How A Sealed Furnace Benefits Your Home

Energy efficiency is a big deal for many new homes and plenty of older homes, as well. That means the average home is built with fewer opportunities for indoor air to leak out (and outdoor air to leak in, for that matter). This tighter envelop makes it easier to heat your home efficiently, but it can also pose some dangerous issues if you're using a conventional furnace that's left open to your home. A sealed furnace is usually the safer and better choice for today's tightly sealed and insulated homes.

Atmospheric Furnaces and Tight Homes: Not an Ideal Combination

A typical gas or oil-fired furnace relies on two things for its combustion process -- fuel and air. If you have an atmospheric furnace, the latter comes from the air immediately around your furnace and possibly other parts of your home, as well. As your furnace mixes and burns the fuel and air in its combustion process, the resulting exhaust gases are forced upwards through the flue thanks to negative air pressure created by the heat of the exhaust. The atmospheric furnace design was popular with furnace manufacturers due to its relative simplicity and low cost, but it also required a balancing act when it came to your home's air pressure.

In a tightly sealed home, an atmospheric furnace can draw enough air to cause surrounding air pressures to drop. If that happens, higher air pressures at the flue's outlet could cause exhaust gases to flood back into the room and create a dangerous carbon monoxide poisoning risk. Such backdrafts can also prevent the furnace from burning its fuel properly, which could result in incomplete combustion that raises carbon monoxide levels further while lowering the furnace's overall efficiency.

Atmospheric furnaces aren't all that energy efficient, either. According to the U.S. Department of Energy, annual fuel utilization efficiency (AFUE) ratings for a typical atmospheric furnace can be as low as 56 percent for older furnaces and as high as 83 percent for a mid-efficiency furnace with electronic ignition.

Sealed Furnaces Can Help Eliminate Backdrafts

While an atmospheric furnace is content to use your home's indoor air, a sealed furnace does things a bit differently. For starters, the combustion chamber is completely sealed off from your home. Instead of taking in air surrounding the furnace, a sealed furnace draws air from outside the home through an intake pipe. Meanwhile, exhaust gases are directed away from the furnace and your home through a separate exhaust pipe.

Since sealed furnaces don't have to draw indoor air, there's no risk of an air pressure imbalance causing the exhaust gases to re-enter your home. By eliminating backdrafts, a sealed furnace will also significantly reduce the risk of carbon monoxide poisoning in your home. A sealed furnace is also ideal for improving your home's indoor air quality, especially if you're living in a modern home that's tightly sealed and insulated against heat and energy loss.

Sealed Furnaces Can Also Save Money

Sealed furnaces also have their benefits when it comes to saving money. A typical sealed furnace uses a secondary heat exchanger to draw additional heat from exhaust gases before they're expelled from the furnace. The resulting exhaust byproduct is usually condensed into mostly water vapor. Wringing this normally-lost heat helps bump up the average sealed furnace's AFUE as high as 98.5 percent.

Thanks to the sealed combustion chamber, sealed furnaces are also less likely to draw existing warm air produced by your furnace out of other areas of your home. The reduced heat loss offered by your new sealed furnace can also help you save on your annual heating costs. Talk to your furnace contractor for more information.


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