How to Estimate the Efficiency of a Furnace

Efficiency in a home furnace translates into energy savings.

When you are purchasing a new furnace for your home, one of the most important things you need to consider is the overall efficiency of the furnace. You can use several key pieces of information to estimate and compare the efficiencies of the various home furnaces you're considering. Once you've compared all of these factors, you should be able to choose the furnace with the highest estimated efficiency level for your home.

Instructions

1. Look for furnace models that have a second heat exchanger as part of their design. Generally, this added heat exchanger will boost the efficiency of the furnace.

2. Find out if the furnaces you're considering have sealed combustion. Sealed combustion units draw air in from outside for combustion, rather than using and then venting the indoor air you've paid to heat. Sealed combustion is a frequent feature of high-efficiency heating systems.

3. Get a furnace with a programmable thermostat. While this doesn't make the furnace itself more efficient, you can use the programmable thermostat to control the output of the furnace more effectively, which boosts the efficiency of the heating system as a whole.

4. Compare the annual fuel utilization efficiency (AFUE) ratings for the furnaces you're considering. This rating takes the guesswork out of your efficiency estimates and tells you how efficient a furnace is. The rating must be a minimum of 78 percent. The closer to 100 percent the rating is, the more efficient the furnace is.

Tips & Warnings

• You can help make efficient use of your furnace, no matter which model you choose, with some simple attention to how you utilize it. Turn down the thermostat at night. Install more energy-efficient windows in your home, and seek out and seal any leaks in the ducts of your heating system. Weatherize your home, and make sure curtains are drawn at night to help retain heat. Utilize solar heat gain as much as possible during the day by allowing sunlight into the home. Open windows when the temperature outside is higher than the thermostat setting, and close them to hold the free heat you've gained once the outside air has reached its peak temperature for the day.

References

• U.S. Department of Energy: Furnaces and Boilers
• Consumer Reports.org: Gas furnaces -- Efficiency matters