The primary content of a furnace basket should be fuel, specifically designed for the type of furnace being used. The most common types of fuel include wood, coal, or pellets, depending on the furnace's specifications. It is crucial to use the correct fuel to ensure efficient and safe operation. Using inappropriate fuel can lead to inefficient combustion, increased emissions, and potential damage to the furnace.

Wood is a popular choice for furnace baskets due to its availability and renewable nature. However, it is essential to use dry, seasoned wood with a moisture content of less than 20%. This ensures optimal combustion and reduces the risk of creosote buildup, which can cause chimney fires. Coal is another option, but it requires a different type of furnace and should be used with caution due to its higher carbon content and potential for air pollution.

Pellets, also known as biomass fuel, are a convenient and clean option. They are made from compressed wood or agricultural waste and can be used in pellet-burning furnaces. Pellets have a consistent size and shape, which makes them easy to handle and burn efficiently.

Data from the U.S. Energy Information Administration (EIA) shows that wood and coal are the most commonly used fuels for residential heating. In 2020, about 45% of U.S. households used wood as their primary heating fuel, while coal accounted for 5%. Pellets, although less common, have been growing in popularity due to their environmental benefits and efficiency.

Using the correct fuel in the furnace basket not only ensures efficient heating but also contributes to environmental sustainability. For instance, using wood from sustainably managed forests can reduce the carbon footprint associated with heating. Additionally, using clean-burning fuels like pellets can significantly reduce emissions compared to traditional coal.

In conclusion, the furnace basket should primarily contain the appropriate fuel for the furnace, such as wood, coal, or pellets, depending on the furnace's specifications. Using the correct fuel is essential for efficient and safe operation, as well as for environmental sustainability.