How Does A Home Furnace Work

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Living in the Minneapolis/St. Paul region, residents depend on their home’s furnace to keep them warm and safe throughout the long, cold winter. While other parts of the country understand what winter really means, up North, we have some of the most brutal cold imaginable. Without a functional furnace, you could not survive, even indoors. So it is crucial to understand how these essential pieces of equipment keep you safe and warm in your home.


Most homes in the air use forced air furnaces for heat. The process that these units use looks like this:

  • Natural gas or propane, the fuel, is ignited in the burner.
  • The flame created by the gas heats a metal heat exchanger and is exhausted out a flue.
  • That warmed heat exchanger transfers the heat it absorbs to the incoming air to make it warm.
  • The blower on the furnace moves the now warmed air into the ductwork that carries it throughout your house.
  • The warm air circulates into each room of the house while the more dense cold air is drawn back to the furnace using the return ductwork, where it is reheated and starts its return trip to warm your house.


There are several vital items in the furnace that are needed to keep your house warm. This list of vital components includes:

  • Thermostat – this is a temperature-activated switch that controls the operation of the furnace. When the temperature drops below the desired setting, it activates the furnace. It also turns off the furnace when the desired temperature is attained.
  • The Draft Hood Or Fan – this fan helps to make the combustion process more energy efficient. It mixes air with the gas to optimize the fire combustion process and keep your heating costs affordable.
  • Burners – the burners in a furnace look much like the gas lines on a gas grill. They also work with the gas valve, ignitor, and flame sensor to control the flame and keep it warming the heat exchanger.
  • Heat Exchanger – these are a series of metal tubes that get heated by the burner to heat the air inside them. The most efficient heat exchangers use curves to slow the airflow and maximize the heat transfer rate to better heat your home.
  • Blower – the blower fan moves the air through the ducts after it has been heated. Some ultra-efficient units offer a variable speed fan for lower energy consumption.
  • Flue – The flue vent allows the gases from the combustion process to be safely removed from your home. This item is essential to avoid a build-up of toxic carbon monoxide in your home.


The experts at Blue Ox Heating And Air are here 24/7 to assist with any furnace issues you encounter this winter. In addition, we highly recommend a furnace tune-up before the start of the heating season to ensure that your home remains warm and safe. Call 952-208-4570 to schedule a tune-up or service from our furnace pros.