Hardwoods – the well named rock elm, hickory and some oak stack up as great fuels for winter warmth because they throw off the most heat while burning.
That is because they are the most dense in mass and heavy in weight.
By the same token, they are not suitable in the moderate spring and fall seasons when such intense heat might be uncomfortable.
Heat Values of Common Hardwoods (million) BTU
Rock Elm 32.0
Shagbark Hickory 30.6
White Oak 30.6
Bitternut Hickory 29.2
Sugar Maple 29.0
Red Oak 27.3
Yellow Birch 26.2