What does ‘efficiency’ really mean when it comes to your gas furnace?

As we go deeper into fall, your gas furnace will be running a lot to heat your Portland-area home. If you have a high efficiency gas furnace, you might be feeling pretty good about your monthly heating bill. However, efficiency actually means something different for every high-efficiency gas furnace.

In short, efficiency refers to the percentage of heat, produced by the furnace, that you actually use in your home. A higher efficiency percentage means that more of the furnace’s heat is actually being used inside of your home. When the number is lower, that means you’re losing more heat in the venting process.

Let’s break efficiency down by the numbers and types of gas furnaces.

Consider the 80% efficiency furnace for a moment. Perhaps your 80% efficiency furnace has never given you a problem. However, even if it’s working as hard as it can, you’re still losing 20% of the heat it produces. This lost heat is going out through the exhaust pipe venting that an 80% efficient furnace uses.

In fact, one way to tell if your furnace is an 80% efficiency model is by the vent piping. Most 80% efficiency gas furnaces use metal exhausting vents. Meanwhile, gas furnaces that are 90% efficient or higher vent via PVC pipes.

Here’s something else to keep in mind: even the most efficient furnace will lose some of its efficiency over time. In other words, if you’ve been relying on your 80% efficiency gas furnace for a decade or more, it is probably only operating at 75% efficiency at this point.

Most heating and cooling professionals agree that 80% efficient gas furnaces will eventually go away, as cities, states, and the federal government improve efficiency standards.

The vast majority of gas furnaces that we install are condensing furnaces, and at least 90% efficient.

Today’s most popular high efficiency gas furnaces are at least 90% efficient. More and more, a 95% efficient gas furnace is becoming the go-to for many homeowners. With a 95% gas furnace, you’re only losing 5% of the heat through your exhaust. We routinely install 90% and 95% efficiency gas furnaces, as well as 96%, 98%, and 99% efficiency furnaces.

How does a furnace achieve efficiency higher than 95%?

The way you achieve higher efficiency is through secondary heat exchangers. A secondary heat exchanger transfers heat through the air that’s being blown across the heat exchange, and circulates through the house. Furnaces that are 80% efficient do not have a secondary heat exchanger, while furnaces that are 90% efficient and higher do. As air passes, the secondary exchanger extracts 10-19% of the heat. That way, you’re only losing a small amount.

A natural gas furnace is the top choice for many Portland-area homeowners

Using a high-efficiency gas furnace remains one of the most cost-effective ways to heat just about any home throughout Multnomah, Clackamas, or Washington counties. If you’re considering upgrading or updating your furnace to a high-efficiency gas model, it’s worth your time to research rebates and other incentives that exist throughout the state of Oregon. 

As a licensed Bryant contractor, Comfort Connection can also help you explore and discover ways to save on a new high-efficient furnace, and choose the right model for your home.

Contact us today to start a conversation about high-efficiency gas furnace options. 

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