There are several different types of gas furnaces, making it confusing and tedious to actually pick one. They vary in their fuel efficiency, temperature control capabilities, and of course, their cost. Throughout your search, keep a few things in mind.

Number one, efficiency measures the amount of fuel burned and the heat you get as a result. Poor efficiency means you’ll pay more for less heat. Number two, there are different furnace burner stages and blower types, which affect the cost and quality of the furnace. The myriad of pros and cons between models and efficiency levels can be daunting to sift through without a furnace repair technician to guide you.

Furnace Burner Stages and Blower Types

As you’re looking for a new furnace or perhaps looking to know more about the one you already have, you’ll see words like single-stage and dual-stage. These labels indicate the levels and power at which a furnace runs. The blower speed is either set or variable, which indicates how quickly a home or area can be thoroughly warmed.


This type of burner is found in the cheapest furnaces. It only operates in one setting, leaving you with little adjustability. This stage is commonly found in low-efficiency furnaces, which are generally older models or models used to warm smaller areas. If you live somewhere with mild winters, you’ll have little issue with a single-stage furnace.

Two or Dual-Stage

This category of burners offers two electronically controlled settings. Models with a dual-stage furnace run on either a high or a low setting, giving you a bit more variability in your temperature output. This stage is generally found in standard furnaces, as it offers enough adjustability for those in colder and warmer climates.


Furnaces with a modulating burner and blower have the ability to hold precise temperatures, making continual, fine adjustments to keep up with your thermostat setting. This is done using electronic controls for both the burner and the blower. Typically, you’ll find modulating furnaces in higher-efficiency models or standard models.

Efficiency Levels And What They Mean

Efficiency is the name of the game in furnaces. You want to pay only for the gas you’re using–although natural gas is relatively cheap, inefficiency will still add up over time. Furnaces with lower efficiency levels are going to be cheaper, leading some homeowners to opt for this option. This likely won’t matter much if you live in the south, where efficiency and power aren’t quite as imperative. High-efficiency furnaces will cost more upfront, but the savings only build with each new year because of the money saved on fuel. Every option has its perks, and much of the success of your furnace will depend on where you live.

Low-Efficiency Furnaces

Furnaces have their efficiency measured by Annual Fuel Utilization Efficiency (AFUE) rankings. A low-efficiency furnace has 78% as its lowest allowed efficiency measurement. This means that you’re only getting 78% of usable heat as your furnace burns. Again, this might not be much of an issue if you live somewhere down south. But for those who rely on their furnaces and need as much efficiency as they can get, 78% may not cut it. Other qualities of low-efficiency furnaces are:

  • Single-stage furnace. Runs at one speed.
  • Electronic ignition. Pilot light lights electronically.
  • Generally used in manufactured homes, with less area to heat.


These furnaces fall right into the average range of quality, cost, and efficiency. Most homeowners either own a mid-efficiency furnace or would opt for one in this range. The general capabilities are nothing to sneeze at, especially for those who don’t need their furnace operating over half the year and on a high setting. Again, though, the quality to look for in furnaces is efficiency. Even if you don’t use your furnace quite as often as someone would in the woods of Alaska, you still want to keep your costs low by having as much fuel turn to heat as possible. Here are the highlights of mid-efficiency furnaces:

  • 80% AFUE minimum, with some manufacturers making 83% AFUE furnaces.
  • Electronic ignition.
  • Single or two-stage design with a blower that is single or variable. A variable blower causes your home to heat faster before gradually reducing in speed.
  • Compatible with a variety of climates and demands.

High-efficiency gas furnaces

Highly efficient furnaces boast some impressive qualities, like an almost perfect AFUE percentage. You’ll end up paying more for the sophisticated technology and efficiency level, but for you and your family, that could be well worth it. Furnace models adorned with an Energy Star qualification, as many high-efficiency models are, offer tax benefits and different rebate options. The Energy Star mark also ensures that you are purchasing the best gas furnace for the environment, as the Energy Star program puts a lot of effort into reducing their appliances’ greenhouse gas emissions. Here are the other highlights of high-efficiency furnace models:

  • 90-98% AFUE score. These are the best ratings possible.
  • Most have Energy Star ratings, ensuring their efficiency is up to par.
  • Condensing heat design is responsible for greater efficiency.
  • Single-stage, dual-stage or modulating furnace.
  • Variable-speed blower.
  • Sealed combustion chamber–keeps the most heat in as possible and has no scam like a flood check hose. 

Final Remarks

Gas furnaces fall into three general categories: low-efficiency basic models, standard efficiency models, and high-efficiency models. However, the true tell of a furnace’s quality and capabilities lie in what you need it to do. If you don’t use your furnace more than a couple of months out of the year, it may be wisest to opt for a cheaper option and not worry as much about blower speed and efficiency. For those who live in colder climates, or have a larger area to heat, picking an efficient and powerful furnace could be the difference between a comfortable and miserable winter unless you are planning to sit around the fireplace every night.

Your comfort should take ultimate priority. Next, think of what you want your money to get you. Better furnaces cost more upfront, but savings do come in the long run. It’s a decision largely dependent on your preference–though you should have your preference backed with thorough knowledge.

Dominic Wong

Dominic Wong, holding a Master’s in Electrical Engineering from Stanford University, has 20 years of experience in the home appliance sector. He joined our website as a freelancer in 20119, sharing his deep understanding of appliance functionality, energy efficiency, and consumer trends. Previously, Dominic worked in appliance design and testing. His background also includes roles in product development and consumer research. An advocate for sustainable technology, he enjoys mountain biking and experimenting with smart home gadgets in his spare time.

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