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How Does an Electric Furnace Work?

As we find ourselves deep in winter, it’s only natural to think about something that’s on many of our minds during the chilly months: staying warm! Creating and maintaining sources of heat have been some of the most vital, life-preserving actions in the thousands upon thousands of years of human history. From huddling around campfires in caves or warming our hands by wood-burning stoves to installing modern, high-tech central heating solutions, humans have always done our best to keep warm when it’s cold out.

But while it’s easy to understand how a campfire can keep you warm, modern furnaces are a little more inscrutable. To many, a furnace is just a mysterious metal box that blows hot air into your workplace or home. The internal mechanics might as well involve tiny wizards working around the clock to heat things up. In this blog post, we’ll answer the question, “How does an electric furnace work?” and compare it to its most common alternative, a gas furnace.

How Do Furnaces Work?

To answer the question, “How does an electric furnace work,” we should first answer the question, “How does any furnace work?”

In fact, the question can be made broader still: from the earliest campfires to modern central heating installations, any system made to warm an area works on one of the most fundamental principles of thermodynamics: temperature is transferrable.

When you put a kettle on an electric stovetop, the stovetop grows warm and transfers that heat to the kettle. This transfers the heat to the water, boiling it for tea. If you find that your tea is too warm, you can drop an ice cube in it. The frozen water and hot tea transfer their temperatures to each other, resulting in a warmer (i.e., melted) ice cube and a cooler cup of tea.

Heating systems work in the same way. By creating a point of heat and then drawing air through or past it, you can transfer that heat to the air and then disperse the air through the space to be kept warm. Whereas campfires or wood-burning stoves generate smoke and ash—meaning that some of the heat byproducts aren’t safe to breathe—modern heating systems keep the heated air entirely separate from the heat source.

Beyond the hazards of smoke, something like a wood-fired stove isn’t very effective at heating a large area. Even if you can separate the heated air from the smoke, there’s nothing pushing the air along except more air. This means it might not move that heated air to the rooms you want to make warmer.

Fortunately, modern furnaces solve both of these problems.

How Does an Electric Furnace Work?entek-how-does-an-electric-furnace-work

Whether electric or gas, a furnace creates heat using the same basic principles outlined above. When a thermostat detects that the temperature has fallen below the desired level, it signals to the furnace to begin the heating process. The heating element in the furnace itself then activates, creating warmth. An electric motor pumps cool air in from an outside source. That air passes over or through the heating elements. Then the forced-air system blows that heated air through the ducts and into your rooms.

Any furnace works on this basic principle, but let’s look more specifically at electric ones.

When the thermostat sends the “it’s too cold” signal to an electric heater, it activates its heating elements, which are tightly coiled spools of wire, similar to the ones you might find in a toaster. Sending an electric current through these coils heats them up due to their resistance, and the greater the need for heat, the higher the number of elements activated.

A motor will activate. It uses a blower system to draw cool outside air into the furnace through a filter. The filter is important because it gets rid of dust and other particulate matter. Then the blower passes the air directly over the red-hot heating element. The blower then pushes the air out of the furnace into the ductwork and into your home. As there are no hazardous parts to the heating elements, it’s safe for the air to pass directly over them.

Electric vs. Gas Furnaces

A gas furnace doesn’t differ in the basic concept outlined above, but there are a few extra steps. Whereas an electric furnace uses electric heating elements to create warmth, a gas furnace uses natural gas, which it ignites in a combustion chamber to produce heat. Combustion requires fresh air, but it also generates poisonous byproducts like carbon monoxide, which must be kept separate from the air sent into your home.

Unlike an electric furnace, which just has one stream of air—cool air in, warm air out—a gas furnace must have two streams of air:

  1. A stream that brings cool air in, heats it, and sends warm air through your home
  2. A stream that brings air into the combustion chamber and expels it outside as exhaust

This means that rather than just blowing air over heating elements, the clean air must be kept separate, typically by piping it through the heat created by the combustion process.

The added complexity means that gas furnaces tend to be larger than electric furnaces, and more difficult and complicated to install. Gas furnaces also carry an added risk. If chambers aren’t properly sealed or wear down over time, a breach can introduce harmful carbon monoxide into your heating system, a potentially deadly gas. For this reason, if you have a gas furnace, it’s critical to have a carbon monoxide detector.

However, gas furnaces can typically be cheaper to run, as the cost of gas is typically lower than the cost of electricity. For this reason, gas furnaces are particularly common in colder climates. Here, round-the-clock heating may not only be nice to have but may be literally lifesaving when the temperatures drop.

Whether you have a gas furnace or an electric one, it’s important to maintain efficiency with proper upkeep and maintenance. For installation or repair work in the Portland metropolitan area, contact Entek HVAC.

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