How A Gas Furnace Works (Animated Schematic)

Summary

This video explains how a vertical furnace system works in a basement. When a homeowner adjusts the thermostat, the furnace activates. The draft inducer draws in air for combustion, and natural gas is ignited to heat up the furnace's heat exchanger. The heat exchanger transfers heat to the home's air, while combustion gases are safely vented. The blower motor circulates the warm air through ducts, ensuring the home's temperature reaches the desired level, satisfying the thermostat setting. The process provides an efficient, safe heating solution for the home.

Takeaways

• 😀 The video starts with a side view of a vertically installed furnace in a basement.
• 😀 A homeowner adjusts the thermostat from 66 to 72 degrees.
• 😀 The furnace's draft inducer engages and draws ambient air for combustion and venting.
• 😀 Natural gas is supplied through the gas valve and distributed to individual burners.
• 😀 Ignition occurs, heating the gas which then heats up the serpentine-shaped heat exchanger.
• 😀 The draft inducer pulls combustion gases through the heat exchanger, allowing heat transfer.
• 😀 The heat exchanger allows return air to flow across individual tubes without mixing with combustion gases.
• 😀 The draft inducer expels combustion gases through the flue to safely vent outside the home.
• 😀 As the blower motor activates, it removes cool air from the home and blows it across the heat exchanger.
• 😀 The heat exchanger transfers heat to the passing air, which is then distributed throughout the home via ducts and registers.
• 😀 The process continues until the thermostat's desired temperature is reached.

Q & A

What is the purpose of the draft inducer in the furnace system?

The draft inducer draws ambient air through the system to provide oxygen for combustion and ensures that combustion gases are safely vented out of the house.

How does the furnace system begin the process of heating the air in the home?

When the thermostat is adjusted, the furnace ignites natural gas, which heats up the burners, and the heat from combustion is transferred to the heat exchanger tubes.

What role does the gas valve play in the heating process?

The gas valve controls the flow of natural gas provided by the utility company, directing it to the individual burners where it is ignited.

How does the heat exchanger work in the furnace system?

The heat exchanger transfers heat from the combustion gases to the air without mixing the combustion gases with the indoor air, ensuring safe and effective heat distribution.

Why is the heat exchanger designed with serpentine-shaped tubes?

The serpentine shape maximizes surface area for heat transfer and ensures that the combustion gases travel a longer distance, allowing more heat to be transferred to the air.

What happens to the combustion gases as they travel through the heat exchanger?

As the combustion gases travel through the heat exchanger, they lose heat, transferring it to the air moving through the system.

How does the blower motor contribute to the heating process?

The blower motor draws cool air from the home through the return registers and blows it across the heat exchanger, warming the air before it is distributed through the home.

What is the role of the flue in the furnace system?

The flue carries the combustion gases, expelled by the draft inducer, safely out of the house to prevent harmful gases from re-entering the living space.

How is the warm air distributed throughout the home?

The warm air is distributed through the supply ductwork and registers, ensuring it reaches different areas of the home until the thermostat's desired temperature is achieved.

What triggers the furnace to stop heating the air?

The furnace stops heating when the temperature set on the thermostat is reached, indicating that the home has been sufficiently heated.