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Everything You Need to Know About Furnace Efficiency

As the weather gets colder, your furnace works harder to keep your home warm. If you've noticed that your gas bill is higher than last year's or that your house isn't quite as warm, your furnace may not be running as efficiently as it once did. To get to the root of the problem, you should understand how furnace efficiency is measured and what factors can affect it.

What Does My Furnace’s AFUE Rating Mean?

To understand how efficient your furnace is, you’ll need to understand its AFUE rating. AFUE, or annual fuel utilization efficiency, is the percentage of heat your furnace produces per dollar of fuel it consumes. Furnaces with a higher AFUE rating are better at converting fuel to energy. In other words: the higher the rating, the more efficient the furnace.

For example, a furnace with an AFUE of 90% will convert 90% of its fuel into heat, and the remaining 10% escapes during the heating process. A furnace with an AFUE of 75% will only use 75% of its fuel to produce warmth, and the other 25% is lost throughout the heating process.

The minimum standard for new furnaces is an AFUE of 78%. The U.S. Department of Energy considers furnaces with an AFUE of 90 to 98.5% to be "high-efficiency." In short, the better the AFUE rating, the more heat your home gets per dollar you spend on fuel.

What Can Affect My Furnace’s Efficiency?

While AFUE measures your furnace's efficiency in optimal conditions, several factors can impair even a high-efficiency furnace's ability to convert fuel into heat.

  • A clogged air filter: When there’s too much dust coating the filter, your furnace struggles to get enough air from the intake vent to then push through the heating system. A dirty filter can also worsen the air quality in your home.

  • Equipment age: The average life expectancy of a furnace is 15 to 20 years. As your furnace gets older, it may not heat your home as effectively as it did when it was new.

  • Lack of maintenance: Many homeowners are surprised to see just how much dirt makes it into their heating system when a technician shows them. Dirt can accumulate on just about any of the furnace’s components and reduce the equipment’s heating ability.

If you own a well-maintained furnace that's the correct capacity for your home, the furnace still might be under unnecessary strain due to poor insulation and air leaks in windows, doors, and ductwork. Although this isn't a problem with the furnace itself, the equipment has to work harder to heat your home.

How Can I Improve My Furnace's Efficiency?

If your furnace isn't working as well as it used to, the first thing you should do is replace the air filter. As mentioned above, a clogged filter makes it difficult for your furnace to do its job.

Improving the air circulation in your home can help, too. Make sure that no furniture or carpeting is covering up any vents. If you have ceiling fans, turn them on (rotating clockwise) to push down hot air that has risen to the ceiling. It also helps to clear a few feet of space around your furnace to let the air circulate freely.

The most effective way to keep your furnace working efficiently is to get annual professional maintenance. Not only does regular maintenance help your furnace run like new, but it also helps the equipment last longer. Plus, it’s the best way to prevent costly repairs down the road.

If you have any questions about furnace repair, maintenance, or installation, contact our Ann Arbor HVAC experts at Iceberg Heating & Cooling: (734) 375-1119.

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