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While all the furnaces we install provide reliable heating to your home during the winter, they’re not all the same. Gas and electric furnaces are very different from one another in the ways they generate heat, how efficient they are, how they need to be installed, and how much they cost to run. In this article, we’ll review what gas and electric furnaces are and how they work. We’ll also discuss how to go about finding the right heating system for your home here in Lafayette.

4 key differences between gas and electric furnaces

As it turns out, despite both being “furnaces” in name, there are many differences between gas and electric furnaces. Here’s what you need to know about both:

An electric furnace installed in a local home here in Lafayette, Louisiana.


Method of heating

Gas furnaces combust fuel—in this case, natural gas—to generate heat energy. This combustion process occurs in a sealed, airtight chamber inside of the furnace, and the heat generated is then transferred to the air blown in by the blower. This heated air is then pushed out to your home through the air ducts.

With an electric furnace, there is no combustion or use of fuel. Instead, electricity is circulated through resistance coils inside of the furnace. These coils become red hot, and heat is generated. The blower then pushes air past these coils, warming it up before it enters the ducts of your home. An electric furnace operates similarly to a hairdryer, using electrical resistance to generate heat.


A gas furnace’s efficiency can be measured by its Annual Fuel Utilization Efficiency (AFUE) ratio. This measures how much heat is generated by the combustion of the fuel source. A furnace with a 92% AFUE is able to turn 92% of all its natural gas to heat, with about 8% being lost in exhaust gases. Since the early 1990s, the floor for furnace efficiency has been 78%, but many of the high-efficiency furnaces manufactured today near 98% or 99% AFUE.

Many electric furnaces have 99%-100% AFUE. This means that all the electricity they use is converted into heat energy. In many cases, this makes an electric furnace more efficient than a gas furnace, but there’s an important catch. We’ll discuss that in the section below.

Setup & Installation

Obviously, a gas line and gas connection is a prerequisite for a gas furnace. If your home does not have a natural gas connection, you’ll need to talk to your utility company about your options and what is available in your area.

Gas furnaces also need special ventilation and exhaust vents to remove the gas byproducts of the combustion process from your home. In contrast, electric furnaces are self-standing units and do not typically need exhaust vents to be installed.

Energy Costs

As reviewed above, electric furnaces often have a better AFUE than gas furnaces, making them more efficient. However, this is really an apples-and-oranges comparison. In most parts of the country—including here in South Louisiana—electricity is more expensive than natural gas. So, while an electric furnace may be more efficient at turning its fuel source into heat energy, you’ll often end up paying more to operate an electric furnace than a gas furnace.

In most cases, our team will recommend that homeowners without a gas line connection take a look at installing a heat pump instead. Not only are heat pumps ideal for our mild winters here in South Louisiana, but they can also provide energy-efficient cooling in the summer. This two-in-one system is perfect for many homes.

One important exception: if your home has rooftop solar and you plan to use some of the electricity generated for heating, an electric furnace might make sense since you’re essentially getting its “fuel” for free from sunlight. Be sure to talk to our team and your solar installer for more details about setting this up.

Give us a call to learn more

At Southern Air Heating & Cooling, our team installs both gas and electric furnaces from Trane and Carrier. Our team of experienced, certified technicians can help find the right furnace (or heat pump) for your home. To get started, give us a call here in Lafayette for a free in-home estimate.