Gas Appliance Installer Licensing Exam

Gas Appliance Installer Licensing Exam Class B Practice Examination Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf

1. The primary purpose of a gas pressure regulator is to:

• Measure gas flow
• Maintain a constant downstream pressure
• Increase pressure to the appliance
• Remove moisture from gas lines

Rationale: Regulators ensure consistent pressure delivery to

appliances regardless of supply fluctuations.

• The minimum clearance from combustibles for a Type B vent must

follow:

• Building code only 1 / 3

• Manufacturer’s certified installation instructions
• Contractor preference
• Local fire department recommendation

Rationale: Certified installation instructions have legal authority over

clearances.

3. Propane is:

• Lighter than air
• Heavier than air
• Same density as air
• Only dangerous when heated

Rationale: Propane is heavier, so it pools low and increases explosion

risk.

4. Gas piping systems should be purged:

• Before pressure testing
• After installation and testing
• Only when leaks are found
• Never required

Rationale: Purging removes air after confirming system integrity.

5. A yellow, lazy gas flame indicates:

• High pressure
• Incomplete combustion
• Perfect burn
• Gas starvation 2 / 3

Rationale: Yellow flames signify poor combustion and high CO

potential.

6. Thread sealant on gas pipe joints must be:

• Any oil-based product
• Thread tape for potable water use
• Approved for gas service
• Silicone caulking

Rationale: Only sealants certified for gas ensure safe sealing.

7. A spill switch in a gas appliance:

• Controls gas pressure
• Stops appliance if venting fails
• Ignites pilot flame
• Filters combustion air

Rationale: It detects venting issues to prevent carbon monoxide

buildup.

8. Purging propane systems outdoors is required because propane:

• Smells unpleasant
• Is harmless outdoors
• Can accumulate and ignite indoors
• Dissipates faster indoors

Rationale: Propane is heavier and dangerous in enclosed spaces.

9. A drip leg (sediment trap) is installed to:

• Reduce static pressure
• / 3