If you're in the market for a new furnace, one of the first things you'll encounter are furnace efficiency ratings. These ratings tell you how much of the fuel the system uses that goes directly into your home as heat and how much the furnace wastes. There's a close relationship between the ratings and the size and price of the furnace you need for your home.
The efficiency ratings for gas furnaces are called AFUE (annual fuel utilization efficiency). The minimum starts at 80 which means that the furnace uses 80 percent of the fuel it consumes for heating your home and it wastes 20 percent of the gas up the chimney or elsewhere. Systems are available with AFUE ratings as high as 99 percent, indicating they waste a mere 1 percent of the fuel they use.
Furnaces whose AFUE ratings are over 90 are usually condensing furnaces and they use a second heat exchanger to extract the heat from the water vapor burned gas creates. These systems have a slightly different configuration than the normal gas furnace and a higher price tag, but their efficiency promises significantly lower energy bills for years to come, offsetting the cost. Some units provide up to 98% efficient capabilities!
Mid-range furnace efficiency ratings have AFUE ratings in the mid-80s and if your home won't easily accept a condensing furnace, such a furnace is likely to provide you with higher efficiency than your current system offers. Some of these use two-stage heating, an energy saver when temperatures are milder and your home's heating needs are lower.
The size you need and the AFUE rating are related. Since a furnace with a higher AFUE puts out more heat, you may not need as large a system, which generally costs less. The HVAC contractor you work with should perform a load calculation using Manual J and S, both of which take into account the variables in your home that contribute to the system size you need.
To learn more about furnace efficiency ratings, contact the pros at Air Assurance, providing outstanding HVAC services for homeowners in the Broken Arrow area since 1985.
Our goal is to help educate our customers in the Tulsa and Broken Arrow, Oklahoma area about energy and home comfort issues (specific to HVAC systems).
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