Annual fuel utilization efficiency rating (known as AFUE) is one of the most important specifications to consider when buying a new furnace. This value helps you understand how efficient your new furnace will be and how much money you'll need to spend on your utility bills. Surprisingly, it can also help you understand how comfortably a furnace will heat your home.

AFUE is a relatively straightforward metric, unlike air conditioners' more complicated SEER ratings. This simple percentage tells you precisely how much of the money you spend on your heating bill goes directly into producing heat for your home. Keep reading for three facts you should consider when comparing AFUE ratings on new furnaces for your home.

1. AFUE Ratings Fall Into Tiers

You can find furnaces with a range of AFUE ratings, but you'll notice that many of them tend to cluster around the same values. In particular, you may notice that many furnaces have an AFUE rating of 80%. This value doesn't occur by accident; instead, it results from federal minimum standards for furnace efficiency.

When purchasing a furnace, you'll typically need to choose between standard efficiency models with an 80% rating or high-efficiency models with 90% or higher AFUEs. While high-efficiency technically refers to any furnace with an AFUE of 90% or higher, many modern higher-efficiency units exceed this value by a comfortable margin.

2. Electric Furnaces Have 100% AFUE

The AFUE rating for gas or oil-burning furnaces measures how much combustion energy these units lose to waste heat. The heat from combustion is "locked up" in toxic exhaust gases. Your furnace's job is to transfer heat from the exhaust stream to the air in your home while leaving the gas behind. Whatever heat the furnace can't extract is lost as the exhaust gases leave your home.

However, electric furnaces work differently. An electric furnace can effectively convert all of its incoming energy into heat, so electric furnaces will always have a 100% AFUE rating. Does this mean electric furnaces are more efficient? Ultimately, it depends. Since electricity is typically more expensive than gas or natural oil, you'll typically find that electric furnaces cost more to operate in very cold areas.

3. High AFUE Goes Hand-in-Hand With Comfort

For natural gas furnaces, a higher AFUE model will often produce more comfortable and even heating due to the features these models use to achieve their high efficiency. For example, you'll commonly find multi-stage blowers and burners on high-end, high-efficiency furnaces. These features help to smooth out heating in your home by preventing the hot-to-cold cycles found in lower efficiency models.

While AFUE might be relatively simple to understand, many nuances exist. If you're about to install a new furnace in your home, it's worthwhile to carefully compare AFUE ratings and consider how they'll impact your home's long-term heating efficiency and comfort. For more information, contact a company like Allied Mechanical & Electrical, Inc.