The recent cold snap made you think it’s time to replace your old furnace. Freezing temperatures in South Florida aren’t common, but the last two winters have been pretty miserable. If you’re looking at energy-efficient models, you may be wondering what is AFUE?

Let’s look at what this anacronym means and how it helps you find the best furnace for your money.

What Does AFUE Stand For?

AFUE stands for Annual Fuel Utilization Efficiency, and it’s a way of documenting how efficient any furnace operates over the span of a year.

The rating is expressed as a percentage, which is how much of the fuel consumed is converted into useable heat. This rating usually spans from 30 percent to 100 percent.

Understanding AFUE

Shouldn’t your furnace turn 100 percent of the fuel into heat? Ideally, yes, but there are several other factors in play.

Firstly, fuel efficiency varies by the type of fuel used. Modern gas furnaces, for example, have ratings of 81 to 98 percent. Oil furnaces offer less efficiency and fall between 81 and 87 percent.

Heat is produced when the fuel burns and is distributed through the ductwork by a fan via a heat exchanger. But not all of the heat produced during combustion makes it to the heat exchanger. Some is vented out, along with dangerous gases like carbon monoxide.

How do you calculate AFUE?

The method for calculating the AFUE of any furnace is determined by the American National Standards Institute (ANSI) and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE).

Once a model has been tested, the final data is calculated. The AFUE rating is determined by dividing the amount of heat produced in Btus by the amount of fuel consumed.

What is a good AFUE rating?

The higher the percentage, the more efficient the furnace. You’ll find a furnace’s AFUE rating on the bright yellow Energy Guide label on the unit.

Note that AFUE percentage is only the percentage of heat that is blown into the ductwork. There may be further heat loss in the ductwork.

The Energy Star program states that for gas furnaces, a 90 percent AFUE for gas furnaces in the South and 95 percent for gas furnaces in the North are considered high efficiency. Oil furnaces should have an AFUE of 85 or greater.

But I Wanted a Heat Pump

Heat pumps are common in South Florida because of the low demand for heating. They also pull dual-duty, providing both heating and cooling in mild climates.

However, heat pumps are rated differently. Their heating is rated with an HSPF number – or Heating Seasonal Performance Factor. Their cooling efficiency is rated with the EER, or Energy Efficiency Ratio.

Whether you prefer a new furnace or heat pump, the one thing for sure is that you don’t want to suffer through another cold, clammy winter without relief.

Make an appointment today with One Hour Air in Stuart today for an estimate on a new energy-efficient heat pump or furnace.