G3 G3 - Gas Technician Level 3 Appliance Installation and Service Questions and Answers 2 — Questions and Answers
Question 1: When servicing a gas burner with an intermittent pilot ignition (IPI) system, if the pilot fails to ignite, the technician should first check:
- The main burner orifice size
- The spark igniter gap and electrode condition (Correct answer)
- The flue size
- The gas meter pressure
Correct answer: The spark igniter gap and electrode condition
A worn, fouled, or improperly gapped spark electrode is the most common cause of IPI pilot ignition failure.
Question 2: What is the purpose of a thermocouple in a standing pilot gas appliance?
- Measure room temperature for the thermostat
- Generate a millivolt signal to hold the gas valve open when the pilot flame is present (Correct answer)
- Regulate gas pressure to the burner
- Ignite the pilot automatically
Correct answer: Generate a millivolt signal to hold the gas valve open when the pilot flame is present
A thermocouple converts pilot flame heat into a small millivoltage that energizes the safety gas valve, preventing gas flow if the pilot extinguishes.
Question 3: During annual service of a gas water heater, a technician notices a yellow-tipping flame. This most likely indicates:
- Excess primary air
- Insufficient primary air causing incomplete combustion (Correct answer)
- Correct air-to-gas ratio
- High gas pressure
Correct answer: Insufficient primary air causing incomplete combustion
Yellow-tipping flames indicate incomplete combustion due to insufficient primary air mixing with the gas before burning.
Question 4: A gas appliance heat exchanger should be inspected annually primarily to detect:
- Rust on the outer casing
- Cracks or holes that could allow combustion gases to mix with circulated air (Correct answer)
- Correct burner color
- Thermostat calibration errors
Correct answer: Cracks or holes that could allow combustion gases to mix with circulated air
Cracks in the heat exchanger allow carbon monoxide from combustion gases to enter the living space, creating a serious health hazard.
Question 5: When replacing a gas valve on a furnace, the technician must verify the new valve:
- Is painted the same color as the original
- Has the same inlet/outlet pressure ratings and voltage specifications as the original (Correct answer)
- Is the least expensive available option
- Has a longer warranty than the original
Correct answer: Has the same inlet/outlet pressure ratings and voltage specifications as the original
The replacement gas valve must match the original's pressure ratings, voltage, and BTU capacity to ensure safe and proper operation.
Question 6: After completing a gas appliance service call, the technician should always:
- Leave the gas supply off until the homeowner returns
- Perform a leak test on all disturbed connections using approved leak detection solution (Correct answer)
- Only test the main shutoff valve
- Skip testing if the repair seemed straightforward
Correct answer: Perform a leak test on all disturbed connections using approved leak detection solution
All disturbed gas connections must be leak-tested after service to ensure no gas leaks were introduced during the repair.
G3 G3 - Gas Technician Level 3 Appliance Installation and Service Questions and Answers 2
When servicing a gas burner with an intermittent pilot ignition (IPI) system, if the pilot fails to ignite, the technician should first check: