How much of your heating budget is going straight up the flue? It might be more than you think! Furnace efficiency is a prime consideration for most homeowners, so it helps to understand a little industry terminology, and what a furnace efficiency rating really means.
Annual Fuel Utilization Efficiency Rating
Regardless of the fuel source, every furnace manufactured is evaluated and assigned an annual fuel utilization efficiency rating, also known as an AFUE rating. An independent organization within the HVAC industry determines this rating by calculating how much of the available fuel is actually used to heat your home versus how much is lost through venting. The rating for furnace efficiency takes into consideration the normal cycling of the unit as well as energy losses that may occur as a result of load changes. In actual use, the AFUE can also be affected by adjustments the homeowner makes to the unit and weather changes.
How does that affect your wallet?
A simpler explanation is to think of the AFUE in terms of money. For example, if you have a furnace that is 95 percent efficient, 95 cents out of every heating dollar is actually used to heat your home. The remainder is vented out through your flue. If your furnace is only 75 percent efficient, you are losing 25 cents out of every heating dollar to venting. This means that even a relatively small change in the efficiency rating of your furnace can have a significant impact on your wallet and home comfort.
Department of Energy AFUE Standards for Furnace Efficiency
A few years ago the United States Department of Energy (which made this cool infographic on heating costs) increased the minimum AFUE standards for new furnaces. All new furnaces sold in the United States must meet these standards. Depending on the type of furnace or boiler the minimum AFUE rating is between 80 and 84 percent.
Furnaces manufactured before 1992 may have an efficiency rating as low as 70 percent.
Choosing an Energy Efficient Furnace
Furnaces that carry the Energy Star logo offer the highest level of efficiency. The following are features that you should look for to make sure your furnace is as efficient as possible.
- Choosing a unit with an electric ignition can improve efficiency by as much as 6 percent by eliminating the need for a continuously burning pilot light.
- A furnace equipped with a secondary heat exchanger allows you to capture the hot vent gases that normally escape through the flue to preheat the household air.
- Furnaces can lose heat through the walls of the furnace cabinet. Energy efficient models will have a blanket of insulation lining the cabinet to prevent heat loss.
- An induced-draft blower will ensure proper venting and keep heated gases moving through the heat exchanger at a constant rate; however, it will shut off when the burner cycles off to keep the heated air in the system.
- You can reduce the amount of heat escaping the furnace by using a smaller diameter flue pipe.
- A furnace with sealed combustion chambers will allow less heat to escape through the chimney.
The Benefits of a High-Efficiency Furnace
Yes, you will probably pay more for a high-efficiency furnace. But you will most likely recoup the cost in the long-run through lower operating costs. The American Council for an Energy-Efficient Economy issued a report detailing cost savings in relation to the AFUE rating of a home’s heating system. The report indicated if you currently have a system that is only 50 percent efficient, you could save up to $47 out of every $100 spent on heating by upgrading to a furnace with an AFUE of 95 percent.
Since many of today’s home buyers are concerned about energy efficiency, upgrading your furnace may even enhance the resale value of your home.
The Benefits of Regular Furnace Maintenance
Whether you have an older furnace or a newer high efficiency model, regular maintenance will also affect your furnace efficiency. Remember the furnace efficiency rating assumes the furnace is operating properly.
We’re proud to be Denver’s home comfort experts. For new furnaces or maintenance of existing ones, we promise you’ll be satisfied. Contact us today for more information or to schedule an in-home evaluation. We look forward to the opportunity to serve you.