HVAC Unit 31 Gas Heat EXAM STUDY GUIDE
2026 COMPLETE QUESTIONS WITH CORRECT
DETAILED ANSWERS || 100% GUARANTEED
PASS <LATEST VERSION>
Section 1: Fundamental Principles & Safety
1. What is the primary purpose of a gas furnace?
a) To cool the air
b) To filter the air
c) To transfer heat to the air
d) To humidify the air
2. What is the standard measurement for gas heat?
a) Volts
b) British Thermal Units (BTU)
c) Amperes
d) Cubic Feet per Minute (CFM)
3. What is the primary safety device on a gas furnace that proves
flame?
a) Limit Switch
b) Pressure Switch
c) Flame Sensor
d) Thermocouple
4. What is the typical residential supply voltage for a gas furnace?
a) 120 VAC
,b) 24 VAC
c) 240 VAC
d) 12 VDC
5. The control voltage for most furnace safeties and the gas valve is:
a) 120 VAC
b) 24 VAC
c) 240 VAC
d) 12 VDC
6. What is the complete combustion of natural gas?
a) Natural Gas + Oxygen → Carbon Monoxide + Water Vapor + Heat
b) Natural Gas + Oxygen → Carbon Dioxide + Water Vapor + Heat
c) Natural Gas + Nitrogen → Carbon Dioxide + Soot
d) Propane + Oxygen → Carbon Dioxide + Water Vapor
7. Incomplete combustion is dangerous because it produces:
a) Carbon Dioxide
b) Oxygen
c) Carbon Monoxide
d) Nitrogen
8. Before working on a gas valve, a technician must:
a) Disconnect the thermostat
b) Shut off the gas supply and disconnect electrical power
c) Only shut off the gas supply
d) Only disconnect the 24V power
9. The "call for heat" originates from the:
a) Gas Valve
b) Induced Draft Motor
, c) Thermostat
d) Control Board
10. What is the purpose of a manifold on a gas furnace?
a) To distribute gas to the burners
b) To mix air and gas
c) To sense the flame
d) To vent combustion gases
Section 2: System Components & Their Functions
11. What device provides the initial spark or heat to ignite the gas?
a) Flame Sensor
b) Igniter
c) Thermocouple
d) Gas Valve
12. The hot surface igniter (HSI) is typically made of:
a) Copper
b) Silicon Carbide or Silicon Nitride
c) Steel
d) Aluminum
13. A standing pilot light is ignited by:
a) A hot surface igniter
b) An intermittent spark
c) A match or a built-in sparker
d) The main burner
2026 COMPLETE QUESTIONS WITH CORRECT
DETAILED ANSWERS || 100% GUARANTEED
PASS <LATEST VERSION>
Section 1: Fundamental Principles & Safety
1. What is the primary purpose of a gas furnace?
a) To cool the air
b) To filter the air
c) To transfer heat to the air
d) To humidify the air
2. What is the standard measurement for gas heat?
a) Volts
b) British Thermal Units (BTU)
c) Amperes
d) Cubic Feet per Minute (CFM)
3. What is the primary safety device on a gas furnace that proves
flame?
a) Limit Switch
b) Pressure Switch
c) Flame Sensor
d) Thermocouple
4. What is the typical residential supply voltage for a gas furnace?
a) 120 VAC
,b) 24 VAC
c) 240 VAC
d) 12 VDC
5. The control voltage for most furnace safeties and the gas valve is:
a) 120 VAC
b) 24 VAC
c) 240 VAC
d) 12 VDC
6. What is the complete combustion of natural gas?
a) Natural Gas + Oxygen → Carbon Monoxide + Water Vapor + Heat
b) Natural Gas + Oxygen → Carbon Dioxide + Water Vapor + Heat
c) Natural Gas + Nitrogen → Carbon Dioxide + Soot
d) Propane + Oxygen → Carbon Dioxide + Water Vapor
7. Incomplete combustion is dangerous because it produces:
a) Carbon Dioxide
b) Oxygen
c) Carbon Monoxide
d) Nitrogen
8. Before working on a gas valve, a technician must:
a) Disconnect the thermostat
b) Shut off the gas supply and disconnect electrical power
c) Only shut off the gas supply
d) Only disconnect the 24V power
9. The "call for heat" originates from the:
a) Gas Valve
b) Induced Draft Motor
, c) Thermostat
d) Control Board
10. What is the purpose of a manifold on a gas furnace?
a) To distribute gas to the burners
b) To mix air and gas
c) To sense the flame
d) To vent combustion gases
Section 2: System Components & Their Functions
11. What device provides the initial spark or heat to ignite the gas?
a) Flame Sensor
b) Igniter
c) Thermocouple
d) Gas Valve
12. The hot surface igniter (HSI) is typically made of:
a) Copper
b) Silicon Carbide or Silicon Nitride
c) Steel
d) Aluminum
13. A standing pilot light is ignited by:
a) A hot surface igniter
b) An intermittent spark
c) A match or a built-in sparker
d) The main burner
