HVAC State Test Prep 13

Hot air furnaces are self-contained and self- __________ units.

• healing
• enclosed
• cleaning
• stoking

Why does hot air rise?

• when heated it becomes lighter
• when heated it gains oxygen and floats
• when heated it becomes heavier
• when heated it sinks slowly

After the hot air loses its heat, it becomes cooler and __________.

• heavier
• lighter
• moisture laden
• freezes

What is the most popular furnace used to heat houses in this country?

• propane gas
• natural-gas
• butane gas
• coal gas

What controls the operation of the gas solenoid?

• igniter switch
• printed circuit switch
• blower switch
• thermostat

How hot does the air in the plenum have to be before the fan switch closes and the fan starts?

• 95 degrees F
• 100 degrees F
• 120 degrees F
• 125 degrees F

What is the voltage required for the fan motor to operate?

• 240
• 120
• 12
• 24

How low does the temperature in the plenum have to drop to cause the fan to stop?

• 100 degrees F
• 90 degrees F
• 85 degrees F
• 75 degrees F

Why do electric-fired furnaces need large amounts of current to operate?

• the heating elements draw high current
• the fans draw a lot of current
• the heat exchanger is very inefficient
• none of the above

How fast does the electric-fired furnace begin producing heat?

• 5 minutes
• instantly
• slowly
• none of the above