AFUE and your next furnace

Have a calculator handy when you start thinking about buying a new furnace.

You will want to calculate the pros and cons of the various brands of modern furnaces, which are far better than their predecessors. While their purchase prices may be higher than you like, their efficiencies will shave 10 percent, 20 percent or even more off your monthly heating bill, and they function for many years!

One handy guide is the AFUE, a label that tells you each furnace’s Average Fuel Utilization Efficiency. It tells you how efficiently a furnace turns fuel into heat for your home or business.

The range extends from 78-to-84 percent for a conventional furnace to darn near 99 percent for the most advanced new system with all the technological bells and whistles. (Electric furnaces can get 100 percent AFUE, but that rating is dimmed by the fact that electricity generally costs significantly more than gas or oil.)

Add it up

Here’s where you may want the calculator. The better the AFUE the better the technology – and the higher the price.

An oil furnace can get an AFUE of 80 to 90 percent, meaning 80-90 percent of the fuel is converted into heat.

A gas furnace can score an AFUE as high as 98 percent. That’s an A-plus in anyone’s score card.

These newer furnaces don’t just keep you warm. They provide a steady, even flow of heat – no more cold spots – and they do it more quietly than furnaces of yesteryear. They also generate cleaner air and their efficiency lessens the impact on the environment.

Do the math

Your task is to see which furnace meets your budget, your building and your future plans. Do you intend to stay there long-term or will you move within a few years?

An experienced contractor will help you select the right size and give you the pros and cons of each system.

In any event, follow the advice of the Department of Energy to make sure you have a sealed-combustion unit:

“Specify a sealed combustion furnace or boiler, which will bring outside air directly into the burner and exhaust flue gases (combustion products) directly to the outside, without the need for a draft hood or damper. Furnaces and boilers that are not sealed-combustion units draw heated air into the unit for combustion and then send that air up the chimney, wasting the energy that was used to heat the air.”

Long Island furnace questions? Lighthouse HVAC is available 24/7.