RMGA Gas Appliance Installation and Service 2

Question 1

What is the function of a gas appliance's thermocouple or thermopile?

Accepted Answer

To sense pilot flame presence and hold the gas valve open only when the pilot is lit

Answer

To ignite the main burner

Answer

To measure flue gas temperature

Answer

To regulate gas pressure to the burner

Question 2

What causes 'yellow tipping' or 'lifting' of a natural gas burner flame?

Accepted Answer

Improper air-to-gas ratio—yellow tipping indicates incomplete combustion, lifting indicates too much primary air

Answer

Excessive gas pressure only

Answer

Faulty thermocouple

Answer

High humidity in the ambient air

Question 3

What is the purpose of a draft diverter (draft hood) on a natural gas furnace or water heater?

Accepted Answer

To isolate the appliance combustion zone from flue pressure variations and allow dilution air to mix with flue gases

Answer

To increase the draft in the flue to improve combustion efficiency

Answer

To reduce gas pressure entering the burner

Answer

To prevent backflow of combustion gases into the appliance

Question 4

What is the minimum clearance required above a gas range burner grate to combustible overhead cabinets under NFPA 54?

Accepted Answer

30 inches

Answer

12 inches

Answer

18 inches

Answer

24 inches

Question 5

What type of venting material is prohibited for natural gas appliance Category I venting applications?

Accepted Answer

PVC or CPVC plastic pipe

Answer

Type B double-wall vent pipe

Answer

Single-wall galvanized sheet metal vent pipe

Answer

Type L vent pipe

Question 6

What is the correct action if a technician detects a gas leak at a union fitting on a gas range supply line?

Accepted Answer

Shut off gas at the appliance valve, evacuate if necessary, and repair or replace the leaking fitting before restoring service

Answer

Tighten the union while gas is flowing and test with soapy water

Answer

Apply leak stop compound to the union and restore service

Answer

Increase gas pressure to re-seat the union seal