What is the Best Wood Type to Use for Your Outdoor Wood Stove?

What is the best wood type to use for your outdoor boiler?

It has been proven that firewood is the most affordable heating fuel ever created. Burning wood inside a heating appliance can be messy, labor-intensive, and even risky. Therefore, to solve these concerns and yet take advantage of the chance to reduce heating costs by using firewood, industry experts have developed incredibly inventive methods.

The solution? An “Outdoor Wood Boiler”!

An outdoor wood boiler is a heating device that is usually located outdoors away from the building(s) for which it provides heat. The energy from burning wood is transferred into a tank of water surrounding the burn chamber in outdoor boilers. The heated water is then pushed into the building(s) through an insulated PEX pipe where it interfaces with the existing heating systems of those buildings.

But we get calls from customers who are telling that despite having plenty of wood, their outdoor wood-burning furnaces are unable to adequately heat their homes. After asking some sort of questions to analyze the issue, we then realize that the problem originated with the type of wood that they use.

In this article, we will explore the key factors to consider when choosing the best wood for your wood boiler.
Type of Wood

Greenwood vs. Seasoned Wood

Greenwood is wood that has been freshly cut down while seasoned wood is split, stored, and allowed to dry, reducing its moisture content. Seasoned wood is far more efficient and will provide your furnace with longer-lasting heat.

You can still burn greenwood if you want to. However, the amount of energy produced is reduced since much of the heat produced is utilized to evaporate the water. It also causes creosote build-up.

Freshly cut green wood contains up to 50% moisture. That means that 50% of the weight of the wood is water.

When you try to burn green wood, you must first use up your precious BTUs from your fire to boil off the water in greenwood. Those are BTUs that could have gone into your home but instead are wasted.

Read our article to know the “3 Most Important Steps” when preparing your wood.

Hard Woods vs. Soft Wood

Softwood catches fire rapidly and has more BTUs per pound than hardwoods, making them suitable for starting a fire, however, they deposit a lot of creosote and burn up quickly.
Hardwood firewood, on the other hand, has a longer burning time, but you should plan on seasoning and preparing your firewood before putting it in your wood boiler.

Top Hardwood Species for Wood Boilers

  1. Oak
  2. Maple
  3. American Beech
  4. Hickory
  5. Ash
  6. Birch

Things to Consider When Collecting Firewood

The amount of time for proper seasoning depends upon many factors, but if you have a GASIFIER outdoor wood boiler, you should have already cut, split, and stacked your wood for this upcoming winter. It will take at least 6 months for green hardwood to properly dry in order to burn properly in your GX Series or other gasification outdoor boiler. You actually should prepare your wood this summer for next Winter.

All other traditional outdoor wood boilers will sometimes operate a little better with some higher moisture-content wood. This is because they are not high-efficiency furnaces and a load of really dry wood will burn up like a pile of match sticks, and too much of that heat will exit the chimney before it has a chance to transfer through your furnace walls into your water jacket. Do NOT burn all green wood, but also don't just burn 'matchstick dry' firewood in your outdoor boiler either.

On a 32-degree day, it takes more BTUs to maintain your home's temperature at 72 degrees than it does when it's 55 degrees outdoors.

How Much Wood Is Consumed in an Outdoor Boiler?

So, how much wood should an outdoor wood stove utilize? The answer is, it depends. There are a lot of factors to keep in mind that affect the process.

Factors Affecting Wood Consumption on Your Outdoor Boiler

  • The size of your home
  • The quality of your underground PEX pipe
  • The weather
  • The insulation of your building


It is important to use the proper kind of wood for your outside wood boiler to achieve maximum efficiency and minimize environmental effects. Though hardwood is preferred for its high energy content and lower moisture levels, you need to make sure that it’s properly seasoned. When wood is properly seasoned, combustion is efficient, resulting in reliable and pure heat output.

Always remember to ask your wood boiler manufacturer and the experts for specific advice based on your boiler model and location.

Contact OutdoorBoiler.com for more information.