

Increase gas pressure to identify the leak location