How to Compare AFUE Gas Furnace HVAC Energy Efficiency Ratings
                     How to Compare AFUE Gas Furnace HVAC 
Energy Efficiency Ratings
If you are looking for a new gas furnace or boiler for your home, you are probably
confused about the ratings that are labeled on the gas furnace’s body. In the 
market, there are literally hundreds of different gas furnaces from which you can 
choose the best one according to your home HVAC needs. With the help of new 
technology, gas furnaces or boilers are becoming more energy-efficient, which 
will save you a ton of money from your annual HVAC cost. But when you go to 
buy one, you’ll notice that more energy efficiency means heavier price tag. That’s 
why it is essential to understand just how much energy efficiency is suitable for 
your home heating needs. Now, you need to know what AFUE is.
What is AFUE?
AFUE stands for Annual Fuel Utilization Efficiency. It measures the consumption 
of fossil fuel like oil or gas, depending on the furnace type to produce heat for 
your home or commercial usage. AFUE ratings can go up to 98% and go down 
below less than 80%. The newer gas furnaces have high AFUE ratings. So, what 
do these percentages mean? If the AFUE ratings say 96%, it means that the gas 
furnace will burn 96% of the gas fuel, and the rest of the 4% will go out through 
your vent pipes or your chimney and gets mixed with toxic gas produced in the 
process. The Federal Trade Commission has ordered to use AFUE or Annual Fuel
Utilization Efficiency ratings on all furnaces regardless of the types, water 
heaters, and boilers. As a result, you will be able to compare between different 
gas furnaces and buy the best one according to your requirements. Here are the 
comparisons between different AFUE gas furnace energy efficiency ratings that’ll 
help you pick the right gas furnace for your home.
 
Comparison of AFUE Gas Furnace Energy 
Efficiency Ratings
Comparison between Old and New Gas Furnaces Using the 
AFUE Ratings
Nowadays, as all the gas furnaces and water heaters need to use the AFUE 
ratings, you will not see any of the gas furnaces have a rating, which is less than 
80%. Sometimes you will see many of the gas furnaces have ratings over 90%. 
But this is not the same case for the old gas furnaces. Old gas furnaces have 
ratings between 50-70%. Also, by looking at the AFUE rating, you can see the new
features that are available on the new gas furnace and compare it to the old gas 
furnace. This will give you a brief idea about which one to buy according to your 
requirements and energy-efficiency parameters. If you have recently noticed that 
the pilot light of your gas furnace is burning, it is an indication that your gas 
furnace is old and less efficient. You should upgrade your gas furnace as soon as
possible. Even if you choose a gas furnace that has an AFUE rating between 80-
85%, it will bring a massive change in the overall performance of your gas 
furnace and save you a lot of money on electric bills. A mid-efficient gas furnace 
has a smaller diameter flue pipe, and combustion gas and the high-efficient gas 
furnaces have a secondary heat exchanger and a combustion chamber. The 
secondary heat exchanger collects condensed moisture from flue gas and re-
uses the heat to increase its efficiency.
Calculate the Amount of Money you can Save
When you are buying a new heating system or gas furnace for your home, you 
need to consider the requirements of the building, size of the rooms, etc. Building
requirements have changed from the last time you bought a heating unit for your 
house. There is a lot to keep in mind, such as interior design, insulation of your 
house doors and windows, and building usage. By using the stats given on the 
US Department of Energy website, you can calculate the total energy 
savings/$100, which is based on AFUE or Annual Fuel Utilization Efficiency 
ratings.
 
See the infographic summary here – Comparing AFUE Gas Furnace HVAC Energy
Efficiency Ratings [Infographic]

Comparing AFUE Gas Furnace HVAC Energy Efficiency Ratings
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