Introducing the Classic Edge Titanium HDX outdoor wood furnace. Classic Edge HDX models are among the most efficient outdoor wood furnaces that are EPA Step 2 Certified. High efficiency means less wood is needed to heat your entire home, domestic hot water and more. The titanium-enhanced stainless steel firebox is impervious to corrosion and designed to last a lifetime. Thousands of families rely on their Central Boiler furnace to provide warmth, safety and comfort while eliminating their high heating bill and giving them a better quality of life.