What Is An Efficient Furnace?

Posted on: 24 July 2023

Everyone wants an efficient heating system, but some do not understand the meaning of heating efficiency. Unfortunately, you might not get an efficient system if you do not understand efficiency issues. Below is an overview of furnace efficiency and the factors that determine the efficiency.

Furnace Efficiency Explained

A furnace requires energy to heat your house; the furnace converts the energy to heat. However, the furnace doesn't convert all the energy it consumes to heat. In addition, not all of the converted heat warms the house. All furnaces lose some of the energy via different sources. For example, a gas furnace loses energy in the form of:

  • The heat that escapes along with the flue gas
  • Fuel that doesn't burn completely in the combustion chamber
  • The heat that escapes the furnace before heating the air it's supposed to heat

A furnace's efficiency determines how much energy it consumes to heat the house. The more energy the furnace uses for actual heating, the more efficient the furnace is.

The Numbers

HVAC professionals assess furnace efficiency as annual fuel utilization efficiency (AFUE). AFUE presents the annual heat output of a furnace compared to its energy consumption over the same period. AFUE shows much of the energy a furnace consumes goes to waste.

HVAC professional calculates AFUE as a percentage. For example, an AFUE of 90% means that a furnace uses 90% of its energy consumption to heat the house; the rest 10% is wasted. Consider a household that uses 1,000 gallons of gas per year for heating. If the household's furnace has an AFUE of 90%, it means 900 gallons heat the house, and 100 gallons go to waste.

Factors Determining Furnace Efficiency

Multiple factors determine a furnace's efficiency. Here are a few examples:

  • Fuel type – some fuels burn more efficiently (completely) than others.
  • Ignition style – new ignition systems (such as electric igniters) are more efficient than older ones (such as pilot lights).
  • Combustion chambers – sealed combustion chambers lose less heat than others.
  • Burners – multi-stage burners that run at various speeds are more efficient than single or dual-stage burners.

Remember, these factors determine each furnace's intrinsic efficiency; the efficiency you get if the furnace operates under ideal circumstances. The furnace's use, age, and maintenance will affect its efficiency.

 Let the contractor maintain and repair your system so you can continue enjoying efficient operations. Limit DIY repairs and maintenance if you have limited HVAC understanding. 

Contact an HVAC contractor to help you install a heating system.