What Is an Outdoor Forced-Air Wood Furnace and Is It Right for Your Home?

When you think about where to install a new furnace, your first thought is probably your basement or utility closet. But in some cases, you might be able to add a furnace to the outside—rather than the inside—of your house. Known as outdoor forced-air wood furnaces, these devices could make sense, depending on where you live and the resources available in your area. Here’s how to figure out if this type of furnace is right for you.

What Is an Outdoor Forced-Air Wood Furnace?

Like its indoor counterpart, a forced-air outdoor wood furnace is a heating device that uses burning wood to heat your house. These types of furnaces can heat a single room or your entire house, depending on the model that you pick and the size of your home.

How Do Outdoor Wood Furnaces Work?

As the name would suggest, these devices sit outside of your property. Wood burns in the firebox (which also serves as the heat exchanger) and produces hot air that rises into the metal plenum above. From there, an electric fan pushes the heat into your home through a duct system.

How Much Does an Outdoor Forced-Air Wood Furnace Cost?

Outdoor wood furnace prices vary depending on a few factors, including the brand and size of the unit. Smaller outdoor forced-air wood furnaces are effective for more compact spaces (like garages, barns, or sheds), but if you size up, you could generate enough heat to warm up your basement or whole home. If you have a larger home, you’ll need a larger furnace with more BTUs. BTUs, which stands for British Thermal Unit, are a measure of how much energy your furnace uses to warm your home.

In general, you can expect to pay between $6,000 and $12,000 before installation. You can save a bit of money if you DIY an outdoor wood forced-air furnace, but be aware that it’s a potentially dangerous job that involves heavy equipment and electrical and ducting work.

Even if you are typically a hands-on person, a better (and safer) option is to hire a furnace installer near you. Not only can they manage the entire installation process, but they can also assess your space and help you decide which type of outdoor wood furnace is best for your home.

Common Uses for Forced-Air Wood Furnaces

So, why would you consider installing a forced-air wood furnace over other types of heating systems? For one, if you live in a rural area where you can’t easily access natural gas or electricity, then an outdoor wood furnace might be a good heating option for your home. Similarly, if you have ample access to firewood, using a forced-air wood furnace can be an affordable way to heat your home.

Pros and Cons of Outdoor Wood Furnaces

Not sure if an outdoor forced-air wood furnace is right for you? Consider these pros and cons.

Pros

• Unlike traditional indoor furnaces, outdoor versions don’t take up room in your home. If you don’t have enough space for a basement or attic furnace, installing a furnace outside might be wise.

• Affordability is another advantage of outdoor wood furnaces. Wood is more affordable than many other fuel types—especially if you already have a lot of it on your property.

• Outdoor furnaces can be safer than indoor ones. By placing your furnace outside rather than inside, you may be able to reduce your risk of a house fire.

Cons

• Tending to a wood furnace can be tedious work. Not only do you have to have a steady supply of timber (and space to store it), but you also need to load your furnace with wood every day. 

• There’s a good amount of clean-up needed to run a wood furnace. When moist wood burns, it creates a dangerous and flammable substance called creosote. It needs to be removed to keep your furnace operating safely. You’ll also have to dispose of the ashes regularly.

• While outdoor furnaces can save you money over time, they can be costly to purchase and install.

Outdoor Wood Forced-Air Furnace vs. Outdoor Wood Boiler

In many ways, outdoor wood furnaces are similar to outdoor wood boilers.

At a basic level, both are wood-burning devices that sit outside and warm your home. An average outdoor wood-fueled boiler costs between $7,000 and 16,000. An average outdoor forced-air wood furnace costs slightly less at $6,000 to $12,000 (but its life span is also lower than that of a wood boiler).

With that said, there are some big differences between the two heating devices. Most importantly, furnaces rely on air to circulate heat through your home, while boilers use water. And while a furnace transfers heat into your home through ductwork, a boiler heats up a “water jacket” around the firebox, then pumps warmed-up water through a set of pipes and into your house.

It’s also important to note that there may be additional expenses associated with both outdoor furnaces and outdoor boilers. For instance, with a furnace, you may have to cover air duct replacement costs. For boilers, you’ll have to factor in piping-related costs. But after installation, both outdoor wood furnaces and boilers can be less expensive to run than other heating systems—as long as you have a steady supply of wood.