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How Does a Furnace Work?

If you have an older heating system in your home, chances are good that it’s a furnace. Furnaces are among the oldest of all residential heating systems. In their earliest days, they were fueled with coal and wood. Newer models use electricity, gas, or propane, and can run at high efficiency levels. Some have AFUE (annual fuel utilization efficiency) ratings of 98%, which means they turn 98% of the fuel they consume into heat.

But how exactly do these grand warhorses of the HVAC world work? Or at least the modern one sitting in your house right now, doing the heating for the fall? Here’s a short rundown on the operation of the contemporary furnace.

If you need more help with a furnace, whether  it’s maintenance or repairs, or if you want a new one installed, look to the Eugene, OR heating specialists at Comfort Flow Heating.

Whatever fuel a furnace uses, it operates on the principle of forced air heating. The furnace transfers heat to air, which blower fans then send through the ductwork of a house and out vents. Furnaces often share the duct system with an air conditioner so homeowners don’t need to take up additional space for their cooling system.

In a natural gas furnace, a pilot light ignites a series of burners inside a combustion chamber. The heat these burners create then enters the heat exchanger, where the heat transfers to the air and raises it to the temperature set by the thermostat. At this point, the blowers take the air and send it through the ducts. Propane furnaces operate on a similar principle.

For an electric furnace, instead of a pilot light, an electrical ignition begins the heating process. In place of gas-powered burners, the ignition activates heating elements that contain conductive coils. As current passes through the coils, they begin heating the air for the blowers to handle. The more heat the thermostat calls for, the more heating elements turn on.

This sounds deceptively simple, but furnaces contain many components to ensure that the heat exchange and distribution runs smoothly and without safety concerns. Trying to diagnose or fix a malfunctioning thermostat on your own is not recommended unless you have extensive HVAC training and the appropriate tools. You should rely on experts to handle whatever ails your furnace, no matter its power source. (Gas furnaces can lead to carbon monoxide poisoning, and electric furnaces may cause high voltage shocks.)

Keep your Eugene, OR heating system—whether furnace, heat pump, radiant floor heating, or geothermal—running effectively for you through fall and winter: get the advice and help of Comfort Flow Heating. We’ve been in business for 50 years, and we already know your furnace down to its smallest part.

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