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How Is Furnace Efficiency Measured?

How To Choose the Most Efficient Furnace

Two Ostrom technicians servicing a furnace.

When choosing a new heating system for your home, one of the most important considerations is how efficient the furnace or heat pump will be. Furnace efficiency is measured by the AFUE standard.

AFUE stands for annual fuel utilization efficiency and is a measurement that calculates the percentage of the energy input that’s converted to heat (BTUs). The higher the percentage, the more efficient the furnace.

What Is the Minimum AFUE for Furnaces?

In the last couple of years, the minimum AFUE required for most furnaces is 80%. When shopping for a new furnace, the ENERGY STAR® rating label will help you know how efficient the unit will be and how much you can expect to pay to operate it during a typical year.

What Is Considered a High-Efficiency Furnace?

High-efficiency furnaces operate at 90% to 98.5% efficiency by using two heat exchangers in a sealed combustion chamber. A condensing unit removes moisture from exhaust gases before sending the gas through the second exchanger for increased efficiency.

If you have an older furnace, it may not be rated. The government only requires manufacturers of newer furnaces to show efficiency ratings.

If your furnace has a continuous pilot light that requires you to light it when it goes out, it’s a safe bet that it’s a low-efficiency furnace that may not even have a fan. This type of furnace will typically operate at 56% to 70% efficiency.

Have questions about choosing an energy-efficient furnace for your home? We can help contact Ostrom Electrical Plumbing Heating & Air Conditioning today.

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