outdoor wood furnace

How Does an Outdoor Wood Furnace Work?

In Tips by Jamie

If you have ever looked at your home heating bill and wished there was a way around it or you are looking to move away from dependence on the fossil fuel industry, outdoor wood furnaces are one home-heating option to consider.

Outdoor wood furnaces work by converting wood into energy through a process called gasification to produce hot air. The hot air then circulates in the firebox, blowing hot air into your home through ducts. To connect to your home’s ducts and minimize hot air loss, your outdoor wood furnace should be located no more than 40 feet away.

These furnaces can provide cost and eco-friendly solutions to your home heating needs, and with proper care and maintenance, you will reap the benefits for years to come.

What is an Outdoor Wood Furnace?

An outdoor furnace is a home heating mechanism that many find to be more cost-effective and energy-efficient than other home heating methods. It does not require dependence on oil and gas companies as it simply requires firewood to function.

How Does an Outdoor Wood Furnace Work?

An outdoor wood furnace works through a process called gasification in which, wood is converted into energy. Heat breaks down the wood into a compound called syngas (composed of hydrogen and carbon) that is burned to heat air. The heated air is then sent into the areas of your home needing heat through ducts.

How Much Does It Cost to Install an Outdoor Wood Furnace?

In the United States, most people pay an average of $8000-$15000 to install an outdoor wood furnace. The cost of installing an outdoor wood furnace is offset by the long-term savings of running it compared to conventional gas heating. Wood heating costs a fraction (usually less than 10%) of what electric and gas heating costs.

Are Outdoor Wood Furnaces Efficient?

Outdoor wood furnaces are both cost-efficient and eco-friendly compared to conventional electric and gas heating methods. Wood heating will cost you less than 10% of what electric heating costs. Many people find the freedom from the fossil fuel heating industry alluring.

For this reason, outdoor wood furnaces are also viewed as being eco-friendlier, requiring less wood to heat your home than gas required in conventional heating mechanisms. Whereas fossil fuels are a non-renewable energy source with high emissions, acquiring wood ethically in a way that it regenerates is possible. Wood furnaces also release minimal emissions into the atmosphere.

Outdoor wood furnaces are built to be durable to resist various weather conditions and consistently handle high heat. When well-maintained, they should last a lifetime.

How Long Will an Outdoor Wood Furnace Burn for?

Many new outdoor wood furnaces only need to be fed wood once or twice a day. In the summertime, you may only need to feed your furnace wood once every 3-4 days to heat water in your home. In the depths of winter, you will likely need to feed your furnace twice a day. In temperate climates, you may need to feed your furnace once a day during spring and autumn.

Outdoor Wood Boiler vs. Outdoor Wood Furnace (Is there a difference?)

You will sometimes find outdoor wood boilers and outdoor wood furnaces used interchangeably. When speaking about outdoor forced air furnaces, there are differences from outdoor wood boilers.

Outdoor forced air furnaces work by circulating hot air around the firebox instead of water, so no exchange pump is needed which then blows hot air into your home.

Forced air furnaces need to be located close to your home and are only able to heat one building whereas, outdoor wood boilers can heat multiple buildings and can be located slightly farther away from the building.

Outdoor wood boilers produce less smoke because they only turn on to heat the water to a certain temperature every few hours then turn off once the water has reached that temperature. A forced air furnace will heat at regular intervals (usually 20 minutes) causing slightly more smoke because of the fire being built each time.

How to Hook up Outdoor Wood Furnace to Ductwork?

An outdoor forced air wood furnace requires two ducts to function; one for supply and one for return. The ductwork can either be buried and insulated under the ground or exposed, running through a wall or window into the house.

Though it can be more expensive than exposed ducts, buried ducts tend to be more visually appealing, feeding into your basement’s duct system. Underground ducts should be buried below the ground frost line to insulate them against harsh cold temperatures.

You may need adapters or flanges to connect the ducts to your existing square or rectangular ductwork. Ideally, the furnace should be located within 40 feet of your home’s existing ductwork to minimize heat loss and airflow loss.

Can You Build a DIY Outdoor Wood Furnace?

It is possible to build an outdoor wood furnace, especially if the area that needs to be heated is small and is located in an area where weather conditions are mild year-round. If you live in a temperate climate, have a large building to heat evenly, or want your furnace to last a lifetime, it is best to have it professionally installed. The initial investment can save you time, money, and effort in the long run.

If you wish to build your own outdoor wood furnace videos like this show you how to do so.

Where Do the Ashes from an Outdoor Wood Furnace Go?

Many outdoor furnaces will not have an ash pan, meaning that part of the regular maintenance entails cleaning ashes out of the firebox while the fire is burning or when it has completely cooled off.

Final Thoughts

Whether you are looking to save money on your home energy expenses or gain independence from the fossil fuel industry, outdoor wood furnaces provide a viable solution to heating your home. Not only is wood a renewable resource, but it also produces far fewer emissions than electric and gas-based heating mechanisms. Outdoor wood furnaces give you ultimate control over your home’s heating.