A question we are often asked is whether you need to burn dry or split wood in your outdoor wood boiler. In this post we'll try to tackle the issue.
In the past, when asked this question, we told customers that they could burn anything in their outdoor wood boiler, green wood, dry wood, oak or pine, as big as you could lift through the door. This is still true for MF-Series units, which as of 2016, are available only for commercial use in the United States, but gasification designs(G-Series) require a bit better treatment. We recommend burning well seasoned wood, generally about 15% to 25% moisture content. Burning dry wood you get more heat, less creosote, and less ash, making it the better choice all around. Wood should be cut approximately 4 inches shorter than the fire box length and split to 6 inch chunks or less. The difference in weight between a cord of wet wood and a cord of dry wood is quite a bit, and every pound of water in chunk of wood must be evaporated when it is burnt, consuming much of the energy in the wood. This short video explains Heatmaster's recommendations for wood preparation. Heatmaster SS sends a wood moisture tester with every unit so customers can easily check their wood moisture.