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Low-, Mid-, High-Efficiency Furnaces

In our last blog, we discussed furnace efficiency ratings: what are they? Who rates furnaces? What kinds of regulations are there? As promised, here’s more information about the specific ratings of furnaces.

While you’ll find endless styles and related venting options, you can get a sense of what you’re dealing with in your home through the following categories.


Older furnaces typically fall into the 56% to 70% AFUE range according to the Energy Department. You’ll spot a continuous pilot light in these models, and they are often known as single-stage furnaces. In other words, they turn on when it’s cold and turn off when your house warms up to the right temperature.

A simple exhaust system will depend on the natural draft of your house instead of fans and you typically won’t be able to adjust the speed of the blower.


Standard or mid-efficiency furnaces include the majority of systems today, ranging between 80% and 83% AFUE. These conventional gas furnaces cost between $900 and $1,800, a much lower upfront price tag compared to high-efficiency models. 

These systems may include an electric ignition or complex exhaust fans to direct heat and run smaller overall. You’ll find both single-stage and two-stage designs. Two-stage furnaces offer more heating control instead of simply switching between on and off.


If your furnace earned the Energy Star label, this means it boasts a 90% to 98.5% AFUE rating. A sealed combustion chamber is a key factor in these systems, ensuring the warm air stays in your home and the dangerous exhaust goes outside. The furnace may include a more advanced heat exchanger, ignition, variable blower, and two-stage or multi-stage heating design.

While these designs are not hard to find, they can cost between $3,000 and $4,000.

Quick Note on Electric Furnaces

The Energy Department notes that all-electric furnaces often feature some of the highest AFUE ratings on the market, but don’t jump at this option too quickly. The high cost of electricity in many regions of the country could outweigh its benefits, even if the price of an electric heater is lower upfront.

Other Contributing Factors

A well-insulated home and an efficient furnace go hand-in-hand. If you’re looking to buy a new furnace and are on the hunt for the right design, you may want to start by upgrading your home itself first. The better it holds in heat, the smaller the furnace you’ll need to keep it toasty.

Factors that directly affect the efficiency outside of AFUE include:

  • Attic and wall insulation
  • Energy-efficient windows and doors
  • Updated ductwork or chimney lining
  • Thermostat upgrade
  • Sealed entryways around pipes
  • Well-placed and maintained radiators
  • Clean furnace filters
  • Direct indoor sunlight

Choosing the Right Furnace for You

A new furnace should last a couple of decades when well maintained and properly designed. In addition to choosing among gas, oil, propane, and electric, choose an AFUE rating that makes sense for your climate. 

We are happy to help with all your heating needs. At Barber Heating & Air, we are dedicated to maintaining and installing the perfect system for your home. If you’re interested in how we can meet the energy needs for your Burlington, NC home, request a quote or call us at (336) 226-6959.

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