Annual Fuel Utilization Efficiency or AFUE is a calculation to derive the percentage of fuel conversion into heat. It denotes your furnace efficiency in operating under different fuels such as propane, oil, and natural gas.
We will compare two furnaces according to the AFUE ratings. It will help to understand AFUE and its importance for your furnaces.
Gas furnace with 70 AFUE and 95 AFUE. The numbers are the equivalent percentage of heat converted into heat. Here it will be 70 percent and 95 percent respectively.
AFUE ratings of HVAC equipment have come a long way from 50 to more than 95 percent. Furnaces are experiencing several leading technologies and the latest features.
With innovative technologies, efficiency has also increased significantly. Premium range of furnaces provides more than 95 percent AFUE ratings with Energy Star certification.
The AFUE ratings are an average calculation of annual fuel conversion into heat because weather patterns change in a different part of the year and affect fuel usage accordingly.
How to Calculate AFUE Ratings?
We need to know the amount of energy oil and natural as contains. An HVAC unit that consumes natural gas at a hundred percent capacity, should generate 36,000,000 J equivalent of power. However, the utilization of natural gas does not stand 100 percent.
AFUE Ratings: Output Energy/Input Energy (according to 100 percent efficiency)
Comparison between AFUE 70 and AFUE 95
- AFUE 70 means 70 percent heat conversion; similarly, AFUE 95 means 95 percent heat conversion. The higher the ratings, the better will be the performance.
- AFUE 70 is available in older models. Most of them are not in use. At the same time, AFUE 95 furnaces are top-tiered models, generally available with Energy Star certification.
- In a rough estimate, older furnaces with 70 AFUE consume more energy and eventually inflate utility bills. AFUE 95 is highly energy-efficient and can save up to $22.22 for every $100 you spend.
- Furnaces with AFUE 95 function as condensing HVAC products. It converts more energy into heat. The heating & cooling equipment condenses released water vapors and transforms them back to heat and power. These are highly efficient than non-condensing furnaces. If you live in colder climatic areas in Midwest and Northeast, the efficiency of the machines increases 5 percent. It restricts wastage of energy and keeps your indoor atmosphere in the best condition possible.
- On the other hand, AFUE 70 rated furnaces are older models with significantly lower energy efficiency and savings on the electricity cost during the unit’s lifetime. Generally, lifetime counts as 15 to 20 years.
- There are high chances that you would not find AFUE 70 furnaces currently because, in the US, minimum permissible AFUE ratings are 78 percent for standard or entry-level furnaces
- After that, middle-tiered furnaces come with 80 to 85 AFUE ratings, and finally, premium furnaces are offered 90 and above AFUE ratings.
Comparison of Energy Savings with AFUE 70 and AFUE 95 Furnaces
You will get to know the cost to operate HVAC products, savings after upgrading from AFUE 70 to AFUE 95, and the advantage of shifting fuel through a savings calculator. It is a rough estimate and not for official representation.
The savings calculator considers the following data and conditions.
- Average Natural Gas Price in the USA: $18.09 per thousand cubic feet
- Heating oil price: $2.80 per Gallon
- Propane price: $2.38 per Gallon
- Electricity price: 13.19 per kW
- Annual Heating Degree Days (30 years for the US): 4811
- Design Indoor Temperature: 70 Degrees F
- Design Outdoor Temperature: 16.7 Degrees F
- C-Factor (heat from other sources): 0.77
*All rates and numbers are average according to different conditions in different parts of the USA
Suppose you have a furnace with AFUE 70 ratings and now plan to upgrade to AFUE 95 furnace. We applied the data mentioned above and derived the following vitals about energy savings and monetary advantages over the years of furnace use.
AFUE 70 Furnace will consume energy worth $2328 in a year, whereas AFUE 95 Furnace will use energy worth $1715 per year.
Therefore, you will save 26 percent on energy bills with AFUE 95 furnace in a year. Savings will be $3063 in five years, $6126 in ten years, and $9189 in fifteen years.
Popular Furnace Brands Comparison (With 97 AFUE Rating)
|Model Number||Capacity (MBtu/hr)||AFUE||Annual Gas Use (MMBtu)||Annual Energy Use (kWh)||Annual Cost (National Average)*||Lifetime Cost to Operate**||% Saving over Standard Furnace|
|Arcoaire® VC 97 (F9MAE0601714A)||60||97||46.9||155||$509||$9,168||22%|
|Armstrong Air A97USMV (A97USMV070B12S)||66||97||64||299||$705||$12,683||21%|
|Bryant 987M (987MA42060V17A)||60||97.4||46.7||154||$507||$9,128||22%|
AFUE ratings of a furnace are proof of its performance. It would help if you always went for higher AFUE ratings. Most probably, you will also get Energy Star certification. We have compared AFUE 70 and 95, and by all means, the premium furnace is the better deal among these two for complete comfort at home.
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