Jim:
A few comments about the article discussing soft maple as a “softwood” firewood. Technically, Soft Maple is not [classified as] a softwood, it is a hardwood. That being said, yes it is a fine firewood – sometimes better that hard maple because it dries faster. I’ve heated my farm house and barn 100% with wood for many years. I also own several 100 acre-plus stands for “hard” and “soft” maples.
A softwood is a needle-bearing conifer and a hardwood is a broadleaf deciduous tree. Some softwood trees have harder and stronger wood then many hardwood trees. Yellow Pine is a prime example of a very strong softwood. Basswood and Poplar are examples of very soft hardwoods.
When it comes to wood burning – all wood has the same basic heat energy per pound. However, woods vary in density and natural water content. Denser woods also take longer to dry which can be a factor in burning wood that has not had a lot of time to lose that moisture.
Soft maple weighs less by volume as hard maple, but dries faster and splits easier. Some hard woods, like Ash, have very low moisture content before drying. Hard maple, once dried properly has more heat energy per volume and will hold a fire longer in a woodstove or furnace with finite storage space for wood.
The main danger with burning true “softwoods” is the resin most carry that plugs chimneys. Most “hardwoods” don’t have the resins. Another potential danger with softwoods is – when dry they can burn very hot. We’ve used softwoods for years for heating up a fire quick when boiling maple sap to make syrup. When using a woodstove inside a house – that is normally
fired with hardwoods – a bunch of dry softwood thrown in can make it flare up fast – and ignite a chimney wall if coated with creosote.
One more comment about the maples. The generic names e.g. “soft maple” , “swamp maple”, etc. can mean different things in different places. In my area of New York, “soft maple” connotes Red Maple, and “swamp maple” is usually a reference to Silver Maple. Hard Maple usually means just the sugar maple, but is also applied to Black Maple. They all make good firewood – and – for making maple syrup – they all work to some degree. Red maple has less sugar content and therefore takes more boiling, making the best sugar producers Sugar and Black Maple.
For reference:
A dry cord of Basswood weighs 1,980 lbs. with 13,800 BTUs per cord. Hardwood
A dry cord of Soft Maple weighs 2,752 lbs. with 19,000 BTUs per cord. Hardwood
A dry cord of Soft Maple weighs 3,680 lbs. with 25,500 BTUs per cord Hardwood
A dry cord of White Pine weighs 2,250 lbs. with 15,600 BTUs per cord Softwood
– John in Central New York