G3 G3 - Gas Technician Level 3 Appliance Installation and Service Questions and Answers 3

Question 1

A gas furnace is short-cycling (turning on and off rapidly). The most likely cause is:

Accepted Answer

Overheating due to restricted airflow causing the high-limit switch to trip

Answer

Restricted airflow causes the heat exchanger to overheat, tripping the high-limit safety switch and shutting off the burner prematurely.

Question 2

When a gas appliance produces a strong smell of sulfur (rotten eggs) after lighting, the technician should:

Accepted Answer

Immediately shut off the gas supply and investigate for a gas leak

Answer

Sulfur odor indicates the odorant added to natural gas, signaling a possible gas leak that requires immediate shutdown and investigation.

Question 3

If a gas boiler pressure relief valve (PRV) is dripping frequently, the technician should first check:

Accepted Answer

System pressure and the expansion tank charge for correct pre-charge pressure

Answer

A PRV that opens repeatedly usually indicates the system pressure exceeds its set point, often due to a waterlogged or improperly charged expansion tank.

Question 4

A gas appliance vent pipe is found to be incorrectly sloped downward toward the appliance. This is a problem because:

Accepted Answer

Condensate and flue gases will not flow toward the exterior, risking backdrafting and CO spillage

Answer

Vent pipes must slope upward toward the termination to ensure condensate drains away and flue gases rise and exit the building.

Question 5

During a combustion analysis on a gas furnace, the technician measures an O2 reading of 15%. This indicates:

Accepted Answer

Excessive dilution air (too much excess air), reducing combustion efficiency

Answer

An O2 reading of 15% indicates far too much excess air is entering the flue, diluting combustion gases and wasting heat energy.

G3 - Gas Technician Level 3 Certification Practice Test

G3 - Gas Technician Level 3 Certification Practice Test

G3 G3 - Gas Technician Level 3 Appliance Installation and Service Questions and Answers 3