Skip to main content

80% Vs 95%: What Do Furnace Efficiency Ratings Mean?

Written by Comfort Solutions HVAC on . Posted in .

Your Easton, PA HVAC Team Explains the Difference

If you are looking to install, or replace an existing HVAC system, you want to do some basic research, and understand the variants you can choose from. As any furnace expert will tell you, one of the key criteria in furnace selection is the Annual Fuel Utilization Efficiency (AFUE). Most furnaces feature an AFUE of 80% or 95%, and as is obvious, higher the number, greater the efficiency. Although opting for a high-efficiency system may be tempting, it may not necessarily be the best choice to meet your heating goals. 

The HVAC specialists at Comfort Solutions demystify furnace energy efficiency ratings, and help you make the right choice for your home.

Key Differences Between 80% and 95% AFUE Furnaces

While 80% AFUE indicates a standard efficiency furnace, high efficiency furnaces typically offer an AFUE of 90% or more. 95% AFUE is fairly common among the newer gas-powered furnaces available today. Here are the key differences between standard efficiency and high efficiency furnaces:

  • Mechanism: An 80% AFUE furnace sucks air from the surrounding indoor area to generate energy from natural gas, also known as ‘open combustion’ mechanism. A 95% AFUE furnace works on a sealed combustion mechanism, sucking in air from the outdoors via a dedicated PVC pipe.
  • Cost: The unit, as well as its installation cost may be vastly different between the two furnaces. Replacing an 80% furnace that is in a crawl space or vented attic with a 95% unit would mean a tricky installation that adds to the cost and effort. Essentially, the furnace technician will have to insert a PVC pipe to create a pathway suitable for the combustion mechanism of the high-efficiency system.
  • Safety: Depending on the unit and the way it is installed, the gases produced by the combustion process could pose a safety risk to the occupants. While 80% units are safer in a vented area, 95% units are better suited to unvented environments. If your old 80% furnace was in a sealed attic or closed-off crawl space, consider a 95% AFUE furnace, as and when you decide it’s time for an upgrade. 

The furnace that makes most sense for your home would depend on: 

  • Your energy efficiency goals
  • The existing location of your furnace
  • The venting, ducting and other attributes of your home
  • Your budget

However, if energy efficiency is your primary concern, you may want to look at two other aspects in addition to the AFUE:

  1. Stages of Heat:  Single-stage furnaces can only be set to full blast mode, and these units use the maximum possible capacity to blow hot air into your home. Two-stage furnaces have an additional ‘slow speed’ setting. They typically use 65% of the furnace capacity, saving significantly on energy consumption.
  2. Airflow: Similar to the heat stages, some furnaces offer a simple ‘on’ airflow, while others come with ‘variable’ air flow. The latter allows you to regulate the amount of hot air that enters your home at any given time, making these units more efficient than standard units.

Since the single-stage or two-stage options are available in both, 80% furnaces and 95% furnaces, you should take a comprehensive view before finalizing your new unit. For example, a two-stage 80% furnace may be more energy efficient than a one-stage 95% one. 

No matter what your heating or cooling goals, if you are looking to replace or install a new HVAC system, rely on the licensed and qualified technicians at Comfort Solutions HVAC. We conduct a thorough inspection of your existing system, home layout, and other key factors, before advising you on units that best meet your requirements and budget. Our wide range of heating and cooling solutions focus on improving the comfort and energy efficiency of your living spaces.

Looking for reliable, affordable furnace installation, repairs, or tune-ups? Speak to the experts at Comfort Solutions HVAC at 610-438-9300 or contact us online.