NATE Gas Heating

Question 1

What is the primary safety device that shuts off the gas valve if the pilot flame is extinguished on a standing pilot furnace?

Accepted Answer

Thermocouple

Answer

Pressure switch

Answer

Limit switch

Answer

Flame sensor rod

Question 2

What is the purpose of the heat exchanger in a gas furnace?

Accepted Answer

Transfer heat from combustion gases to the circulating air without mixing them

Answer

Mix combustion gases with supply air

Answer

Remove moisture from combustion products

Answer

Regulate gas pressure to the burners

Question 3

What component in an induced-draft furnace proves that combustion airflow is established before the gas valve opens?

Accepted Answer

Pressure switch

Answer

Thermocouple

Answer

Limit switch

Answer

Rollout switch

Question 4

What type of ignition system uses a glowing ceramic element to ignite the gas burners in modern furnaces?

Accepted Answer

Hot surface igniter (HSI)

Answer

Spark ignition

Answer

Standing pilot

Answer

Direct spark ignition

Question 5

What is the function of the rollout switch on a gas furnace?

Accepted Answer

Detect flame rollout and shut down the furnace if heat exceeds safe limits near the burner compartment

Answer

Monitor supply air temperature

Answer

Measure gas manifold pressure

Answer

Control the inducer motor speed

Question 6

What is the standard gas manifold pressure for natural gas residential furnaces in the US?

Accepted Answer

3.2–3.8 inches WC

Answer

7–14 inches WC

Answer

0.5–1.0 PSI

Answer

10–12 inches WC