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More About Furnace Efficiency: Why Are New Furnaces More Efficient?

furnace-burners-against-blackLast week we went into details about gas furnace efficiencies, specifically the AFUE rating and whether it means you’ll save energy with a high-efficiency furnace or not. It’s a question that is best left to a professional to answer.

However, we want you know that we definitely encourage consumers to look into high-efficiency furnace options when they start looking around for a new installation or a replacement for an older heater. The AFUE ratings of furnaces are higher than they’ve ever been: older furnaces used to average between 56% and 70% AFUE ratings, which meant wasting between 44% and 30% of the natural gas the furnace burned. Today, furnaces range from 85% to 98.5% AFUE, and the ENERGY STAR requirement for a furnace is 90%.

But why exactly are furnaces able to perform at such energy-saving levels today? There are several reasons.

Improved Heat Exchanger Construction

You could file this under “they just got better at building them!” The heat exchanger in a gas furnace is the place where the furnace actually heats the air. Combustion gas from the burners collects in the heat exchanger, which heats up the metal walls. The hot metal transfers heat to the air from the blower. Older furnaces used heavy, thick heat exchangers, but newer ones have lighter heat exchangers that transfer more heat to the air.

Electronic Ignition Systems Replacing Standing Pilot Lights

The standing pilot light was the way that gas furnaces lit their burners for decades. Unfortunately, letting a pilot light burn through the winter also wasted energy. Pilot lights are now being replaced with electronic ignition systems that only need to turn on to light the burners. This cuts down significantly on energy consumption.

Multi-Stage Burners

The old standard for furnace burners was that they were either on or off; a furnace used full power or none at all. Multi-stage burners, such as those found in two-stage furnaces, can modulate the level at which they work. If the house doesn’t need as much heat, the furnace automatically lowers the burner to reduced capacity, consuming less energy. Most furnaces will operate at lower capacity 60% of the time.

Sealed Combustion

The combustion chambers of modern furnaces are sealed off from the house. You can’t look into the furnace and see the blue light of the burners the way you used to. This construction is called sealed combustion, and it helps lower the amount of heat the burners would lose to the air around the furnace. Instead of drawing on air in the house for combustion, these new furnaces pull the air from the outside using a PVC pipe. Along with increasing energy efficiency, sealed combustion furnaces are safer and won’t dry the air in a home.

When you want help with your new heating system installation in Burlington, VT, simply contact our office. We have NATE-certified technicians ready to give you the best help possible, and we back up our work with a one-year labor warranty on top of the manufacturer’s warranty.

Red Rock Mechanical LLC—serving Burlington and the Plattsburgh, NY area for more than 23 years.

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