Beware Of The Oversized Furnace

Posted on: 31 August 2015

When it comes to buying and installing a new furnace, one of the biggest mistakes you can make is thinking that bigger means better. It's tempting to buy a furnace that's powerful enough to heat your home and then some, but an oversized furnace comes with a lot of drawbacks that outweigh the supposed benefits.

The following provides an in-depth explanation of the problems an oversized furnace can cause. You'll also learn exactly why the right size is the best size for your furnace.

Those Short Cycling Blues

An oversized furnace may be more than capable of heating your home quickly, but it comes at the expense of longevity. The average furnace is designed to gradually raise indoor temperatures to desired levels, which also gradually adds heat and stress to the various components within the furnace. An oversized furnace, on the other hand, raises temperatures in a very short amount of time before shutting down just as quickly as it came on.

This is commonly referred to as "short cycling," where the furnace turns on and off constantly in order to maintain your desired temperature. In many cases, the oversized furnace puts out so much heat that the system shuts itself down to prevent overheating. Not only does short cycling subject moving parts such as your blower fan to increase wear and tear, but it also subjects metal components such as your heat exchanger to the extra stress that overheating brings.

Think of it in terms of "city miles" vs. "highway miles."  Just as stop-and-go traffic adds more wear and tear on your car, an oversized furnace's constant starting and stopping adds excessive wear, bringing it one step closer to premature failure.

A Wide Gulf in High and Low Temperatures

A properly sized furnace is able to keep the highest and lowest temperatures in your heated spaces just a few degrees apart. In fact, those temperature variations are so minute that you wouldn't even notice them on a normal day.

An oversized furnace is more likely to cause a wide gulf in your highest and lowest temperatures. Without the gradual heating effect that a well-balanced furnace offers, overly hot air winds up being dumped into colder spaces, allowing wider temperature variations than you'd normally be comfortable with.

Oversizing Isn't Economical

Last but not least, an oversized furnace could prove to be a bigger hit to your wallet than you realize. For starters, the short cycling problems that often come with oversized furnaces can cut your furnace's life expectancy.

In other words, your system will have a much shorter life than the projected 15 to 20-year lifespan of typical furnaces. Considering how it can cost as much as $14,000 to purchase and install a furnace, according to Angie's List, it doesn't make sense to buy a furnace that wears out in just a few years' time simply because it's too big for your home to properly handle.

Oversized furnaces also tend to consume more energy than a properly-sized furnace, especially during the all-too-brief start and stop cycles. A short run time also translates into less time for your furnace to efficiently burn its fuel, resulting in an inefficient burn that not only wastes fuel, but also creates more pollution. In contrast, a furnace that's the right size for your home runs long enough to thoroughly convert all of its fuel to the heat your home needs.

If you live in a cold climate or are currently having trouble keeping your home warm, then turning to an oversized furnace isn't the way to go. Instead, there are plenty of improvements you can make in and around your home to reduce energy losses and cut down on outsized heating demands. You should focus on these improvements first before figuring out what size furnace your home really needs.

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