Heating equipment is a significant investment for homeowners, so you should choose your new unit carefully. Here are some important factors to consider when buying a new furnace.
Annual Fuel Utilization Energy Efficiency (AFUE)
A furnace’s efficiency is measured by its annual fuel utilization efficiency (AFUE), a percentage which represents a unit’s annual heat output compared to the energy consumed. For example, an AFUE of 90% means that 90% of the energy put into the furnace becomes heat for the home. The other 10% is lost through the chimney and elsewhere. Finding out a new furnace’s AFUE is not difficult. The Federal Trade Commission requires new furnaces to display their AFUE so you can more easily compare various models.
You can identify and compare a system’s efficiency by not only its AFUE but also by its equipment features. Old, low-efficiency heating systems only have AFUEs between 56% – 70%. They also have a heavy heat exchanger, continuous pilot light, and a natural draft that creates a flow of combustion gases. Mid-efficiency heating systems possess AFUEs between 80% – 83%, electronic ignition (no pilot light), and an exhaust fan that controls the flow of combustion air and combustion gases more precisely. High-efficiency heating systems possess AFUEs between 90% – 98.5%, sealed combustion, and they condense flue gases in a second heat exchanger (for extra efficiency).
Single-Stage, Two-Stage, and Modulating Furnaces
- Single-Stage Furnaces: A single-stage furnace (also known as a single speed furnace) uses one setting—high—to heat your home. Single-stage furnaces operate at maximum capacity, all the time, using 100% of their resources to heat a home, regardless of the temperature outdoors or in certain areas of your home. This type of furnace is often the least energy efficient and can lead to increased utility bills.
- Two-Stage Furnaces: Two-stage furnaces (also known as two-speed furnaces) operate with two settings. The first stage supplies heat to your home by using approximately 65% of the furnace’s total capacity. When outside temperatures drop and the first stage is unable to meet your home’s heating needs, the second stage kicks in. Two-stage furnaces are quieter than single-stage furnaces because they don’t operate at 100% capacity every time they run, which also creates less carbon dioxide emissions for the environment.
- Modulating Furnaces: A modulating furnace (also known as a variable speed furnace) is the most energy efficient and most accurately heating furnace. A modulating furnace can control the temperature in your home to within a half-degree of your desired temperature, compared to a 4 to 6 degree variant in single-stage and two-stage furnaces. In a modulating furnace, the unit’s fan is capable of circulating air throughout your HVAC system at all times, resulting in improved airflow, increased temperature and humidity control, and an overall more comfortable environment. When initially turned on, a modulating furnace will begin heating using 100% of its fuel. After warming up, the furnace will decrease the amount of fuel used and increase its fan intensity to maximize energy efficiency and improve air circulation. This can result in less energy consumption and lower utility bills every month.
If you are in the market for a new furnace, call the professionals at Cochran Cooling & Heating today. We can help you make the right choice for your home.