Furnace Operation and Components

This video tutorial explains the sequence of operation for a basic fired forced air furnace. It covers the initial setup, including the schematic and power connections, and details the operation cycle from room cooling to burner ignition and fan operation. The video concludes with the furnace entering a dormant state and previews the next topic on efficient furnaces.

What is the purpose of the high limit in the furnace's electrical circuit?

• To prevent overheating by cutting off power

• To increase the voltage to the transformer

• To activate the fan immediately

• To ensure continuous gas flow

What happens when the thermostat contacts close in the furnace system?

• The fan is immediately activated

• The gas valve is energized

• The burners are turned off

• The plenum starts to cool

How does the gas valve opening affect the furnace operation?

• It deactivates the thermostat

• It allows gas to flow to the burners

• It cools down the heat exchangers

• It stops the fan from running

What is the role of the heat exchangers in the furnace?

• To cool the air before it enters the room

• To regulate the thermostat settings

• To ignite the gas in the burners

• To transfer heat to the air passing through

At what temperature range does the fan typically turn on?

• 32 to 38 degrees Celsius

• 70 to 80 degrees Celsius

• 49 to 60 degrees Celsius

• 10 to 20 degrees Celsius

What is the function of the indoor fan motor in the furnace system?

• To ignite the burners

• To deactivate the gas valve

• To push warm air through the ductwork

• To cool the plenum

What triggers the gas valve to close in the furnace cycle?

• The thermostat contacts opening

• The fan reaching maximum speed

• The plenum cooling down

• The burners igniting

What happens to the fan after the gas valve is de-energized?

• It continues to run until the plenum cools

• It stops immediately

• It reverses direction

• It speeds up to maximum capacity

What is the state of the furnace when it is in a dormant state?

• The gas valve is open

• The standing pilot is lit

• The fan is running

• The burners are lit

What initiates the repetition of the furnace operation cycle?

• The gas valve is manually opened

• The thermostat is turned off

• The room starts to cool

• The fan reaches a high temperature